Model Engine Maker

Engines => Your Own Design => Topic started by: gary.a.ayres on April 27, 2020, 12:11:04 AM

Title: A Simple Uniflow Engine
Post by: gary.a.ayres on April 27, 2020, 12:11:04 AM
Hello All.

It has been a while, what with everything that is going on.

Hope you are all ok...

Finally and at last, I have made a start on my second engine. A slightly unusual one, this.

First of all, the 'simple' in the title of the thread refers to the simplicity of the concept of the engine. It does not mean that I think I'll find this build simple.

The design upon which I am basing the working heart of the engine is by Stan Bray. It's 'Clarence - a clapper valve engine'' from his book on building simple model steam engines:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859112.jpg)

I don't like the sound of 'clapper valve', so I'm describing my version as a 'uniflow', which I believe it is, albeit a simple example of the type. I am taking the basic working concepts and the relative dimensions of the working parts from the book. There, however, the similarity will end - mine will have a very different look, and it will be at least three times the size of the original, which has only a 10 mm bore.

Essentially this engine will be scratch built. I have an overall idea in my mind but I'll let it unfold as the thread progresses rather than set it all out here, particularly as the plan will most likely change as I go along.

I decided to start with the flywheel - or I should say flywheels. I have had these two brass discs in my parts box for some time. They are about 11.5 cm in diameter. Originally I had thought of somehow joining them to make one chunky flywheel, but I have now decided that the engine will have twin flywheels. This, along with my idea for a frame, will have implications for some of the engineering further down the line. For the crankshaft, the bigger of the two pieces of precision ground mild steel is a bit heavier than I would have chosen, but I have it in my shop and I fancy pursuing a 'use what you have' aesthetic as far as possible with this build:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859113.jpg)

The flywheels will be composite in nature, each having a central boss  made from a separate piece of brass. They will also have a pattern of holes so I had to drill out and bore the centres so that they will fit the small four-jaw chuck which is mounted on my rotary table:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859114.jpg)

So, a small start has been made.

This will be a fairly chunky engine and it will need a fairly powerful boiler to run it. More of that later...


Title: Re: A Simple Uniflow Engine
Post by: MJM460 on April 27, 2020, 01:19:49 PM
Hi Gary, good to see you building another engine.  I am looking forward to seeing what you will do to put your mark on this one.

The design seems to have much in common with the principles used in a high speed hydroplane which was written up in the magazine.  However that was was a very highly developed performance monster. Yours looks much more reasonable, but who knows where it will lead.

K.N Harris mention the uni flow principle in his book.  You might be interested to know that that is the one that really got me interested in applying thermodynamics (which was central to my working life) to understanding in some detail how this helped understanding our models, and ultimately lead to my Talking Thermodynamics thread.

So not really sitting back, as I seem to be busier than ever these days, but looking forward to following along with your new build.

By the way, how is your flash steam plant going? 

MJM460
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on April 27, 2020, 10:49:46 PM
Hi MJM, and thanks.

My hunch  is that if I make a reasonable job of this it will be a fast runner. I have the K.N. Harris book, and yes, the uniflow engines he describes seem to be of more complex designs.

I haven't progressed the flash steam generator for quite some time as I got 'diverted' into building a brake drum forge. I always considered the flash generator to be something of a side project anyway. That said, I have a sense that something of the sort could be well suited to this engine though I have a feeling I'd need a bigger coil, which would be easy enough to do.

However, I also have other plans when it comes to boilers. Not going to say any more about that at the moment as I don't want to jinx it!   ;)

Hope you are doing ok with the challenges of the pandemic. Are you still in lockdown in Australia?

Cheers,

Gary
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on April 28, 2020, 08:19:19 AM
Hi Gary, the engine you are making is very similar in principle to that high speed hydroplane, Pisces, that I mentioned, though yours will be a more appropriately gentle one to tame.  The hydroplane had the principle refined, and the manufacture developed way beyond anything I could imagine doing.

The K.N. Harris design was closer to yours in performance, but added the ďuni flowĒ exhaust ports to a more conventional engine, to get more power output.

Yours will be quite economical on steam as the inlet port will only be open briefly, thus allowing for plenty of work to be developed through expansion.  It will be happier running faster, and the overall performance will be interesting to look forward to.  Most simple engines, the inlet valve is open for longer, so they do admit more steam, then simple exhaust it to atmosphere rather than achieving so much expansion.  In the end it is all about valve port timing and there is a big variation between different designs.

With that design, the inlet port opens before dead centre, so this limits how long it can remain open after dead centre without becoming too difficult to start.  You will need to flick the flywheel, to start it, but t should run well.

I assume you will make provision to collect the exhaust steam, and not just have the port to atmosphere as per Stanís book.

Looking forward to following your boiler exploits.

Still in lock down here.  Work is acceptable here for those who canít work from home, but people in our age range are advised to stay home apart from a daily walk, which we are making the most of.  We both have hobbies that we are enjoying being able to spend more time on.  I think my wife misses company much more than I, but we both miss the social aspects of family and friends, but managing well and keeping happy.  Technology is a big help but does not entirely replace human contact, and never will.  The different approaches taken by different countries and even different states are interesting and will provide a quite good data set for the next time.

Time in the workshop is filling in the gaps left by other activities that have to be on hold, so busier than ever.  But no point making face masks at this stage as our medical authorities are not recommending them for general use.  Obviously the jury is still out on that one too, and those who analyse this stuff later will eventually work out which way we should all go.  Or will it depend on which combination of other measures are in place?

So going well here.  I hope you are also managing ok in this world that is so different from what it was less than two months ago.

MJM460
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on April 29, 2020, 10:09:50 AM
MJM - I will look for some information on the Pisces engine as I may be able gain some ideas from it.

Thanks for your explanation on anticipated performance - it's encouraging!

On the exhaust ports - yes, my plan is to collect the exhaust steam and route it to wherever. Stan Bray advises that if his design is scaled up, extra ports should be drilled rather than enlarging the single one in his version, so that's what I'll do. My thought is to make a manifold to gather the exhaust from the ports and direct it into a single pipe. Could look pretty cool too if I make a decent job of it. That feels aeons away at this point though!

The lockdown where I am has been partly eased, i.e. tradesmen who work outdoors are now back at work provided they socially distance. Otherwuse it's still the same - one walk a day, and so on. I live on an island which has managed the situation pretty well and the curve here has been pretty much flattened. They are doing much better here than they are in the UK mainland (where my daughter works as a nurse...), and I think they will ease the lockdown carefully, measuring as they go.

I'm lucky in terms of the work side of things. As a psychotherapist in independent practice my business took a bit of an initial hit, but it has picked up again in virtual form so I'm actually quite busy. My partner is a teacher and she is working from home, setting work for her students online. Not everyone is so fortunate though.

Taking a day off today to spend some time in the shop though!

Great that you are able to do the same. What are you working on?

 :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on April 30, 2020, 12:09:32 AM
A bit of progress today in the form of drilling holes in the two flywheels and turning one of the bosses.

The flywheel blanks are just brass discs (albeit quite thick ones) so they need to be fitted with a boss each so that they can be secured to the shaft. I only had a small piece of brass bar in my box so I didn't have the luxury of extra length to hold with the chuck. The solution was to use a 'superglue arbour', which was an idea that I first came across on Clickspring's youtube channel. This was the first time I have tried it and it worked really well. I cut the piece of bar into two with a parting tool and hacksaw to make the blanks for the bosses, cleaned them up and faced them and then drilled and reamed them to make a sliding fit on the shaft. I then found a piece of spare round bar in the scrap box which was slightly oversized for the hole so I turned it down to size and then fixed one of the boss blanks to it with superglue. This made easy work of what what would have been a problematic turning operation:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859632.jpg)

Once the job was done, a bit of heat from a small blowlamp destroyed the superglue, allowing the workpiece to be removed from the arbour. Prior to this I had drilled a circle of five holes in each of the flywheel blanks. These were marked out on the rotary table with dividing plate and finished on the drill press. I thought I'd try a five hole pattern as it perhaps has a more dynamic feel to it than six does. I may enlarge these holes a bit later on - it depends how it looks when the engine starts to take shape. These will be very minimal flywheels - no recess, etc. The interest will lie in the fact that there will be two of them. Here they are at the end of today along with the boss that I made:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859633.jpg)

It got quite late so I left the second boss set up with superglue arbour no. 2, ready for turning tomorrow evening. Here is the state of play so far, with the boss trial-fitted to one of the flywheels and mounted on the shaft:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859634.jpg)

The bosses will be cross-drilled and threaded for grub screws then loctited into the flywheels.

gary





Title: Re: A Simple Uniflow Engine
Post by: MJM460 on April 30, 2020, 01:40:36 AM
Hi Gary, great progress on those flywheels, and it sounds like you have the exhaust arrangements sorted.

The different approaches to lockdown are interesting.  Our outdoor workers have continued through, though there is some grumbling on large construction sites about people not modifying procedures to institute social distancing.  Yet we have not just flattened the curve, but got it right down.  New Zealand had a more severe lockdown, and had a similar result.  I believe Italy and Spain might have much more severe lockdowns and still struggling.  It is becoming clear that ďgo hard, go earlyĒ is the critical component of the strategy, to get it under control before it is established in the community.   Along with lots of testing.  Some countries seem to have low totals, but are not testing anyone, some only count hospital cases, so it is really hard to compare different results.

But one thing that is very clear, the community and the media are both very black and white, with very little understanding of uncertainty and probability, and some understanding of both is critical in this sort of situation.

Glad you and your family are ok, being on an island with early lockdown is a huge advantage.

I am busier than ever with the combination of adapting to new ways of doing everything, which just shows how much energy our brain uses and why we quickly learn to do things on automatic.

Working on two projects, one ready for some tidying up of my notes (and coming soon to a forum near you, and the other just starting, along with iPad brackets for the camera tripod for zoom meetings and similar new requirements.

Keep sheltering keep happy and keep busy,

MJM460

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on April 30, 2020, 01:04:33 PM
Thanks for the encouragement, MJM.

Yes, strict and early lockdown seems to be the winning formula. They were a little bit slow on lockdown on this island but not so slow that they couldn't get on top of it. The mainland UK, on the other hand, have been outrageously slow, and the consequences speak for themselves.

Agreed - coming off auto-pilot is tricky and time-consuming. It would be nice to think that it won't be long before we have to do it again in the reverse direction.

Good to know that you are working on projects. Any chance you could give me a heads up when you post the forum thread?
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 01, 2020, 01:08:16 AM
This evening's efforts:
 
I made the second flywheel boss, and drilled and tapped (M6) the holes for the grub screws that will secure the flywheels to the shaft:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859744.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859743.jpg)

The bosses are not a tight fit in the main parts of the flywheels, so I used a generous amount of Loctite 638 to fix them in place:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859742.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/859741.jpg)

If the rotational force of the flywheels appears likely to weaken the Loctite when in use and shear the bosses from the wheels, I'll have the option of putting a circle of small screws through the flange of each pulley into the wheels to secure them. I suspect that this won't be necessary though.
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on May 01, 2020, 01:53:57 AM
Hi Gary, good progress on those flywheels.

Your engine, by the nature of its valve operation, will tend to have a quite impulsive torque pattern rather than the smoother sine wave of a more conventional valve operation.  That will tend to stress the shear strength of your loctite connection.

And somewhat counter-intuitively, that loctite connection is near the section of the flywheel with the highest shear stress to transmit that torque.

A simple option would be to drill through the flange and wheel as you have suggested, but just insert good fitting pins, just loose enough to leave some room for the loctite, and loctite them in and file or machine flush when the loctite is set.

These pins will transfer the torque in shear, so you will be using the shear strength of the metal pins instead of the shear strength of the loctite, and the loctite only has to stop things falling off.  Easier to do than screws and tapping threads.

I know many people seem to have good experience with using loctite as glue, so it may be enough, but hard to confirm on theory alone.  The strength requires testing, as do so many theoretical issues, and so much will depend on how well you do the loctite joints with clearance, temperature, cleanliness etc.  The pins will be a better solution, and easier to fit than screws.

No problem on the heads up, but I donít have your email address.  I believe there are forum settings that cause the forum to send you notifications, so if you check those, you will get notice in your email.  But it is not far off, so if you remember to notice any little message flags when you check in to do your posts, I will send you a pm.  I donít think you get the message flags though, unless you sign in.  Unless I find your email visible in your profile.  I need to check that again too!

Keep up the good progress.

MJM460
Title: Re: A Simple Uniflow Engine
Post by: steam guy willy on May 01, 2020, 02:18:05 AM
Hi Gary , further to MJM's post I have used Sellick pins with good results...these are sometimes called roll pins and is a sort of sprung type of pin you can get them in lots of small sizes...good work going on here :)

Willy
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 02, 2020, 01:28:39 PM
Hi Both -

Well, I'm not here to ignore good advice. I haven't used Loctite many times but on the occasions that I have I've been amazed by its performance. That may actually have led me to wrongly believe that anything can be achieved with it, even though aesthetically in an ideal world I'd probably prefer not to use glue in engines at all. Rather than wait for things to go wrong and fix them later, I'll go with what you suggest and do a proper job now.

MJM - it is actually quite intuitive to me that the shearing torque will be higher nearer the centre and that the stress on the join between the bosses and the wheels will be high. I remember feeling sick on playground roundabouts as a kid and realising that if you had any chance at all of stopping it by putting your feet down it would be at the outside edge, not in the middle. In the present case, all the more so if the engine is a bit of a jerky runner. Tapping some holes wouldn't be a problem but I think I prefer your pins suggestion so I'll go with that. There would be something phoney about having screws that aren't actually acting as screws, after all. Pins will be more 'honest'.

SGW - I have seen that kind of pin before, when I dismantled an old car engine for fun and to get parts from to use in projects. They are really good and I can see that they would do the job very well. However, as I don't have any of them but do have some thin round silver steel bar, I'll use short lengths of that Loctited in as MJM suggests.

Thanks for your input, both.

 :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 05, 2020, 11:03:14 PM
I decided to make five holes through the boss and main body of each wheel to correspond with the five 'decorative' holes in the flywheels. To do this I mounted each flywheel in the small 4-jaw on the rotary table in the mill. I just used the setup as a circular vice, eyeballing the positions of the small holes, centre drilling then drilling them, and rotating the wheel by hand each time. I did it this way because I had to drill right through the wheel and If I had rotated the table I'd have fouled the chuck jaws with the drill.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/860613.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/860614.jpg)

The drill I used was chosen to allow an easy push fit of a spare piece of silver steel which I had in the shop:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/860616.jpg)

I cut the pins from the silver steel and then ground them roughly to length - or a little over - on the bench grinder, holding them in this vintage hand vice. I bought this vice in a second-hand emporium in Brighton while visiting my daughter there about a year ago. At the time I wondered if I would ever use it, and indeed I haven't used it a great deal but there are odd occasions like this where I wouldn't be without it:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/860618.jpg)

The pins in their rough form were fixed into the holes using Loctite 638...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/860624.jpg)

... and then the bosses were faced in the lathe:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/860626.jpg)

You will see from this last photo that there is still a lot of work in finishing these flywheels, with machining and chatter marks to face and polish out. However, the pinning operation completes them in their basic form, and overall I'm quite pleased with them. Much of the finishing will be done in situ on the crankshaft.

Meanwhile, I have been in planning mode, ordering some new tooling and making a list of materials that I'll need to continue with building the engine...
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on May 06, 2020, 07:16:30 AM
I'd have just stuck with the loctite unless your fit was really loose, plenty on here have made engines with bigger flywheels loctited together, often on crankshafts that also use loctite to make up the crankshafts or hold a crank disk to the shaft, in both cases the glue area is far smaller and stresses far higher
Title: Re: A Simple Uniflow Engine
Post by: Zephyrin on May 06, 2020, 08:12:37 AM
The annoying thing with these machining marks is that they tend to recur and even amplify on reworking.
you really have to change radically the machining routine, I suggest a very wide tool 10-12 mm and an ultra-slow speed, even turning by hand!

have fun with this new model!
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 06, 2020, 08:21:29 AM
@ Jason. I get what you are saying, and the fit was not that loose so I may well have got away with just the Loctite.

When MJM raised the question of pins his point was that pins may be required, not that they definitely would be. I just decided to play it safe and put the pins in so I wouldn't have to go back and do remedial work later if the Loctite failed. As a relative beginner I have never used pins before so it was good experience anyway.

Thanks for your thoughts, which are always worth hearing. Will bear what you say in mind when it comes to the crankshaft.

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 06, 2020, 08:26:14 AM
@ Zephyrin - thank you for this.

I have been using indexable carbide-tippped tools at high speed. The material appears to be quite a hard brass and it rang like a bell.

I'll look out one of my old wide-tipped HSS tools and try what you suggest - it has to be better than hours with sandpaper and scotch-brite!
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on May 06, 2020, 11:09:05 AM
Hi Gary, going well.  So much to learn about getting good surface finish, I will let others advise you on that one

You have done a good job on the pins.  There are always more than one solution to these problems, some are better that others but several will work.  As you say, having done it well will mean you are unlikely to have to do it again.  And itís another technique in your tool box.

MJM460
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on May 06, 2020, 04:22:30 PM
Garry, you might like to try some CCGT inserts rather than the CCMT that it look like you are using. These work very well on non ferrous materials and can take a lighter fine cut. failing that some sharp HSS, largest tool cross section you can fit and minimal overhang.
Title: Re: A Simple Uniflow Engine
Post by: crueby on May 06, 2020, 04:32:28 PM
Is there a good reference chart for all the initials in inserts?
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on May 06, 2020, 04:37:59 PM
I like the one in the MSC catalogue, this is the UK one but expect their US site has similar, you want page 380 & 391

https://edition.pagesuite.com/html5/reader/production/default.aspx?pubname=&pubid=9c3eabd2-e3ba-4a9f-8bd3-aa6475bd6e37
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 06, 2020, 05:19:12 PM
Thanks Jason -

I actually have some of the inserts for non-ferrous metals. They are silver in colour - I suspect they are CCGT but I will check.

It was my intention to us them for the finishing cuts on the wheels anyway, so I will give them a go in the first instance.

 :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 06, 2020, 10:23:40 PM
Just checked and the other inserts I have are indeed CCGT.

Will load one of them up and try a finishing cut with them on the flyheels.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 11, 2020, 11:11:46 PM
Well, that was easy enough to sort out. A CCGT insert with the lathe running at high speed and slow tool feed brought up a nice finish. Before and after shot below. Still some very minor machining marks - nothing I couldn't live with but I think they will polish out quite easily anyway :

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/861635.jpg)

Now, this engine will be all about symmetry. It will have two flywheels so it will also have two pulleys. I have a thing about flat belts and pulleys (have a million year project of building a lineshaft in my workshop in France...) so I thought I'd allow that obsession some breathing space in miniature here. I ordered some half inch flat belting from PM Research - not very cheap, especially with the shipping cost, but hey... Two pulleys were turned from aluminium on a Superglue arbour. The curved profile between the boss and the main part was formed using a round-tipped carbide tool. Here is one of them in its initial form on the arbour ...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/861636.jpg)

... and here it is having the hole for the locating screw tapped:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/861638.jpg)

Simple stuff, I know, to many of you guys out there, but this serves as a record of my build if nothing else.

The last photo of this session shows a quick mockup of the way that the flywheels and pulleys will be arranged on the crankshaft, bearing in mind (no pun intended) that the second flywheel and pulley will be arranged as the mirror image of this pair, with the crank between the two pulleys. That isn't the crankshaft they are on, btw - it's the Superglue arbour, just for demo purposes.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/861637.jpg)

The pulleys will need to be each given a slight crown for belt tracking purposes. In fact I did so on one of them but then decided to pause on that until a later stage when everything is running true on the crankshaft. I know that in esoteric old tomes there are formulae for the steepness of the crown on flat belt pulleys, but I reckon on something this small a 'suck it and see' approach is the way forward.

Next up is the crankshaft. That will be challenging new territory for me. Exciting though! I'm waiting for materials to arrive, hopefully in the next couple of days...
Title: Re: A Simple Uniflow Engine
Post by: Johnmcc69 on May 11, 2020, 11:32:49 PM
 :ThumbsUp:
 Great work Gary! Nice finish on the flywheel!

 John
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 11, 2020, 11:44:37 PM
Thanks John - very kind of you.

gary
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on May 12, 2020, 07:19:15 AM
Best way to keep the crown even is to set your topslide over a couple of degrees each way and taper the edges leaving the middle 1/3rd untouched then blend with a file. Wider pullies are best done in 5 sections.

(https://img.photobucket.com/albums/v156/jasonballamy/Engineering/EastonandAnderson/IMAG0873.jpg)
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 12, 2020, 09:44:37 AM
Jason -

I had made a start on one of my pulleys, and maybe even finished it (time will tell). I scribed a centre line then a line on either side of that 2mm from the centre line, i.e. leaving an unmachined crown of 4mm, so that would be almost 1/3. I also set the angle of the topslide to what I judged by eye would be about right but the protractor on my lathe is hard to read so I'm not sure what the angle was. The result was a very slight crown on the pulley. Whether it will be enough remains to be seen. If it works I'll be able to repeat the angle because I 'saved'' it on a separate protractor with the angle as yet unread by me but locked in position. That said, I'll check that protractor and if it's less than 2 degrees it will be easy enough to reset the angle and shave a bit more off the pulleys. My aim is to finish the crowns in situ on the crankshaft, at the same time as a final truing up of the flywheels.

Thanks for your interest and advice - much appreciated.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 12, 2020, 10:52:37 PM
The order of materials arrived today. Treasure!

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/861722.jpg)

Given that apart from the basic dimensions and layout of the working parts this engine will be scratch built, I couldn't be too sure about the types and sizes of stock that I will need, so I ordered on the basis of a semi-educated guess while still leaving scope for making things up as I go along. For that reason I won't be too specific at this point about what I think I might use for which parts, except for the 12mm diameter silver steel 4th from the right, which will be the crankshaft.

There are also a couple of other pieces of stock on the way from another supplier, and of course I already have some stock that I will add in as required..

You can be sure that I'll seek your advice when I need to!

I deliberately ordered quite liberally to give me plenty of choices. Some of it I may not use at all, and I hope that following the build I will have quite a lot of this left over for other projects.

Some new gear is on its way - hopefully it will arrive tomorrow. When it does I'll post some photos and then move on to the next stage of the build.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 15, 2020, 12:05:57 AM
More stock arrived today:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/862072.jpg)

Cast iron square bar - a foot each of 50mm and 60mm. Totally over the top for my current requirements, but I would like to use cast iron for a couple of parts of this engine and I couldn't decide which size to buy, so...

There will be plenty left over for future projects. I now have enough square cast iron bar to last me the rest of my life, and that is a good thing. I like to overbuy a bit when ordering materials as a way of building up some stock for inspiration and use in future projects.

This next bit wasn't part of my original plan for the cast iron, but in this excellent little book...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/862070.jpg)

... Alex Weiss says that cast iron is great for bearings if it is running against a hard steel. This is echoed by various sources online, and no doubt some of you will have thoughts about this too. This engine - as I envisage it - will need to have a split big end bearing as it will have a double-webbed crankshaft which will be closed in at both ends by the frame. It occurs to me that it will be a lot easier to make a split plain bearing out of a bit of the square cast bar with the bearing surface being part of the iron itself rather than make one that is similar but with a split bush machined out of bronze and the two halves fixed into the housing. I envisage something like this:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/862071.jpg)

As you will see, sharpies, graph paper and a failure to engage with the conventions of either CAD or engineering drawing are about as hi-tech as I get when it comes to drawing up plans. My sketch is not to scale and the proportions aren't definitive, and that can all be played with as I go along. My question really is whether or not this is a reasonable approach for the bearing in question. The only issue I can foresee is that when the bearing eventually wears, the whole thing will have to be re-done rather than  just replacing a bush, but then it will probably never run for long enough for that to happen anyway. However, you may be able to see issues that I don't, so I'd be grateful for any thoughts you may have before I commit...

Finally - to help me with all this, these arrived today:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/862073.jpg)

Self-explanatory to you guys I am sure. I have had a bit of a splurge, indeed, but these things will help me to up my game.

Getting serious now...

 8)
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on May 15, 2020, 07:23:42 AM
What do you intend to assemble the crankshaft with?

Put an internal fillet on those side projections to reduce possibility of stress fracture and just so it looks nice.

Never a fan of big boxy big ends as there is a lot of unbalanced weight flying around so some shaping would not go amiss

I've only used CI as a bearing in slow speed applications so can't give first hand on running it fast.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 15, 2020, 09:27:25 AM
Jason -

Regarding the speed issue - thanks. I will do a bit more research and of course other forum members may have views too. If I don't hear anything to say that I shouldn't keep the bearing in cast iron, I'll give it a try as worst case scenario it could always be modified later with a bronze bush if it fails.

Great idea about the internal fillet.

Agreed re the boxiness, and good point re the unbalanced weight. The rectangular shape in the sketch is just a starting point really. For example, there is much more cast iron below the split than there is above it, so I'll be reducing the size below the split. Some kind of tapering on the bottom part might look good, and some rounding of the top part too. I reckon on starting with regtangular to the point at which it's functional, then do some shaping to finish.

For the crankshaft I have 12mm silver steel, and was thinking about using rectangular section EN3B for the webs. That said I have some 3/4" square EN1A which could be nice for the webs in terms of the look, though on reflection that might be too narrow. I wonder if you or anyone else have any thoughts about these materials. As it's my first proper crankshaft I'll probably not go for a press fit, so Loctite it will be, possibly with pins (I know you said previously that pins shouldn't be necessary, but this will be a fast runner and I like to know that things are rock solid).

Thanks once again, and have a good day.

 :ThumbsUp:

Title: Re: A Simple Uniflow Engine
Post by: Jasonb on May 15, 2020, 01:24:03 PM
EN£ and silversteel will be fine, as you won't be soldering then you can harden and temper the pin Ok though you could get away with leaving it as supplied.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 15, 2020, 01:32:39 PM
Jason -

by EN£ (possibly a typo) do you mean that EN3B will be fine, or that either of the EN steels I mentioned would be fine?

I did consider silver soldering the crankshaft together. It would be more pleasing to me to do that than to Loctite it. However, my concern would be whether that could risk distorting it with the heat. Do you have any thoughts on that?

Thanks for your interest,

gary
Title: Re: A Simple Uniflow Engine
Post by: Alyn Foundry on May 15, 2020, 01:51:56 PM
Hi Gary.

You don't have to worry about cast Iron bearing to Silver Steel crankshaft....

xnL8h1em45o
My Robinson is 31 years old and has run 1000's of hours. Nary a sign of wear in either of the " mating " surfaces. The engine can run up to 500 RPM too.

I prefer Silver soldered cranks too.... ;)

QwlmaAIzUMU

Cheers Graham.
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on May 15, 2020, 04:24:25 PM
What sort of speed are you hoping for, I got the impression you were after a bit of a goer with flash steam?

EN3B will be fine for the webs. Reason for asking about assembly method is that you can't really have a hardened pin and silver soldered joints as you want the assembled crankshaft to cool slowly which will not harden the pin. For slower speeds you don't really need to think about hardening.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 15, 2020, 04:31:31 PM
Thanks Graham.

What a great-looking engine! That big end bearing looks to be pretty much what I have in mind. Most encouraging...  :ThumbsUp:

In the book I cited earlier, Alex Weiss says:

'Because of its in-built graphite content, cast iron is an excellent bearing material. In use with a steel shaft, the surface of the cast iron gains a tough glazed surface that is very wear-resistant. An additional advantage is that cast iron bearings will continue to operate satisfactorily even in conditions of poor lubrication, though this is no excuse for failing to provide an adequate supply. A relatively unique property of the material is its ability to be used in conjunction with itself. Thus, the cast iron slides of machine tools may rub against cast iron mountings or gib strips of the same material.'

I'm definitely going to give it a go, and am looking forward to machining the bearing. Exciting!

Thanks also for the link to your video of silver soldering a crankshaft. I will definitely not rule that out, and look forward to watching the video - which I will do later this evening. Expect a couple of new comments on your youtube channel...  :)

Out for a walk in the sunshine now, though.

Cheers,

Gary
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 15, 2020, 04:38:25 PM
What sort of speed are you hoping for, I got the impression you were after a bit of a goer with flash steam?

EN3B will be fine for the webs. Reason for asking about assembly method is that you can't really have a hardened pin and silver soldered joints as you want the assembled crankshaft to cool slowly which will not harden the pin. For slower speeds you don't really need to think about hardening.

The speed: tbh Jason I don't really know. I may in due course run the engine on flash steam when eventually I get my flash steam boiler done, but prior to that I may run it on something else. Speed per se isn't the issue for me - I was just attracted to the design, mainly because of its simplicity for a beginner like me. However, I am given to understand that it will prefer higher speeds, so I'll just wait and see what emerges.  :)

EN3B: good to know, thanks.

Thanks for your advice about the crankshaft. Noted. I may yet use silver solder. Graham's video - which I will watch later - may help me make up my mind. I'll either be inspired or intimidated... and probably a bit of both! But nothing ventured, nothing gained...

Cheers,

gary
Title: Re: A Simple Uniflow Engine
Post by: Alyn Foundry on May 16, 2020, 03:20:45 PM
Hi Gary.

Thanks for your comments on my YouTube channel....  ;)

The Robinson replica is 1 1/2" bore and 2" stroke.

The crankshaft is first centre spotted at both ends. If you noticed we started heating the main shaft from both ends, effectively " stretching " the metal evenly. Then you start increasing the heat where the joints are. We apply,  liberally the flux. Having tried many over the years I can totally recommend Tenacity number 5 for this job. Specifically designed for Silver soldering Ferrous materials.

We cut small sections of the Silver solder and put them at each joint. You probably noticed that one dropped away so sometimes you have to manually apply a little more.

Once cold the " bridge " is cut out and the whole assembly put into an Acetic acid bath for 24 hours to remove the flux residue.

Because of the " spotting " you can now " true up " any discrepancies in the lathe.

Just for fun....

37u1WruBMgU
Cheers Graham.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 17, 2020, 09:54:48 AM
Graham -

Many thanks for your detailed description of how to silver solder the crankshaft.

I'll give some thought to the question of siver soldering mine vs using Loctite.

As you don't mention pins, I presume you don't use any.

That Robinson is a beauty!

Cheers,

Gary
Title: Re: A Simple Uniflow Engine
Post by: Alyn Foundry on May 17, 2020, 11:37:10 AM
Graham -

As you don't mention pins, I presume you don't use any.

That Robinson is a beauty!

Cheers,

Gary

No pins Gary.    :)
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 17, 2020, 12:47:04 PM
Cheers Graham.

 :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on May 17, 2020, 01:09:37 PM
And just when you thought you had decided what way to do it someone comes along and says they use pins as they like to apply the solder to one side of the joint only it makes it a bit hard to tell how deeply it has flowed.

http://www.modelenginemaker.com/index.php/topic,2160.msg39156.html#msg39156
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 17, 2020, 01:29:35 PM
Right! That's it! I'm going back to stamp collecting...  >:(


Thanks Jason. Great post and pictures, which will be an excellent resource for me if I decide to use silver solder.

Your Galloway thread as a whole will be worth reading, I have no doubt. I have kept the tab open for later... :popcorn:

Hope you are having a good weekend.

gary

 :ThumbsUp:

Title: Re: A Simple Uniflow Engine
Post by: MJM460 on May 17, 2020, 01:54:41 PM
Hi Gary, while you are thinking about silver soldering, I will make a few comments on the overall project.

It is important to separate the ideas of flash steam and high speed engines.  Of course, the two are often associated in a project, and for quite valid reasons, but it is not necessarily so.

A flash steam boiler, sometimes called a mono tube boiler, is a boiler configuration that provides a quite  large heat transfer area for steam raising, with quite low weight for the steam production achieved.  But at the end of the day, the amount of steam raised is determined mostly by the burner, and how much fuel can be burned, so long as you have enough heat transfer area.  I was tempted to include the word efficiently in that sentence, but not all projects are interested in efficiency.  If someone wants to break a record, they want maximum power, and if burning more fuel, even less efficiently, achieves more power, then they go for it.

Part of the low weight is achieved at the expense of water capacity.  There is effectively no water storage in a flash boiler, so they canít be operated like my little boilers by filling up with water then lighting the burner and start steam production.  Well perhaps they could, but it would be a quite short run.  They really need a feed pump, preferably driven by the engine, but again it is not the only way.  The preference is because both steam consumption and water requirement, the same thing really, are dependent on engine speed, so while it is still not easy to balance the two, it is easier than if a separate pump is used.

Of course, the high power to weight ratio is very desirable for high speed vehicles, whether land based or water, and when combined with a very big burner, can produce awesome power to drive the engine.

But it does not have to be so.  If you use a quite moderate burner then you produce only the proportionate amount of steam.  You could build a quite moderate steam plant for a model boat for very sedate performance.  This approach has its own chapter in Benson and Raymanís excellent book, even though the rest of the book is a fascinating look into the world of high speed hydroplanes.  I think I remember you buying it, so you will be aware of the valuable information there.

In addition, it is not necessary for there to be no water storage.  A moderate plant can include a pressurised water tank, with an air cushion over the water, between the water pump and the steam coil.  It will smooth out the flow and give a bit of a safety factor against water failures, which might allow you to bring a model back to extinguish the burner.  A separate tank like this can allow design of the plant with a much lower centre of gravity than a more conventional boiler design, which is good for stability of a model boat.  Of course the fire tube marine boiler also has a good low centre of gravity.

The engine is a quite separate issue.  An oscillating engine as you have already built can operate quite slowly when required, particularly a twin cylinder double acting design which does not have the dead spots that the flywheel must supply the energy to carry through.  Similarly a slide valve engine, or any of the other designs we usually see on this site.  The upper speeds are mostly limited by the quality of balancing achieved, not easy with heavy reciprocating parts.  My mill engine achieves around 2000 rpm unloaded with quite low steam pressure, with limited balancing, but I suspect that even at this speed, wear might become an issue if I pushed it that fast for long.  So hardened pins and more attention to bearings might be required.

Slow engines are generally characterised by long stroke compared with the bore, though not necessarily so.  More significantly the steam is admitted mostly after the top dead centre, even when a little is admitted before.  Your engine with the inlet valve operated by a peg on top of the cylinder has the steam admitted equally each side of top dead centre. (I wonder how a double acting engine would be implemented).  More likely a twin single acting, or better still a three or more cylinder configuration with the cranks spaced equally around the shaft.  Because of this necessarily early admission, the engine needs to get enough of a kick every steam admission to accelerate the flywheel to store the energy necessary to push the piston over the next top dead centre position.  Otherwise the engine might just oscillate back and forth through about 340 - 350 degrees.  The engine will be happier going faster for this reason, but it still does not require the extreme speed sought by the racing community, it just wonít run slowly like your little oscillator.  But a quite interesting design, well worth trying.

So while roaring blowlamps, extreme pressure and temperature steam conditions, and high speed racing hydroplanes, are typically based of a flash boiler, uniflow engines, and very highly developed material selection, and manufacturing techniques, there is no reason why you cannot run your simple flash plant with a more moderate burner and your current engine, which might run quite happily around 1500 - 2500 rpm (at a wild guess) but definitely not slow like your oscillator.  Mind you, an oscillator is also is no slouch if you give it enough steam, as the oscillating engine design involves a much smaller oscillating mass than a typical mill engine, in both reciprocating and rotary motions.  Mine go at 2000 rpm measured with a digital tacho when unrestrained and with only the little meths burner, and are really not fussed at this speed.  Much less vibration than the mill engine.

It is one of those things that has to be tried, but if you can tackle a little engine driven pump, perhaps with bought gears, there is no reason that you could not try your flash plant with this new engine.  Keep the burner relatively gentle until you get the feel of it.  But I really would not recommend the flash plant with a hand pump only, unless you have plenty of water capacity.  It all comes back to heat balance.

By the way, stamp collecting is only allowed during the current lockdown situation, and there is another current thread where that can be included.  In the mean time you have an an engine and flash boiler to complete!

MJM460

Title: Re: A Simple Uniflow Engine
Post by: Jasonb on May 17, 2020, 02:27:04 PM
But I bet Garry has his heart set on a flash steam setup like this :LittleDevil:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/44290/860506.jpg)

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 17, 2020, 04:43:47 PM
I do  indeed, Jason.

But I also have my heart set on far too many other things. Funnily enough, stamp collecting hasn't featured among these for more decades than I care to remember. And flower pressing has never been on my list.

But yes - I would love to build a kickass flash steam plant. Equally, I would like to build a big, slow, lazy mill engine. And a beam engine. Maybe with a bit of a contemporary feel to the styling. And perhaps one or two bigger boilers.That's already quite a list alongside a bunch of other, non-steam related pipedreams.

But right now my heart is set on some ice cold cider and some burning BBQ charcoal, so to do MJM's post justice I shall read and respond to it later.

Cheers Guys, and thanks for your support.

 :cheers:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 18, 2020, 10:06:54 AM
Hi Gary, while you are thinking about silver soldering, I will make a few comments on the overall project.

It is important to separate the ideas of flash steam and high speed engines.  Of course, the two are often associated in a project, and for quite valid reasons, but it is not necessarily so.

A flash steam boiler, sometimes called a mono tube boiler, is a boiler configuration that provides a quite  large heat transfer area for steam raising, with quite low weight for the steam production achieved.  But at the end of the day, the amount of steam raised is determined mostly by the burner, and how much fuel can be burned, so long as you have enough heat transfer area.  I was tempted to include the word efficiently in that sentence, but not all projects are interested in efficiency.  If someone wants to break a record, they want maximum power, and if burning more fuel, even less efficiently, achieves more power, then they go for it.

Part of the low weight is achieved at the expense of water capacity.  There is effectively no water storage in a flash boiler, so they canít be operated like my little boilers by filling up with water then lighting the burner and start steam production.  Well perhaps they could, but it would be a quite short run.  They really need a feed pump, preferably driven by the engine, but again it is not the only way.  The preference is because both steam consumption and water requirement, the same thing really, are dependent on engine speed, so while it is still not easy to balance the two, it is easier than if a separate pump is used.

Of course, the high power to weight ratio is very desirable for high speed vehicles, whether land based or water, and when combined with a very big burner, can produce awesome power to drive the engine.

But it does not have to be so.  If you use a quite moderate burner then you produce only the proportionate amount of steam.  You could build a quite moderate steam plant for a model boat for very sedate performance.  This approach has its own chapter in Benson and Raymanís excellent book, even though the rest of the book is a fascinating look into the world of high speed hydroplanes.  I think I remember you buying it, so you will be aware of the valuable information there.

In addition, it is not necessary for there to be no water storage.  A moderate plant can include a pressurised water tank, with an air cushion over the water, between the water pump and the steam coil.  It will smooth out the flow and give a bit of a safety factor against water failures, which might allow you to bring a model back to extinguish the burner.  A separate tank like this can allow design of the plant with a much lower centre of gravity than a more conventional boiler design, which is good for stability of a model boat.  Of course the fire tube marine boiler also has a good low centre of gravity.

The engine is a quite separate issue.  An oscillating engine as you have already built can operate quite slowly when required, particularly a twin cylinder double acting design which does not have the dead spots that the flywheel must supply the energy to carry through.  Similarly a slide valve engine, or any of the other designs we usually see on this site.  The upper speeds are mostly limited by the quality of balancing achieved, not easy with heavy reciprocating parts.  My mill engine achieves around 2000 rpm unloaded with quite low steam pressure, with limited balancing, but I suspect that even at this speed, wear might become an issue if I pushed it that fast for long.  So hardened pins and more attention to bearings might be required.

Slow engines are generally characterised by long stroke compared with the bore, though not necessarily so.  More significantly the steam is admitted mostly after the top dead centre, even when a little is admitted before.  Your engine with the inlet valve operated by a peg on top of the cylinder has the steam admitted equally each side of top dead centre. (I wonder how a double acting engine would be implemented).  More likely a twin single acting, or better still a three or more cylinder configuration with the cranks spaced equally around the shaft.  Because of this necessarily early admission, the engine needs to get enough of a kick every steam admission to accelerate the flywheel to store the energy necessary to push the piston over the next top dead centre position.  Otherwise the engine might just oscillate back and forth through about 340 - 350 degrees.  The engine will be happier going faster for this reason, but it still does not require the extreme speed sought by the racing community, it just wonít run slowly like your little oscillator.  But a quite interesting design, well worth trying.

So while roaring blowlamps, extreme pressure and temperature steam conditions, and high speed racing hydroplanes, are typically based of a flash boiler, uniflow engines, and very highly developed material selection, and manufacturing techniques, there is no reason why you cannot run your simple flash plant with a more moderate burner and your current engine, which might run quite happily around 1500 - 2500 rpm (at a wild guess) but definitely not slow like your oscillator.  Mind you, an oscillator is also is no slouch if you give it enough steam, as the oscillating engine design involves a much smaller oscillating mass than a typical mill engine, in both reciprocating and rotary motions.  Mine go at 2000 rpm measured with a digital tacho when unrestrained and with only the little meths burner, and are really not fussed at this speed.  Much less vibration than the mill engine.

It is one of those things that has to be tried, but if you can tackle a little engine driven pump, perhaps with bought gears, there is no reason that you could not try your flash plant with this new engine.  Keep the burner relatively gentle until you get the feel of it.  But I really would not recommend the flash plant with a hand pump only, unless you have plenty of water capacity.  It all comes back to heat balance.

By the way, stamp collecting is only allowed during the current lockdown situation, and there is another current thread where that can be included.  In the mean time you have an an engine and flash boiler to complete!

MJM460


Thank you for this, MJM.

Although I was aware that the uniflow engine could be appropriately paired with a flash boiler (and have indeed considered that option), I didn't choose to build this engine with that specifically in mind. Another - quite separate - boiler development is on the cards. More of that later.  ;) 
However, irrespective of that, it would make sense for me to try running the engine on the flash boiler once they are both complete, but with the following caveats:

First - I may be wrong, but I have a feeling that the engine may require a bigger coil in the flash boiler than the current one as the cylinder bore will be either 30 or 35 mm. Fairly chunky. That said, I understand that coils are considered to be a consumable, and it wouldn't cost much in terms of time or money to twist up a bigger one.

Secondly (and this is a somewhat bigger issue) - I have gathered from the literature that a displacement lubricator won't work with flash steam as superheated steam is too hot to condense within the lubricator and will go straight through to work its mischief on an unlubricated piston and cylinder.  The thing is that I'm not really sure that I want to put my energy into building a mechanical lubricator, at least at this point. One could then legitimately ask why I decided to start building a flash steam boiler if  this is the case. The answer would be that the flash boiler is really a kind of side project for me, something that is motivated more by in-the-moment curiosity than by a clear sense of purpose, built as cheaply as possible and to fill gaps between other projects over a longer period of time. One of those, you know...

I have no plans to build model boats or vehicles - it's stationary engines and boilers that most interest me (though to build an engine that would drive a real small boat would be exciting!). However, I do like the idea of using the pressurized reservoir with air cushion, as mentioned by you  above and as we discussed at the start of my flash boiler thread. That said, unless there is a way round the oil pump vs displacement lubricator issue (and if anyone knows of such it will be yourself!) then the likelihood is that I won't be running anything on flash steam any time soon and that another boiler will be used to drive the uniflow engine on non-superheated steam in the first instance.

I suppose I could always hire out the flash boiler (in its semi-complete state) to philatelists looking for more efficient ways of steaming stamps off envelopes. Or if not more efficient, certainly more powerful ... :Lol:

Thanks as always for your very knowledgeable input.

gary

Title: Re: A Simple Uniflow Engine
Post by: MJM460 on May 20, 2020, 10:12:13 AM
Hi Gary, I would not want to discourage you from your intended course, and I look forward to seeing the new boiler develop.  These are after all, affairs of the heart, and no one else can dictate where we should go. 

However, in the interests of increasing understanding, I hope you will bear with me while I explore some of the issues in your caveats.

The first one introduces a whole bagful of interesting issues.

First, how much steam will your uniflow engine actually need?  The valve principle is actually very different from oscillating or slide valve engines we all normally think about.  The valve is only open for the short time the piston crown is touching that peg which protrudes into the cylinder.  And there is a whole chain of dimensions determining that time, each with its own tolerance, which can accumulate to make the actual time difficult to determine, however, that is not the aspect I mean.

When the usual valve first opens there is an initial inrush of steam to equalise the pressures, then the continuing downward travel of the piston under the influence of the steam pressure, does the work that turns the engine.  But consider the uniflow!  When the valve opens, the piston is travelling up!  Still might be that initial inrush, or might not if the steam remaining in the cylinder after the exhaust closes off is compressed up to pressure by the time the inlet valve opens, but then the engine does work on the steam (it comes from the flywheel slowing) for fully half the time the valve is open.  Think of that for a moment, for fully half the valve opening time, the volume in the cylinder is reducing and only the pressure balances with that in the boiler.  Then steam enters through the now fully open valve and while the pistons goes down until the valve closes, I assume at about 1/4 of the stroke, quite early cut off for any engine, and then takes advantage of the expansion of the steam in the rest of the stroke until the exhaust opening lets enough steam out to lower the pressure again for the return stroke.  Because this engine really does utilise the steam expansion, so I expect it will be quite miserly in its steam consumption.  It is that requirement for the flywheel to do the work before top dead centre that is why the engine will probably need to run faster than typical on this site.  The flywheel needs plenty of stored energy for the non-power parts of the cycle.  Similarly you might need a bit higher steam pressure than is required to run your oscillator.

The next issue is how much coil length to generate the required amount of steam?  Again, first it is important to recognise that the steam produced by a boiler is fundamentally determined by the heat released by the burner.  The efficiency of the boiler is a secondary, but still important consideration.  That efficiency is again determined primarily by the heat transfer area, with other arrangement factors secondary.  My little boilers seem to run at around 60 to 70% for example.  The amount lost goes mostly up the stack in the heat of the flue gas, and is unavoidable.  A much smaller amount is lost from the casing, and this can be minimised by insulation.  There is a lot of variation in the acceptable heat transfer area, but if you calculate it for your vertical boiler, it will give you an idea.  If your coils has less heat transfer area, more heat will be lost up the chimney in the form of higher flue gas temperature, but if more area, then less loss, but it is diminishing returns.  As the steam gets hotter so the temperature difference from the flue gas gets less, you need increasingly more area to get the next little bit of improvement.

As for the coil being disposable, I think that is probably more in the context of those extreme hydroplanes, where they melt copper tubing so have to go to stainless steel, and quite likely push the limits of that.  A more moderate firing rate should allow copper to last as well as your vertical boiler.  But you are also right in assessing that a new coil costs a lot less in material and effort than a conventional boiler, and that is part of the attraction of the concept for moderate applications, while the light weight relative to the steam produced is a major factor for chasing speed.  If you put a little meths burner under your coil, it will not melt the copper, and the displacement lubricator will work just as on my pot boiler.  There is a lot of space between those extremes.

So quite a lot in that first caveat

The second point, about lubrication, is also important and has to be taken into account also for air running if long running hours are required.  It is true that if the displacement lubricator gets too hot, the steam does not condense, and no oil is displaced into the steam pipe.  However, while the jump to an oil pump is necessary for the chasers of extreme, and I am told that the little oil pumps are not very difficult, though I have not yet tried one, there are also a few tricks you can do with a displacement lubricator in a moderate plant if the degree of superheat prevents the lubricator from working.  If you use a steel washer in the connection between the lubricator and the steam pipe, it conducts a little less heat than brass in contact.  And a fibre washer even better.  You can also add some cooling fins to the lubricator body to increase the heat loss.  These require a bit of trial and error with only short runs until you are getting an amount of water accumulating in the lubricator.  Certainly we overlook lubrication at our peril, and as the burner gets bigger, the pump solution becomes preferred.

Regarding your last comments, who among us has not at some time felt ďso many projects, so little timeĒ, and those high speed hydroplanes look like wild beasts.  But I suspect we both need to learn a lot more about more moderate plants before we chase that dream too far.  But one day.....

So donít let me deflect your plans, but it is always useful to have a few more ideas in the tool box for the day they might come in handy, they arenít very heavy.

MJM460

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 21, 2020, 12:30:54 AM
MJM -

Indeed, ideas are not too heavy to carry around. What you have said about ways to make a displacement lubricator work with a monotube boiler (I won't use the term 'flash' here because I understand that the coil can deliver steam at lower temperature) is encouraging, and I will plooter away with the flash/monotube boiler over time alongside other developments. I have no major objection to the idea of building an oil pump other than time and how I want to spend it, but it's nice to know that there are other options too. I had a feeling you would come up with something!

If I understand you correctly, it would seem that the uniflow engine may not demand much steam but that the steam it does use will need to be at high pressure. How that would translate into performance on the coil I have already made will be (for me at least) a matter of trial and error. I take your point about these coils only being a consumable when pushed to the extreme - that makes sense. However, if I found that I needed a bigger coil it wouldn't be a big job to make one. Which I suppose could in turn require a more powerful lamp... we shall see.

All this said, another boiler solution is waiting in the wings. It may seem unnecessarily coy but I'd rather not explain until it's a reality. It will certainly make a difference to he options for running this and other engines though.  Which doesn't mean that the flash boiler will be cast aside unfinished, but it does mean that I'll be able to take my time with it.

 :)
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on May 21, 2020, 01:02:00 AM
Started work on the two main bearings between the crankshaft and the sides of the frame. Still very much a beginner but now learning to up my game by using my new 4-jaw independent chuck clocked with a DTI to minimise runout instead of the 3-jaw and crossed fingers:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/863202.jpg)

Hopefully this will result in a better engine at the end of the day.

I have also just accquired two of these for parting off - one 2mm and one 3mm:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/863203.jpg)

The 2mm tool sliced through the bronze with very little effort and minimal anxiety on my part! Very nice to use, but counterintuitive how that insert stays in place I reckon.

gary

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 04, 2020, 12:33:21 AM
Unfortunately I had a dig-in and mangled the first of the two main bearings, so I put the stock for the bearings aside and ordered some tooling to make the job easier. I switched my attention to making two bronze collars (yay! for ER-32 collet blocks!) ...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/865622.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/865623.jpg)

... and two cast iron thrust collars:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/865624.jpg)

Here they are, temorarily rigged up on the crankshaft-to-be for demo purposes:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/865625.jpg)

Outboard of each flywheel the cast iron thrust collar will run against the bronze face of the main bearing. The bronze collars are situated between the pulleys and the crank webs, mainly just for the look. I somehow managed to screw up the crank webs by making holes that are out of parallel, so the ones you can see in the picture are destined for the scrap bin and new ones will be made.

Pausing there while waiting for more steel, I began work on the cylinder, which will be of cast iron. I started by squaring a block of the stuff with a facemill and a large endmill:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/865626.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/865627.jpg)

The cylinder block was then chucked in my new self-centring 4-jaw and clocked in as closely as I could get it (with the aid of a rubber mallet):

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/865628.jpg)

This was my first ever experience with a self-centring 4-jaw and I was impressed by how solidly it holds a square workiece.

The cylinder bore was then started with a centre drill and a succession of twist drills...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/865629.jpg)

... and then bored to size (35 mm):

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/865630.jpg)

It remains chucked in the lathe as I type. The bore still needs a finishing cut, after which it will be honed. The outside of the block will be given some profiling and the surface finish will need more work.

All in all, some progress, despite a couple of frustrations...

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 08, 2020, 10:06:37 PM
The basic bore of the cylinder is now complete. 35 mm (approximately):

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/866414.jpg)

The picture below shows the bore, with the cylinder silhouetted against the evening sky. There are obvious machining marks. I don't know what you guys will think, but I feel quite pleased with the internal finish given that I used a toolpost-mounted boring bar, albeit a fairly rigid one. The marks are not deep and the pattern is regular. I have ordered a cylinder hone and some honing oil and I'm hoping that will take care of the internal surface:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/866413.jpg)

I'm hoping that the hone arrives tomorrow. The external surface of the block needs more work.

So, in the absence of a hone, I then started on the cylinder end cap. This will also be square-ish in form and will be bolted to the cylinder but will be visually continuous with it. It will be bolted in situ when I profile the outside of the cylinder block so that the two parts can be milled to shape simultaneously. The cap will have a raised boss on the inside to locate it in the end of the cylinder. It will be drilled and tapped in the centre to accept the steam inlet valve. In this photo I have made a start on turning it down but I thought I'd better stop for the night as the neighbour's kids are probably trying to sleep.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/866412.jpg)

I enjoy machining cast iron but it's a messy old game. Major cleanup required...

Cheers,

gary
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 16, 2020, 12:16:49 AM
While waiting for the cylinder hone, I made a start on making some new crank webs. The ones I made before were no good as the holes were out of parallel. I will have to find out where the origin of that problem lies. Meanwhile, though, I have decided to try making a new pair on the mill. I used superglue to fix two pieces of the steel bar together so that they can both be drilled and reamed at the same time:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/867313.jpg)

In the picture it looks like they are not fixed together, but they are. The effect is just because the ends hadn't been squared off when I took the photo. Both ends of the temporary assembly have now been milled square ready for drilling and reaming in the mill. Once that is done I'll use heat to break the superglue bond.

However, these arrived today...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/867312.jpg)

... so it's back to the cylinder. I have never set eyes on this type of hone before, and the stones on the hone are much smaller than I thought they would be, but no problem. I made a start with the honing, the hone being held in a hand drill and the cylinder in the vice:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/867311.jpg)

The bore is coming up with a nice satin finish, but some machining marks are still visible and there is a bit of surface unevenness about halfway down the bore that I can actually feel with my fingertip, albeit slightly. I don't know how much of an issue this is as I'm hoping it will hone out, but I decided to pause with the honing and make a dummy piston out of a piece of scrap brass to test the overall straightness and regularity of the bore. There's no point in further obsessing with the hone until I have checked that the bore is basically true and parallel, and I think the dummy piston will be a good way to gauge that.

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 16, 2020, 10:18:59 PM
The next step was to finish the basic form of the cap. It has a spigot which fits the bore fairly snugly. The cap will be bolted to the end of the cylinder and the edges will be milled in situ to create visual continuity between the cylinder block and cap:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/867401.jpg)

In his design, Stan Bray suggests a shop made ball-bearing type check valve as the main steam inlet valve to the cylinder.  I'm not such a purist that I feel compelled to make fittings of this kind when they can be bought from a supplier. I'm using a ready-made check valve sized for 1/4" OD pipe. The cap will be drilled and tapped for this valve, but the photo below shows a mockup of the arrangement just to give an idea:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/867404.jpg)

It was then time to test the cylinder. I turned down a piece of brass on a superglue arbour (yay, Clickspring!) to make a dummy piston:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/867403.jpg)

Then, with my heart in my mouth I anointed it with steam oil and pushed it into the bore:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/867402.jpg)

Amazing! My fears of a crooked bore and jamming were unfounded. The dummy piston behaved in the cylinder just like a real piston should. Smooth action (well, just a couple of very minor tight spots but these will disappear). When I put my hand over the open end where the cap will be, the piston pulled a formidable vaccuum.  :cartwheel:

Well pleased with that and tbh I don't feel inclined to obssess much more about the finish of the bore. Once I have drilled the steam exhaust ports I'll give the bore another quick go with the hone and try to achieve the desired cross-hatch pattern, but I'm pretty sure the thing would run fine as it is. In fact I think  that the real piston can afford to be a tiny bit bigger in diameter for even better performance.

The exterior of the cylinder requires more work, mainly of a cosmetic nature. More of that later...

Now, a question: can any of you advise me on my choice of material for the piston? I have round bar of sufficient diameter in cast iron and free machining stainless . I'd be happy to buy something else if needs be, but I suspect I don't need to. I'm aware that cast iron is an exception to the rule about using dissimilar metals together, and I also understand that stainless works fine with cast iron too. Which would you guys recommend?

Also, I'll be quite happy not to use ring(s) of any kind on the piston, though wouldn't mind cutting an oil groove or two in it. However, I'm happy to change my mind in response to advice. Any thoughts?

gary
Title: Re: A Simple Uniflow Engine
Post by: john mills on June 17, 2020, 12:07:21 AM
you have a cast-iron cylinder then the material to use is cast iron .
Title: Re: A Simple Uniflow Engine
Post by: Johnmcc69 on June 17, 2020, 01:34:21 AM
you have a cast-iron cylinder then the material to use is cast iron .
But wouldn't SS be better for corrosion resistance?

 My edit: Nice work Gary!

 John
Title: Re: A Simple Uniflow Engine
Post by: john mills on June 17, 2020, 06:51:35 AM
the cylinder is already cast iron so the same care for the cylinder already if you don't want corrosion then cylinder out of bronze  piston bronze too soft packing will serve well .with cast iron then cast iron piston rings rusting is can be a problem.   
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 17, 2020, 10:45:48 PM
Thank you both.

I think I'll probably go with a cast iron piston. As john mills notes the cylinder is cast iron so it will be vulnerable to corrosion anyway. I'll just have to keep it dry and oiled when not in use.

I'd rather get away without piston rings if possible. Would just having a plain cast iron piston with maybe oil grooves but no rings be viable or would the absence of rings have a very detrimental effect? If any rings are necessary I'd prefer to go with silicone or viton ones (whichever it is), but would prefer not to use them if possible. I'd welcome any further thoughts on this. The cylinder bore is about 36 mm.

Meanwhile, this evening - a fair bit of thinking done but only modest progress in practical terms. I drilled two exhaust ports through the cylinder walls into the bore, then gave the bore a light honing to remove any burrs, after which I marked out (by hand) and punched for a bolt circle to which the cap will be fixed in due course:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/867600.jpg)

 This is a x 3.5 scale-up from Stan Bray's plans, but his small original version has one exhaust port of the same size as these. His advice is to keep the same size of exhaust port in scaled up versions but to make more of them, so I stuck to his original size but drilled two of them, one on each side of the cylinder. If these turn out to be insufficient I can always drill a third one on the top of the cylinder. The idea is to eventually make a manifold of some kind to connect the exhaust ports together.

Regarding the bolt circle, the bottom right punch mark in the photo is a bit out of alignment. I fixed that after the photo was taken.
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on June 18, 2020, 07:10:14 AM
If you are not going to put the engine to much work then you can run it without rings, easy enough to enlarge one of the oil grooves for a Viton ring if you find you want one at a later date.

Not enlarging the holes is probably more to do with timing so you could put them side by side which may help reduce the number of pipes to couple them up
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 18, 2020, 08:32:36 AM
Great idea on the viton ring, Jason. Thanks. Not sure how much work it will do, but I'd like it to do some I think. One step at a time as you suggest sounds sensible.

I have already drilled the exhaust holes on opposite sides of the cylinder with the possibility of a third one on top. I'm ok with that though as I have a half-formed picture in my mind of a funky-looking manifold that could be quite a visual feature if I get it right.

Any advice from anyone on depth, width, number, spacing and profile of oil grooves in the piston would be welcome.
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on June 18, 2020, 10:06:00 AM
I usually do 3 @ about 0.5mm deep equally spaced along the piston
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 18, 2020, 10:07:14 AM
Ok ta.

Maybe with a parting off tool?
Title: Re: A Simple Uniflow Engine
Post by: john mills on June 18, 2020, 10:46:28 AM
hi Gary

i would make the grooves a little deeper ,they will work to reduce leakage and the engine will run.I have an engine running with a larger bore has been running with out rings just the grooves and it runs 0k.you can always try running and add rings latter  .    I would use a grooving tool you have that will let you fit number of grooves across the piston if it is a parting tool that would do.
             John
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on June 18, 2020, 11:15:08 AM
Hi Gary, another vote for no rings, just plain grooves.  I have done this on each of my engines and they all run quite well.

In large compressors, there is one at least one brand of oil free reciprocating compressors which has no rings even for high pressure hydrogen.  They have a series of square grooves with no rings or packing.  Admittedly more rings than you would want, but the principle is called a labyrinth compressor.

Basically, the gas or steam passing between the piston and cylinder reaches a groove, it expands into the groove, with a consequent pressure loss.  It then has to accelerate into the passage again.  So generally more resistance, and consequently less bypass than a plain piston.

I tend to use about 1.5 mm wide and deep, as I have a suitable tool for those.  And two or three depending on the length of your piston and what will fit.  Whether it is really the labyrinth effect, or the effect on the oil film, or even if a plain piston would be just as good, I donít really know.  It would probably be necessary to rig up some sort of flow test, but it would need quite accurate instrumentation.

I always have it in mind to add some graphiteís yarn some time to see if this makes a difference, but my observation so far is that the engines run well without it. 

The same principle where the piston rod passes through the gland, though there, I generally return and add theming of graphited yarn, which definitely reduces the leakage.  Just the annulus between the piston and cylinder has a larger cross sectional area for flow than the gap around the piston rod.

With your nicely fitting piston, I would just cut the grooves and not worry further.

MJM460
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on June 18, 2020, 01:20:06 PM
For smaller engines I use vee grooves, same as found on thousands of Stuart 10 series engines so proven to work.


Most of the 24mm ones I have been designing over the last few years have a single O ring groove cut but have not found the need to fit the actual rings ( do on the IC engines)
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 18, 2020, 09:14:20 PM
Thank you guys - that gives me plenty to go on.

 :ThumbsUp: :ThumbsUp: :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 28, 2020, 09:39:18 PM
Meanwhile, still on the cylinder.

Eight holes for the bolt circle were drilled and tapped M5, and transfer screws were used to mark out their positions on the inside of the cap:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869030.jpg)

The edges of the cap were milled to size in situ on the cylinder body:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869029.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869028.jpg)

I think (hope!) that the cylinder would be functional in its present state with the addition of the valve, but there is still a fair bit of work of a cosmetic nature to be done on the outside of the cylinder block.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 29, 2020, 11:37:45 PM
A corner-rounding endmill was used to...er... round the corners:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869192.jpg)

Sorry about the grainy picture quality there.

This was done with the cap in situ. Some sanding was then carried out using 180 grit wet and dry paper with cutting oil on the surface plate. This made a difference quite quickly:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869191.jpg)

There is stilll more sanding to go to achieve the finish I want.

Now, once again, I seek your advice. I do not wish to paint this engine. How realistic is it to leave the cylinder  (cast iron as it is) untreated and just given an occasional light smear of oil to keep it from rusting? If that's not a good idea, I wouldn't mind blackening it with the chemical product called 'Black-it', though that's quite an expensive option. Do any of you know of any other ways to treat cast iron? I would be happy to hear of anything innovative to give it an interesting surface patina or colour...
Title: Re: A Simple Uniflow Engine
Post by: Admiral_dk on June 30, 2020, 11:49:04 AM
You are doing good so far  :ThumbsUp:

Have a look at how Chris Nickle plate iron - simple and without any problematic chemicals.

Best wishes

Per
Title: Re: A Simple Uniflow Engine
Post by: crueby on June 30, 2020, 02:53:07 PM
I have electroplated nickel onto steel, never tried it on cast iron, seems like that would work too. It would not give the black color you want, though.
Title: Re: A Simple Uniflow Engine
Post by: Johnmcc69 on June 30, 2020, 08:49:43 PM
Over at the "other place" (HMEM)  :paranoia: there is a fellow building G. Britnell 's beautiful Holt model. He has been using some gun bluing solutions from "Brownells" with some really stunning results....
 Not sure how those solutions work with CI, or cost, but it adds an aged patina that looks great on that engine.

 Additionally, bead/sand blasting adds a nice "as cast" appearance.

 Nice work on that cylinder Gary!

 John
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 30, 2020, 10:50:03 PM
Many thanks Gentlemen.

@Chris - would you mind telling me which thread of your prolific output contains the nickel plating? I'm not necessarily seeking a black finish.

@John - beadblasting... now that has some appeal, for sure.

Will think about the options...

gary

 :ThumbsUp: :ThumbsUp: :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: crueby on June 30, 2020, 11:12:04 PM
It was over on the Marion Valve Engine build thread, here:
Started here, with link to the instructions I followed:
https://www.instructables.com/id/High-Quality-and-safe-Nickel-Plating/
http://www.modelenginemaker.com/index.php/topic,9312.msg210244.html#msg210244 (http://www.modelenginemaker.com/index.php/topic,9312.msg210244.html#msg210244)
More a few posts after that one, and here too
http://www.modelenginemaker.com/index.php/topic,9312.msg210244.html#msg210244
Its quite easy to do, I recommend getting a variable power supply if possible so you can adjust the voltage - higher is quicker, but rougher finish, around 6 volts is good. The distance to the part changes it too, the closer the faster/rougher. Distilled water, non-iodized salt, a Nickel rod/plate for a source, and a plastic container are the only other parts you need. No nasty acids involved, and you can re-use the solution so a lidded container is handy to store it in. I've since done a bunchof knobs for the Lombards up at the museum, as well as parts for several models. After plating, you can buff the plating to shine it up.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 30, 2020, 11:22:45 PM
Over at the "other place" (HMEM)  :paranoia: there is a fellow building G. Britnell 's beautiful Holt model. He has been using some gun bluing solutions from "Brownells" with some really stunning results....
 Not sure how those solutions work with CI, or cost, but it adds an aged patina that looks great on that engine.

 John

John - I had a look and I think I found it - about half way down this page (by Mark T, or 'dnalot'):

https://www.homemodelenginemachinist.com/threads/marks-holt-75.31650/page-11

Very handsome it certainly is. Might well be worth  investigating gun bluing solution...

 :ThumbsUp:

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on June 30, 2020, 11:28:51 PM
It was over on the Marion Valve Engine build thread, here:
Started here, with link to the instructions I followed:
https://www.instructables.com/id/High-Quality-and-safe-Nickel-Plating/
http://www.modelenginemaker.com/index.php/topic,9312.msg210244.html#msg210244 (http://www.modelenginemaker.com/index.php/topic,9312.msg210244.html#msg210244)
More a few posts after that one, and here too
http://www.modelenginemaker.com/index.php/topic,9312.msg210244.html#msg210244
Its quite easy to do, I recommend getting a variable power supply if possible so you can adjust the voltage - higher is quicker, but rougher finish, around 6 volts is good. The distance to the part changes it too, the closer the faster/rougher. Distilled water, non-iodized salt, a Nickel rod/plate for a source, and a plastic container are the only other parts you need. No nasty acids involved, and you can re-use the solution so a lidded container is handy to store it in. I've since done a bunchof knobs for the Lombards up at the museum, as well as parts for several models. After plating, you can buff the plating to shine it up.

Chris - thanks for this. Yes, it looks good. And that engine it's on is a beauty. Not sure if nickel plating is for this here cylinder of mine, though not ruling anything out at this stage...

 :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: crueby on July 01, 2020, 12:50:45 AM
This conversation got me curious about whether the plating would work on cast iron - so, took the piece of Durabar that I have, stood one end into the container and hooked it up for a while:
(https://i.postimg.cc/y8bQJGHv/IMG-7277.jpg)
Thats an official 'Yup - it works!'. Shows the angle it was at in the liquid nicely! Raw iron on the left, nickel plated on the right.
Title: Re: A Simple Uniflow Engine
Post by: Jasonb on July 01, 2020, 08:10:55 AM
Wipe down with an oily rag after running and drying will do unless you store the engine in adverse conditions. After all the inside is bare iron and won't be getting any additional coatings.

Biggest problem I can see if plating the cylinder is keeping the bore free of plating.
Title: Re: A Simple Uniflow Engine
Post by: crueby on July 01, 2020, 01:17:42 PM
Wipe down with an oily rag after running and drying will do unless you store the engine in adverse conditions. After all the inside is bare iron and won't be getting any additional coatings.

Biggest problem I can see if plating the cylinder is keeping the bore free of plating.
Vinyl tape on any portion keeps it clear of plating, could put a piece over the ends of the bore to seal it off. Or put the cylinder caps on.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 01, 2020, 01:33:01 PM
Well, guys - this is exactly the kind of discussion I was hoping for when I asked the question.

Chris - your nickel plating looks great and clearly works on cast iron. I'll keep the idea in mind for future projects. However, I have decided to give the gun blue (as suggested by John) a go as it's more what I'm aiming for in this application, so I ordered a tub of this:

https://www.amazon.co.uk/Bisley-Gun-Blue-75g-Tub/dp/B00H5LRDKC/ref=sr_1_1_sspa?dchild=1&keywords=gun+blueing&qid=1593606391&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUE1SExURE4ySkpMR1omZW5jcnlwdGVkSWQ9QTAxODY1ODkyWDIzRTMyRk0yMFAmZW5jcnlwdGVkQWRJZD1BMDQ4NDQzNjNOVFlDVVA5NjQ1T0Umd2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

It should be easy enough to manage as it comes in the form of a gel, and at less than a tenner a tub it doesn't represent a big risk.
Title: Re: A Simple Uniflow Engine
Post by: crueby on July 01, 2020, 03:55:40 PM
Looking forward to seeing how it looks. As I recall blueing chemicals work on iron and steel, not well on most stainless steel. Great way to get the color without adding thickness.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 01, 2020, 08:30:08 PM
Yeah - it will be interesting. I get the impression that the colour ranges from dark blue to black, depending on number of applications, etc.

Will be pleased if I can hold it to a nice dark blue but we shall see...
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 05, 2020, 10:18:38 PM
Drilling and tapping the cylinder cap for the valve.

This obviously had to be concentric with the bore. After remounting the cylinder in the lathe and watching it wobbling around, I decided to do it in the mill instead.
 I used a new toy - a coaxial centre indicator - for the first time:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869932.jpg)

Before plugging it into the mill spindle, I opened the box and showed it to my good lady, who said 'it looks like a piece of medical equipment'. I agreed with her on that point, and quickly took it back to the workshop so as not to further alarm her. It worked well. The hole for the valve was found with the cylinder cap removed and the extension of the indicator inside the open cylinder. The cap was then put back in place and centre-drilled, drilled and tapped. The thread was tested by screwing in the valve. I am using an off-the-shelf check valve because work (hopefully) smarter not harder:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869931.jpg)

Nice solid connection.

However, just to keep things tight and pleasing, I wanted the internal end of the valve to be flush with the inside of the cylinder cap, so I counterbored the hole using the biggest endmill I have, to create a recess:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869954.jpg)

I was pleasantly surprised to find that my measurements were pretty decent:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869953.jpg)

And so, state of the art so far:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/869952.jpg)

It's starting to look like something - maybe not an engine yet, but at least a cylinder.

Now, another question for you guys: will this uniflow cylinder (about 36mm diameter) require drain cocks? And if so, where should they be positioned?

gary

Title: Re: A Simple Uniflow Engine
Post by: Jasonb on July 06, 2020, 07:02:24 AM
well it's quite a solid lump so will be prone to condensation, the drains can be used to remove that and also to allow steam to be blown through teh engine to warm the cylinder.

Ideally put the holes at the holes so they break into the bore as low down as possible, (can be drilled from the side if that suits) and as close to the ends as possible. But the steam is likely to carry condenste with it where ever the holes are places.
Title: Re: A Simple Uniflow Engine
Post by: simplyloco on July 06, 2020, 08:23:55 AM

Uniflow engines are not my game, but cylinder drain cocks are useful in preventing a hydraulic lock on startup.
John
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 06, 2020, 09:58:22 AM
Jason and John - thanks.

Drain cocks it is.

 :ThumbsUp: :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on July 06, 2020, 11:44:57 AM
Hi Gary, thinking in particular about the ďuniflowĒ engine layout, I have to agree with the recommendations for condensate drains.  But where to put them is an interesting question.

The exhaust is wide open when the piston is at the bottom centre, but of course it is closed when the piston approaches the top, to condensate has no where to go.  The valve cannot lift to open to the exhaust as with a slide valve engine.  And of course the inlet valve has steam pressure holding it closed, and further more it is not at the bottom for easy flow of condensate.

If the cylinder is horizontal, then at the bottom, but very close to the top head, so condensate outlet is facilitated by gravity as the piston approaches the top dead centre.  (Away from the crank shaft.)

If the cylinder is vertical, then the condensate drains should be at the top, near the head, but at any orientation that suits the rest of the arrangement.

Itís looking good so far.

MJM460
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 07, 2020, 04:33:31 PM
Hi, and thank you MJM.

The cylinder will be horizontal.

I have ordered two drain cocks today - Stuart Models type.

I reckon one should go as you and Jason have suggested, and the other just in front of where the face of the piston will be at bottom dead centre. They will both be on the same side of the cylinder and as low in the bore as I can get away with.

Is that a  reasonable plan?

gary
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 07, 2020, 10:56:54 PM
Returning to the crank webs: my previous efforts to make these in the lathe using the 4-jaw independent chuck were not successful. For reasons that I have not yet figured  out, the holes were out of parallel, which would have put the journal out of parallel with the main shaft. So I tried a different tack. I glued the two rough-cut pieces of steel for the webs together with superglue (as on page 4 of this thread), and squared them off in the mill. The holes were then drilled and reamed with the two webs glued together. At one point the heat generated by the drilling destroyed the superglue and the webs came apart but I managed to rescue that and glue them back together again.

Next - with them still glued together - I rounded the corners with a corner-rounding endmill...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870114.jpg)

... after which - with them still glued together - I tidied the milled corners up a bit with a file...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870113.jpg)

... before using a small blowlamp to break the superglue bond and separate the webs. You know when the glue is about to give when it starts to smoke, and believe me you do not want to be breathing that smoke. There is still a bit of filing and polishing to do on the webs, but mission accomplished - the holes are all parallel and the webs sit nice and square on what will be the shaft and journal:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870112.jpg)

And here is the story so far:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870115.jpg)

Thanks for all your help and advice to date...

gary



Title: Re: A Simple Uniflow Engine
Post by: simplyloco on July 07, 2020, 11:43:58 PM
I look forward to seeing this run!
John
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 07, 2020, 11:49:25 PM
Thanks John.

So do I, even though it will be a while.

My main anxiety at this point is about whether or not these two flywheels are big and heavy enough.

There's only one way to find out though...
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on July 08, 2020, 01:14:21 PM
Hi Gary, crankshaft looks like you solved the problem.

With the drain cocks, the issue is that the condensed water is virtually not compressible, so when the piston approaches the top head, very large forces are created in bringing everything to a very sudden halt if there is no where for the condensate to go, and of course, gravity has already made sure it is on the bottom, so that is the best place for the drain valve.

At the Botton centre, I am not sure that the drain is really necessary, as the piston does not trap the condensate at that end.  In part it depends on where the exhaust port is, usually on the bottom with a horizontal cylinder, so any condensate goes out with the exhaust steam.  Otherwise any condensate formed when the engine is running can be a problem.  And you donít normally leave the condensate drains open once the engine has warmed up and is running.

I canít really see any reason not to put a drain at the bottom, I am just not sure what it will achieve.  I would save the extra valve for the next project.  If the exhaust is actually at the top, even a small port at the bottom, piped into your separator, will do the job as an auxiliary exhaust, and do no harm as it is closed off by the piston once it is on the way back to the top.  A peculiarity of the uniflow design.

MJM460

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 08, 2020, 10:27:23 PM
Thanks MJM - you have given me food for  thought regarding the cylinder drain cocks and the exhaust. I may come back to you on that for further advice when I get back to working on the cylinder.

Meanwhile, a little bit of progress with the crankshaft this evening. The webs were given a further clean up using my cheapo Dremel copy with a small flap wheel. There is still some way to go to make them look really nice but that can be done once the crankshaft is finished.

I decided to use the Loctite and pins approach given that this is my first proper crankshaft. In the photo below, the journal has been fixed into the webs with 638. The actual shaft is still loose and is just in situ to keep everything in line:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870213.jpg)

Tomorrow night I'll Loctite the shaft in and all being well will do the pins at the weekend.

Maybe my next crankshaft will be silver soldered...  :)
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 12, 2020, 10:26:45 AM
Time for another bit of state-of-the-art CAD:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870414.jpg)

It's a peculiarity of mine that I prefer to express metric measurements in centimetres rather than millimetres.

This is an actual size drawing of the cylinder based on the original plans by Stan Bray scaled up to x3.5, along with the piston. Note the length of the piston, which removes the need for a piston rod and crosshead guide. This is taken from the plans. Because nature is notoriously reluctant to be scaled, I am a little concerned that the much greater mass of this piston (in the original the diameter is only 10mm)  could make it difficult to drive. I initally considered modifying the design with a shorter piston, piston rod, crosshead and guide, but have decided to stick with the plans as it is one of the characteristics of the design. Having never made a crosshead guide etc. before, I would have liked the challenge, but there will be plenty of opportunities for that in the future.

Should the weight of the piston turn out to be a problem I'll just have to modify it, either as above or perhaps by making it hollow. But to be honest I can't really see it being a problem, as this engine will run on a really good boiler. More of which in due course...  ;)
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 12, 2020, 10:20:24 PM
Pinning the crankshaft. Being a novice I needed guidance, and found it in a youtube video by Keith Appleton. The photos below don't need much in the way of comment:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870503.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870502.jpg)

I drilled the holes with some trepidation for fear that the bit would wander when it hit the silver steel bar...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870505.jpg)

... no problem though. Four good holes:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870504.jpg)

Matching various diameters of thin silver steel with various small drill bits left me only one option. Fortunately I had just enough of this diameter to make four pins...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870508.jpg)

... at which point a slight annoyance occurred. I had tested the drill and silver steel rod on a piece of scrap steel and the result was a pin that was satisyingly tight and had to be tapped in with a hammer (as recommended by Keith Appleton). However, in making the actual crankshaft I 'pecked' with the drill to clear swarf. This enlarged the hole a small amount and as a result the pins were much less tight in the holes - not rattling, but a sliding fit. However, I poured plenty of Loctite into the holes before pushing in the pins. I suspect it will be ok. If it isn't, it will just have to be fixed later. The crankshaft in progress will now be left for a couple of days to let the Loctite harden properly.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870507.jpg)

I then made a start on the piston. All I have to cut cast iron with is a small angle grinder, and this made such a rough cut that when I tried to face the end of the bar the tool kept catching and pulling the bar out of true. Fixed steady to the rescue! First time I have used it in ages:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870506.jpg)

It did the trick, and I faced both ends of the bar and spotted them with a centre drill, then removed the fixed steady, put the live centre in the tailstock and began turning the bar down towards diameter before calling it a night.

gary





Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 14, 2020, 11:25:37 PM
The redundant part of shaft between the crank webs was cut away, and the protruding ends of the remaining shaft and the ends of the pins were filed flat. This gives me something which bears some resemblance to a crankshaft:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870745.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870744.jpg)

I hope it runs true! Haven't tested it for that in the lathe yet...

It still needs a bit of shaping, tidying up and polishing, for which this toy - ordered a couple of days ago and still to arrive - should prove invaluable:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870742.jpg)

30mm belt, variable speed. Looks good to me, but another thing to find space for. Space that I don't have.

I then switched back to the piston. An indexable round-tipped carbide tool seems to create the best finish on the cast iron. I am creeping down to diameter taking very fine cuts with it, alternating with a piece of wet and dry paper wrapped around a square block of wood moving evenly back and forth across the surface, and using the cylinder as a gauge:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870743.jpg)

Nerve-racking stuff, for fear of overshooting. It's almost there, but the hour was late so I decided to call it a night and leave the final diameter to another day...
Title: Re: A Simple Uniflow Engine
Post by: Johnmcc69 on July 15, 2020, 02:02:56 AM
 :ThumbsUp:
 Nice work Gary!
 No rush, take your time, it's all coming together nicely!
 :popcorn:
 John
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 15, 2020, 08:20:15 AM
Thanks for your positive words John.

I have often been inclined  to rush things, but this pastime is teaching me to take my time...
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 15, 2020, 10:27:32 PM
I have often been inclined  to rush things, but this pastime is teaching me to take my time...

Argh. I should have sufficient self knowledge by now to be aware that when I say something like that I am tempting providence.

The piston makes a nice sliding fit in the bore, and pulls a good vacuum with steam oil. And I'm pleased with that radius at the shoulder, which wasn't in the original plans:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870787.jpg)

However, as we see more of the piston, machining marks become apparent...

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870785.jpg)

... and the more of the piston we see, the more apparent the marks become (and in the next photo they are actually more apparent than they are when the piston itself is inspected)....

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870786.jpg)

... until we look at the top, say, quarter of the piston and the marks become less apparent again:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/870784.jpg)

I did exactly what John counselled me not to do: I failed to take my time. The piston is now a good fit, but I came too close to overshooting with the tool and it left me with machining marks along the bottom 3/4 of the piston which - if I were to polish out - would probably leave me with the piston too loose in the cylinder. For all I know, the machining marks may not make a difference in functional terms, and the engine may run fine as is. However, at bottom dead centre quite a length of this piston will be visible and it will pain me to see those marks.

I have a few different ideas for possible fixes for this, ranging from leaving it alone through various other options to making a whole new piston. I won't go into these here because I'm going to live with this for now to see what emerges when I eventually run the engine with it in situ before making any modifications. If you have any ideas yourself, please feel free to post them and I'll let you know whether or not they are the same as mine. Remember that as it is this is a long piston which obviates the need for a piston rod, and the connecting rod joins to a hole drilled through the boss at the back end of the piston.

However, there is another isssue: I centre-drilled a small hole in the back end of the piston so that the tailstock centre would hold it true while I turned the piston. This hole may be a bit too deep to the point that it may well encroach on the hole for the wrist pin. I could get round this by - as per plans - milling a slot down the centre of the boss at the back end of the piston to effectively create a fork on the end of the piston which would be drilled through for the wrist pin. The too-deep centre-drilled hole would become history that way. But I really like the idea of having the fork on the connecting rod and a single flatted projection on the back of the piston sitting between the two 'prongs' of the connecting rod fork. In this latter scenario the centre-drilled hole may make mischief with the bearing, unless I shorten the whole thing a bit which I may do but I would prefer not to mess with the original proportions. .

If you get my drift...

Will evaluate both of these issues when deciding whether or not to try to salvage this piston or make a new one.

Suggestions welcome...



Title: Re: A Simple Uniflow Engine
Post by: Jasonb on July 16, 2020, 07:06:43 AM
If you do make a new one don't use that round insert tool as they will tend to get pushed off the work trying to take fine cuts or risk chatter on heavier ones (your marks look like chatter) Either switch to sharp HSS or a **GT insert with 0.2 or 0.4 tip rasius for the last millimeter.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 16, 2020, 08:14:52 AM
I found the round tool was fine on the deeper cuts but it did start to chatter on the final fine ones.

Advice noted, though! Will try what you suggest.

 :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 20, 2020, 09:45:27 AM
I almost wish this chatter-marked piston wasn't such a good fit in the cylinder bore so I wouldn't be in a dilemma over whether to keep it, modify it or make a new one!

However, I have decided to press on with it for the time being rather than end up chasing my tail. Decisions on what to do about it will be made later in the build. To be honest, the photos make the marks look worse than they actually are, even though they do remain an issue.

Here, a flat is being milled for the 'crosshead' hole. I used the rotary table with dividing plate and its tailstock as an easy way of flipping the part 180 degrees to ensure parallelism of the two flats:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/871242.jpg)

Both sides done. A light touch with the new belt sander (when it arrives) will tidy things up, but overall I am pleased with this bit:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/871241.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/871240.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/871239.jpg)

Then - after marking out the distance from the top end of the piston to the centre of the hole using a height gauge on the surface plate, back into the mill setup to find the centre in the lateral orientation:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/871238.jpg)

I did also get the hole drilled and reamed but my camera ran out of battery so more to follow...
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on July 20, 2020, 12:49:19 PM
Hi Gary, more good progress.

Personally, I would not worry about those chatter marks if you are happy with the fit.  There is just a possibility that they will carry a little oil and help with lubrication and sealing of the cylinder.  A bit of a wild guess, but interesting things happen on that scale.   Keep with it until you find a problem.

When it is all complete and working, if you still want to, that is the time to consider making a second one.  My little cylinders seem to work quite well with just a good fit, and a couple of ring grooves which, rightly or wrongly, I consider as labyrinth grooves which help reduce the steam bypassing the piston.  Your marks are a much finer scale, where different hydrodynamic issues rule.  All interesting learning.

MJM460


Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 20, 2020, 12:57:47 PM
Thanks MJM.

Pretty much how I see it too. I'm sure the piston will work fine as is so it would be disheartening to get bogged down with it at this point.

It had also occurred to me that the marks may help carry some oil.

The thing that annoys me is that with this long piston (which removes the need for a crosshead and guide) some of the marks will be visible at all but top dead centre.

But never mind - as you say I'll come back to it at the end and if all works fine and the marks still bug me I can always make a new one at that point, or possibly modify this one.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on July 26, 2020, 12:40:33 AM
Have been painting the exterior of the house all week, so progress has been slow for the past few days.

Fortunately it rained today. Returning to the main bearings, which are made of bronze:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/871862.jpg)

A rough trial assembly of the crankshaft with flywheels, pulleys, collars and bearings in situ:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/871861.jpg)

A close-up of one of the bearings in incomplete state:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/871860.jpg)

The part on the left is the bearing itself, drilled and reamed to a nice sliding fit on the shaft. It has two diameters - the flange at left, and the main part of the bearing adjoining it. This narrower part will pass through the frame of the engine and then through the retaining collar as you can see here. A circle of small screws will pass through the flange, the frame and part way through the retaining collar, holding the bearing in position in the frame. The surplus length of bearing (just to the left of the cast iron collar) will be turned flush with the bearing retaining collar once I have gauged the final size using a piece of frame material between the flange and the retaining collar as a guide. The bearing at the other end of the crankshaft will be a mirror image of this one, and the frame will also be symmetrical.

Finally, I decided today that the connecting rod will be a composite structure. The main length of rod will be 12mm EN8 steel, but - like the big end - the crosshead end (including the fork) will be of cast iron. The components will be joined together with M12 threads and Loctite thread seal. The picture below shows that a start has been made on the crosshead end and that there is still quite a way to go with this part. The fork has to be milled and drilled and the whole part will need considerable shaping to make it look leaner and more elegant:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/871859.jpg)

In the lathe chuck the steel rod awaits a corresponding thread to connect it to the crosshead.

Weather due to improve tomorrow, so it's looking like I'll be back on painting duty again...  >:(



Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on August 17, 2020, 12:26:24 AM
 It has been a while.

Spent the last few weeks painting the outside of the front of the house, waterproofing a section of flat roof, going on a campervan staycation and doing an exotic post-steampunk makeover on our bedroom:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873697.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873696.jpg)

Oh - and working.

Finally got back into the shop this weekend though. Made a start on the connecting rod and crosshead.The rod part is bronze; the crosshead and big end will be cast iron:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873694.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873695.jpg)

The whole thing will end up much slimmer and will hopefully be given some reasonably elegant shaping. The bronze section will be quite short as the whole assembly from hole to hole is only 16cm. Remember this engine has no piston rod, just an extended piston.

I paused there and swapped jobs to avoid having to do too much changing of setups in the mill.

The new belt sander has arrived:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873693.jpg)

It's much smaller than I imagined it would be. This is a mixed blessing because I have very little room to spare in my shop but was still able to find a bit of bench space to fix it to. On the other hand the limited capacity means that there are things you can't do with it. It's a neat little tool - variable speed. I got it on Amazon and when it arrived the power unit was lifeless. I contacted the suppliers and they replaced it in double-quick time all the way from China and as compensation for having sent me something that didn't work they also gave me an extra set of belts and a refund of £30 of the cost of the machine! The belt sander enabled me to get the crankshaft to this point:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873700.jpg)

By no means perfect but starting to look reasonable. I'll leave the final cleanup till the end of the build.

Small flats were then milled on the crankshaft - one for each component that will  be mounted on it:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873702.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873699.jpg)

I used the dividing setup to rotate the shaft 180 degrees after milling each flat so that alternate flats would be on opposite sides of the shaft. I was thinking about strength and the avoidance of warping the shaft by not having all the flats on one side, but I suspect it wouldn't have been an issue really. The flats are only 0.5 mm deep. The flywheels, pulleys and collars are held in place by stainless steel grub screws which are supplied with flat ends which will of course bear against the flats on the shaft, providing a nice positive drive. This took me to this point (though here the grub screws arent tightened and the components aren't aligned:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873698.jpg)

Looks not bad, but then I chucked it up in the lathe using an ER32 collet chuck to see how true it would run:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/873701.jpg)

Visually everything is fine apart from one of the flywheels, which has a distinct wobble of about 0.5 mm or maybe even a bit  more. Damn!

I'm pretty sure the problem lies in the flywheel itself. If I can I''ll true it up in situ on the shaft, and it's all set up ready to go tomorrow. However, I suspect it will ring like a bell and make pretty patterns in the brass, especially as I'll need to work at the tailstock end for one side of the pulley. If that happens I may take it off and turn it on a short mandrel,  but then it may still not run true when it's back on the shaft again and still require to be finished in situ. The other thing about this that's bothering me is that this will not only shave thickness off the offending flywheel, but also off the other one so that they are in balance with each other. The weight of these flywheels concerns me even as they are, as they seem pretty light relative to the long cast iron piston. Ultimately if they prove to be too light I'll either have to modify them somehow or make new, bigger ones. I'd definitely prefer not to have to do either of these things, though...



Title: Re: A Simple Uniflow Engine
Post by: crueby on August 17, 2020, 12:50:05 AM
Nice progress Gary!  For the wobble on the flywheel, one thing you could try is to put two more grub screws in, so that they are spaced evenly 120 degrees apart. That way you can tighten/loosen them to take up any play on the shaft, which is likely the source of the problem - a tiny bit of play at the hub magnifies out to a noticeable wobble at the rim. When it will fit in the space available, I've switched to using a taper-lock setup on all my flywheels, runs much truer and is still removeable - just showed that over on the Mann truck thread. May not be room for that on your engine, so the other grub screws would do the same job. You would not need more flats on the shaft, the one is fine to give it grip, the others are just for alignment. A little Loctite Blue on final assembly will keep everything in place but still allow removal if need be.

Oh, and watch how much you drink before bed, you might get nightmares of being caught in a giant machine with that paint job!   :LittleDevil:
 :cheers:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on August 17, 2020, 01:02:54 AM
Or maybe drink more to suppress the terror of it...?   :wine1: :wine1: :wine1:  ;)

No, tbh we spent quite a long time on marking out that big purple gear and its geometry has a surprisingly calming effect.  8)

Great idea with the extra grub screws Chris. Definitely worth a try, especially if it lets me avoid whittling down those flywheels. Will give it a try.

Was planning to look at your thread in a minute anyway, so will do so. I'm interested to see your taper-lock flywheels.

Cheers!

 :cheers:
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on August 17, 2020, 01:34:17 PM
Hi Gary, more good progress.  I would not worry too much about the flywheels being too light, it is very difficult to get a feel for how much rotational inertia is required for an engine, so I would always recommend trying it out before you decide on whether they are adequate.

Remember that flywheels are inherently balanced unless you go out of your way to give them some unbalance.  Certainly the piston mass will be the main cause of engine unbalance, but that has to be compensated for partly by adding weights, usually on the crank webs opposite the crank pin (not in line with it).  Even that only balances the forces due to the crank and big end being off the centreline.  Balancing the reciprocating mass of the piston requires a more complex arrangement.  The more important issue for this engine is the flywheel inertia required store enough energy to drive the piston over top dead centre against the incoming steam, once the peg opens the inlet valve, as the piston will still be moving towards the top dead centre, unlike your oscillating engines or a slide valve engine, where the valves normally do not open until the piston reaches top dead centre.  If the flywheels are inadequate itís slowest running speed might be quite high. Adding some mass to the rims might allow it to run a bit slower if necessary.   But again, now they are made, apart from thinking about truing them up, wait until you have the engine running to see what it will do.

Did you ream the bores of the flywheels?  Have you investigated to see if the bore is really out of line or just a bit loose?

That sander looks like a handy item, and the seller obviously treated you well.  Worth remembering for when you next need something.

MJM460

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on August 17, 2020, 11:43:22 PM
An evening of fretting, pondering and measuring as the inevitable mid-build crisis intensifies.

@Chris - I really hoped that your diagnosis was correct, but in this case I do not think it was. Everything runs reasonably true on that shaft apart from the flywheel in question. I loosened it and spun it on an unflatted part of the shaft - still the wobble. I swapped the two flywheels over - still the wobble on that same wheel. There is a very slight wobble on some of the other parts, including the other flywheel, but it is almost liveable with and will probably be fixable either by your three-screw method or a very minor skimming, or both. But the wobble on the wobbly wheel is in another league.

@MJM - the bore of the flywheels were indeed reamed and they make a nice sliding (almost piston and cylinder-like) fit on the shaft. I took the offending flywheel off and went on a measuring spree with the surface plate, height gauge and micrometer. The bore appears to be concentric with the outside of the central boss, but the outer parts of the wheel are out of true. The micrometer showed me that there is a variation in thickness of about a maximum of 0.4 mm around the wheel. That, I think, is what I'm seeing when I spin the shaft in the lathe.

I originally turned the flywheel+boss assemblies on a superglue arbour held in the ER-32 collet chuck, both sides in one setting. That should have left them true and of even thickness. However, I used the wrong tool and got a poor surface finish. Following advice on the forum here I put them back in the lathe and gave them a finishing cut on each side. I can't remember how I held them for this, but it's possible that I got sloppy and just put them in the three jaw and turned them over after finishing each side. I can think of no other reason why there would be variations in thickness at different points round this flywheel. If so, maybe I just got lucky with the other one.

I reckon the easiest fix will be to set up another superglue arbour and re-face the wheel both sides in one setting. If it ends up looking thinner than the good wheel, then the good wheel will get the same treatment. In theory (ha!) they should both run true after that. Any minor wobble at that point could - I guess - be rectified by the three-screw treatment.

I also have to confess that there is a very small visible runout in the crankshaft itself. I don't think that this is wholly due to runout in the lathe spindle. I trued up the lathe as best I could before beginning this build and it's not perfect but probably as good as can be expected from a standard import machine which is a few years old. But I did obsess over the lengths of silver steel bar that I bought to make the shaft with  and it seemed to me that none of them were perfectly straight. I didn't see any point in ordering more that would be the same, so I just used the best ones. We're not talking major runout here, but it is just visible in the lathe even with the tailstock centre holding it. However, in the finished engine the shaft will be held by a fairly robust bearing at each end and I'm guessing that this will stabilise it. I'll make a new crankshaft if  have to, but I think the inaccuracy is minor enough to get away with. We shall see...

Re-machining that flywheel will be starting point, at the very least.

@MJM - absolutely. I have no clue how this engine will perform or whether the flywheels will be adequate. I certainly won't be making any changes to them until I have seen it under air or steam. Preferably the latter!

Thank you both for your input. Even more so if you have read this lengthy post! If you think I'm missing something, please let me know...

 :ThumbsUp: :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on August 18, 2020, 08:43:07 AM
On reflection - apologies for the length of the above post. This is pretty routine stuff really, and hopefully easily rectifiable. Hardly a 'crisis'! Have decided to true up the wobbly pulley not on a superglue arbour but fixed with the grub screw on a short arbour with a flat to mimic the shaft. Any residual wobble on it or any of the other components on the shaft can then be given a final truing up in situ.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on August 24, 2020, 12:20:20 AM
I trued up the wonky flywheel on a short mandrel milled with a flat to mimic the crankshaft.This helped a great deal and brought it to the condition that one would expect from a new flywheel before final truing up. The other flywheel was also skimmed to keep them the same size. Not a huge amount of metal needed to be removed, though it remains to be seen later in the build whether the two flywheels are heavy enough.

I then followed Chris' advice and made two extra holes in the bosses of both flywheels and pulleys. Blithely ignoring the wisdom of generations of engineers I did not drill the holes at an angle and consequently had to use my small Bahco adjustable spanner as a tap wrench due to lack of room for anything else. It went ok though. Keith Appleton would be proud of me.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/874274.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/874273.jpg)

For some reason I got mixed up and drilled and tapped the extra holes in the pulleys M5 instead of M6, but no  matter - I'll get some M5 grub screws and do the final truing up with them when the crankshaft is mounted in the frame. I also put a crown on the second pulley.

Truth to tell, there is a very slight but visible runout on the crankshaft. As noted previously, it may have been there in the silver steel bar from the start. Or perhaps in my lathe. I'm reasonably hopeful that the frame and bearings will accomodate this. If they don't, I'll make a new crankshaft - but fingers crossed...

With the crankshaft pretty much done for now, I went back to the connecting rod to set up for milling a slot to create the crosshead fork which will accomodate and articulate with the tab on the end of the piston. The tab on the piston is 9mm wide so figuring that an endmill will cut a little wider than its actual diameter I'm starting with an 8.5 for the slot but will swap this for a 9 if the slot isn't wide enough. You can always take away more but you can't put it back.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/874272.jpg)

This is not workholding at its finest, but I couldn't think of a better way to do it with the gear that I have. Still, it's cast iron and quite easy to machine so I'm hopeful that if I take light cuts with high cutter speed it won't move in the chuck. The fork will be radically slimmed down and shaped but I'm leaving that until it's functional for ease of workholding.

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on August 30, 2020, 11:43:53 PM
A reasonably good session this evening.

The chuck on the rotary table held the part perfectly firmly and allowed me to mill the slot for the fork without any movement:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/874892.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/874891.jpg)

Of course some metal has to be removed from both parts to allow the crosshead to articulate. I started with the 'tab' (don't know what else to call it) on the end of the piston:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/874890.jpg)

As you can see I used my 'one size fits all' corner-rounding endmill for this, so called because it's the only one I have. Every rounded corner on this engine will have the same radius!

It turned out not too badly:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/874895.jpg)

Should be fine with a minimal amount of tidying with a file or the belt sander.

It was then time to cross-drill the fork. I used my new electronic edge finder and the DRO to find the centre of the part:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/874894.jpg)

If you don't have an electronic edge finder, you want one. You really do. As soon as the sprung ball at the bottom of the probe touches the metal, the thing beeps and the red LED lights up. Way better than peering at a conventional finder...

The cross-hole was drilled and reamed 8mm to match the hole in the piston tab. Here you can see the piston temporarily connected to the fork with a bolt and dome nut:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/874893.jpg)

In due course I'll turn a bronze pin. There is still quite a bit of shaping to do on that fork, not least milling off those corners which are still preventing the joint from articulating adequately. After that it will be shaped for aesthetic reasons, as will the bronze connecting rod.

There is a small amount of lateral play between the cylinder tab and the fork. I suspect it doesn't matter, but if it does I can always widen the slot a bit and shim it with bronze washers. Hope not to have to do that though...

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 01, 2020, 11:22:19 PM
In order to allow sufficient travel, the corners of the crosshead fork were milled away using - you guessed it - my solitary corner-rounding endmill, which I have to say is a surprisingly versatile tool given that it only does one thing (does that make sense?!).

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/875091.jpg)

This still doesn't enable it to swing all the way round, but not an issue as it allows for an arc that is way wider than it needs to be to take the stroke.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/875090.jpg)

The crosshead is now functional though it needs a proper pin and it still has to be shaped and tidied up in the interests of elegance. However, before I do the latter I'm going to move on and start on the big end, which I suspect will be the trickiest component of the build.
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on September 02, 2020, 02:56:12 AM
Hi Gary,

More good progress.  Glad to hear the rounding over cutter is working well.  Much better to have one item that does its job well than several that do a bit of everything but all badly.

MJM460
Title: Re: A Simple Uniflow Engine
Post by: crueby on September 02, 2020, 03:26:35 AM
Very good! Watching along with the elves and popcorn...   :popcorn:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 02, 2020, 08:36:55 AM
Many thanks guys.

It's great to have your encouragement, which - combined with a sprinkling of magic dust from Chris' elves - will help me through this build...

 :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 06, 2020, 11:53:09 PM
Started on the big end.

Slow progress as there's always too many other things that need to be done, the result being a not-very-exciting post here.

Two pieces of square cast iron bar:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/875461.jpg)

Unfortunately I have no room for a bandsaw so the best tool I have for cutting this kind of stock is a humble angle grinder, which results in such a rough cut that I have to spend a fair bit of time facing the blanks. I cut the small piece first, then realised that it wasn't big enough so I cut a piece off the larger bar and decided to put it down to experience. However, it occurred to me that if I use the smaller piece to make the cap for the big end bearing it will save me from having to cut the bearing with a slitting saw. So, using my cheap bangood facemill (which seems to work fine) I am in the middle of milling the blanks to so that they more or less match each other as a starting point. There's quite a lot of iron there so it will take a fair bit of machining to get the big end to the desired final size and shape.

As you will know, while cast iron is easy to machine it is a grimy old process. The swarf gets everythere and it is a pain to clean up.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/875460.jpg)

Ah well... it's a wonderful metal nonetheless.

One step at a time...
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 16, 2020, 11:15:27 PM
So...

...the two pieces of cast iron were milled to roughly the size and shape of generous blanks for the big end and bearing cap. Then two 6mm holes were drilled through the cap and counterbored. These were used to spot the locations through on to the main part of the big end, which was then drilled and tapped M6. The two parts were then fixed together with shortened M6 cap head screws and the assembly was put back in the mill and squared up:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876150.jpg)

The hole for the bearing was then drilled and reamed to 12mm:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876149.jpg)

This looks not bad, though the assembly is still massive and there is a lot of cast iron yet to be removed. Potentially more seriously, though - there is a very slight runout in that main hole. It may have happened because I forgot to lock the z axis of the mill before I drilled the hole, though I'm not sure. It is miniscule, and my instinct tells me that I'll get away with it, but I'm not experienced enough yet to have a sense of what the tolerances are and it is a pretty intergral component (well, aren't they all?!).

If it does turn out to be a problem, I wonder if putting a spring washer in each of the cap counterbores would give the bearing a bit of adjustability and wiggle room while everything beds in during the first few runs of the engine. Any thoughts on this would be most welcome, as would any alternative tips as I'd rather not have to remake the big end.

Overall, though, I am daring to hope that the runout is too slight to be an issue over the short length of the crank journal.

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 17, 2020, 11:24:16 PM
The connecting rod will screw into a hole at the bottom of the big end. This evening I drilled and tapped the hole. The big end was held in the milling vice and centred in both axes using the DRO. This mill is quite small and doesn't have the capacity for a piloted spindle held in the drill chuck with workpieces over a certain (and not very great) height, so I put the first tap straight into the drill chuck and used 'tapping mode' to start the thread. Most of you will know this function on some of these import mills, but if you don't, there's a green button on the end of each arm of the downfeed handle which changes the chuck direction with a single press when tapping mode is activated so you can withdraw the tap every few revolutions to clear the chips. It's pretty handy:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876214.jpg)

State of that mill but I see no point in cleaning it all up when I'm going to be milling more cast iron over the next few sessions.

Unfortunately in this particular instance tapping mode didn't work very well as the tap kept turning in the chuck, but it did manage enough threads to give me a perpendicular start, after which I was able to hand tap it in the bench vice without worrying about an off-centre thread. No big deal; a routine operation, but hey - I like pictures  :) :

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876213.jpg)

All good - looks nice and straight when the blank for the connecting rod is screwed in. Still loads of swarf to make getting that big end down to a reasonable size and shape though:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876217.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876216.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876215.jpg)

Cheers,

gary
Title: Re: A Simple Uniflow Engine
Post by: propforward on September 20, 2020, 12:40:39 PM
Hi Gary,

Some excellent work here as always. I think you are very critical of your own work. Itís all looking like great progress to me. Is that piston made from a cast iron bar, or is that steel?
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 20, 2020, 01:11:40 PM
Thanks Stuart - very kind of you.

It's cast iron, as are the cylinder, the crosshead and the big end.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 21, 2020, 11:25:24 PM
There will be a spigot protruding from each side of the big end, the faces of which will run against the crank webs. The lines scribed on the assembly in the photo below are set apart at a distance which is a little bit wider than the final overall width of the big end from the face of one spigot to that of the other:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876506.jpg)

I milled down to these lines with the face mill, then again with the height gauge and surface plate marked out the final width of the big end minus the length of the spigots. You can probably just about make out these two new lines in the photo below. The assembly was transferred to the independent 4-jaw chuck in the lathe. A short length of 12mm silver steel bar was held in the tailstock chuck and pushed through the split bearing in order to help with centring, to lend rigidity to the setup and to test whether or not the miniscule degree of runout in the bearing hole (discussed a few posts back) was likely to cause problems. I'm pleased to report that as far as I can now ascertain the amount of runout over the short length in question is insignificant.

A turning operation was then embarked upon to narrow down the body of the big end while leaving the spigot on each side standing proud of the face:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876505.jpg)

I'm using a circular carbide tool to leave a radius where the spigot will meet the face. This should look good but it will also be stronger than would a ninety degree angle, as per a suggestion from Jason further back in this thread.

This turning operation is not one to rush, what with the unbalanced weight of cast iron spinning in the chuck, so it is taking a while to do, over several sessions...


Title: Re: A Simple Uniflow Engine
Post by: propforward on September 22, 2020, 06:47:01 PM
Nice. Looks like a solid approach - excellent finishes too.

I suppose you could have opted for a faceplate mounting, then added some balance weight if you had really need to go with higher rpm's, but this set up looks like it worked out really well for you. Easier than setting up on  a face plate for a start.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 22, 2020, 08:14:06 PM
Hi Stuart - yes, I did consider using the faceplate but on balance (no pun intended) I decided to just go with the 4-jaw. It's a slow job but there's no rush really. I'm away from home until Friday but hope to make a bit more progress over the weekend...
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 28, 2020, 12:09:38 AM
The main body of the big end in progress has now been more or less slimmed down to final width, though the 'spigots' projecting from the sides still need to be brought to final dimensions. After that there is still more work to be done on the overall shape of the part, both for weight reduction reasons and for looks:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/876999.jpg)
Title: Re: A Simple Uniflow Engine
Post by: crueby on September 28, 2020, 12:23:13 AM
Nicely done, coming along great!
Title: Re: A Simple Uniflow Engine
Post by: propforward on September 28, 2020, 01:17:09 AM
Nice work Gary!
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 28, 2020, 10:05:13 AM
Many thanks guys.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 28, 2020, 11:14:26 PM
In order to check that the two spigots were the same length, I clamped a couple of parallels on to the assembly and measured the gaps with the inside jaws of the calipers:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/877081.jpg)

The difference was negligible so I considered the part to be symmetrical. Measurement of the overall width told me that I needed to remove 3mm for the assembly to fit between the crank webs, so I took facing cuts with an endmill to reduce each side by 1.5mm. I will confess to you that I have a photo of this operation but the mill is so covered in cast iron swarf at this point that I'm ashamed to show it. I am, however, pretty pleased with the result, which is a smooth-running fit, snug but not tight:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/877080.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/877079.jpg)

I'm quite pleased with this, but you can see that even when I have reduced the size of the big end (which is the next step), the flywheels will still be quite small by comparison. As discussed somewhere above, I have no clue as to whether or not this will be a problem. The plan is to press on with the build and find out when I first test the engine on air. If I have to enlarge them I will do so.

Meanwhile - iron age digital compact camera?

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/877078.jpg)

There's a lot of cast iron yet to remove from the big end, and even these rounded corners may yet disappear with some closer machining to reduce the size. But still, progress...

Title: Re: A Simple Uniflow Engine
Post by: crueby on September 28, 2020, 11:37:06 PM

.......
Meanwhile - iron age digital compact camera?
(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/877078.jpg)

Mil-Spec iPhone! 
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 28, 2020, 11:40:50 PM
 :)
Title: Re: A Simple Uniflow Engine
Post by: propforward on September 29, 2020, 12:02:54 AM

.......
Meanwhile - iron age digital compact camera?
(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/877078.jpg)

Mil-Spec iPhone!


 :ROFL:   :lolb:

I literally LOLíd at that.  :facepalm2:
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on September 29, 2020, 12:07:36 AM
Hi Gary, more great progress.

The main effect of the size of that big end is on engine balance, and as I believe it will be a relatively high speed engine, a large unbalance will get exciting.  However, the big end mass can be balanced by weights added to either the crank webs or a smaller mass at the rim of the flywheels, and then it just adds to the moment of inertia of the flywheels.  If my memory serves me the maths says you balance the weight of the big end plus about one third of the connecting rod as a starting point.  You would divide this and put half each end of the crankshaft.

However, as you add your trademark wonderful artistic touches, it is worth considering detail that  reduces the remaining mass in your design. 

For my part, the best piece of material to use is one you already have, or can easily source, that is big enough and regular in shape so it is easy to hold while you drill and tap for the securing bolts and that all important bore.  Then you can make as much swarf as you fancy in trimming away the bits you donít need.

It appears that in doubling the original plan size, you have also doubled the bearing cap bolts and spacing.   As it is not a scale model, you probably could have got away with leaving some of those details a bit smaller, but that is an idea for the next engine, no need to change now.  I find that each successive engine, I am prepared to makes bolts a little smaller and clearances between features a little tighter, though having tried 2 mm bolts, I think further progress in that direction will be limited, and I prefer 2.5 mm and larger.  Not sure that I will ever get to 1 mm like others on this forum.  They show amazing skill that I can only admire.

MJM460
Title: Re: A Simple Uniflow Engine
Post by: steam guy willy on September 29, 2020, 02:20:55 AM
Hi Gary, Talking about nuts and bolts... here in The Uk we have EKP Supplies that make BA nuts and bolts with a smaller head size... This gives you a larger stronger thread with a more scale size bolt head,  these bolts go down to 10 BA with 12 BA heads. here is a small part from the catalogue !!

Willy
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on September 29, 2020, 08:26:24 AM
@ Stuart - glad you liked it. The viewfinder works fine but I'm now trying to figure out how to get it to take pictures.

@ SGW - thank you. I tend to work in metric and most of my tooling reflects that, but good to know nonetheless. All good info for future use.

@ MJM - on weight and balance: yes, I can imagine that if that big end were to be left as is the engine would be bouncing all over the place, and no great benefit in bolting it to the bench as it would probably take the bench with it. My plan at this stage is to carve away at the big end to lighten it as much as possible (hopefully in a way that looks good too), then see what I'm left with. Making the flywheels bigger and heavier will be a second step to be taken only if required.

Your point about scaling - yes, absolutely. This engine is 3.5 times the size of the original plans, and most of the main dimensions (bore, stroke, throw, combined mass of flywheels, etc) reflect that. In terms of finer details, though (e.g. the size and spacing of the screws for the big end cap) - it was pretty much guesswork. I am aware that I have a general tendency to over-engineer things, though, and you make a very good point about not needing to scale everything up. As you say, a learning point for next time...

Thanks all.

 :ThumbsUp: :ThumbsUp: :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 05, 2020, 10:56:50 PM
Slow but steady progress... and a disaster!

I roughed out the rest of the main form of the big end by drilling and milling, but decided to finish it the old-fashioned way - with files. It's taking shape, though there is still a way to go to get the shape right. It's still going to be quite hefty but it's smaller than it was:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/877797.jpg)

Work in progress.

But a very bad thing happened this weekend. I got an e-mail from one of the neighbours at my place in France to tell me that the huge gales they have been having there have removed one third of my workshop roof. He will cover the machines inside in plastic sheeting when the weather dries up but he can't climb over the wall so will have to wait till he receives the keys which I posted today. I'm keeping my fingers crossed that my builder friend who lives several hundred kilometres away in another part of France will be able to drive up and put on a new roof for me. However, he (rightly) can't do this straight away because his first grandchild is due to be born any time now! Ordinarily I would go over but due to covid there would be quarantine on my return for both me and my partner and we are both up to our eyeballs in work which can't be sidelined.

So basically I have to just swallow the fact that my lovely machines (some vintage in excellent condition) are going to be rained upon - possibly numerous times - before anything can be done about it. My neighbour took photos.

The exterior of the building, showing the missing roof section:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/877796.jpg)

The view down through the gap where the roof used to be:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/877795.jpg)


Utterly bleak.

 :disappointed:
Title: Re: A Simple Uniflow Engine
Post by: crueby on October 05, 2020, 11:23:54 PM
Oh no! I hope it can get protected well enough.  :(
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 05, 2020, 11:28:29 PM
Yes... thanks Chris.

My friend will hopefully be able to go there to put on a new roof in the not too distant future, but it all takes time and being the Autumn it will rain regularly before that happens.

And when it rains in France, it can really rain...
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on October 06, 2020, 12:23:30 AM
Sorry to hear about the workshop roof Gary.  Hopefully those keys will arrive, and the neighbour will be able to secure some waterproof sheets over the machines.  Thank goodness for good neighbours.  At least you have been alerted so can start making arrangements to get repairs started.

I wonder if it would be worth arranging for the neighbour to have some WD40 or Innox to spray over the machine surfaces when the keys arrive.  WD 40 might also be worthwhile in the electrical parts, but I expect others will also have good ideas to minimise the damage and what to inspect and do when you are at last able to return.

The big end is looking good.

MJM460

Title: Re: A Simple Uniflow Engine
Post by: propforward on October 06, 2020, 02:18:02 AM
Gary, I'm heartbroken to see this. I hope your neighbour can help you out. WD-40 is a good idea in my view - tarps and WD-40 will go a long way to help protect those machines.

Best of luck to you!
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 06, 2020, 08:40:47 AM
Thank you both for your empathy.

Indeed, WD40 is part of the plan. I'm hoping that if the rain abates for a few days my neighbour will drench the machines in WD40 then cover them in plastic sheets, pending (hopefully) the arrival of my builder friend to redo the roof. Once the new roof is on, the plastic can come off the machines to let everything breathe. No doubt there will be restoration work to do at some indeterminate point in the future.

One good thing is that before shutting the place down every Autumn I have liberally sprayed everything with WD40 as one of the last jobs before I leave, the last time being October 2019. Fingers crossed that will help a bit.

We put on the existing roof about 7 years ago. This time we'll have to find a way to make it stronger...
Title: Re: A Simple Uniflow Engine
Post by: Ramon on October 06, 2020, 11:27:16 AM
Gary - my sincere sympathy for this dreadful situation. I can't even begin to imagine what you must be feeling right now especially as you have to rely on others to do what I'm sure you would rather be doing yourself. Hopefully your friends will do you proud.

I do hope it will not be as bad as it could be and that you will be able to get it all back to order without too much lasting damage.

The best of luck with it all

Regards - Tug
Title: Re: A Simple Uniflow Engine
Post by: Jo on October 06, 2020, 11:47:28 AM
 :o Nasty.

It looks like asbestos roofing sheets - they normally last forever  :thinking: You have less battens under the sheets to secure the sheets to than I would have expected. A few more wouldn't hurt. I assume that is the corner for the prevailing wind. Might be worth doubling up on the fixings if that is so. 

It should be an easy fix for a builder to do, won't take long  :ThumbsUp: (once they arrive   ::) )

Jo
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 06, 2020, 04:55:05 PM
@ Tug - thank you. I sense your understanding. Fingers crossed...

@ Jo - it's not asbestos even though it looks like it. It's 'fibro-ciment', a non-toxic asbestos lookalike. My place is in a green belt type location (a tiny hamlet with 200-year old houses) and the planning laws are super-strict. When we went to replace the old broken asbestos roof about 7 years ago, they specified fibro-ciment as it looks identical to asbestos. You know, traditional quaint rustic asbestos...

The stupidity of bureacracy ...  :facepalm:

We dutifully put up the fibro-ciment, but the first time it rained it began to drip water. The damn stuff isn't even waterproof!!! So I had to coat it with several layers of some grey waterproofing stuff from a big drum.

Crazy! And now this...

We live and learn. This time there will be more woodwork and a more secure structure. And planning be damned, I won't be using fibro-ciment. Some of that square-cut corrugated aluminium like the stuff Stuart (Propforward) has on his workshop will be better. Don't want to have all this nonsense again...

Thanks both.

gary
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on October 07, 2020, 12:14:25 PM
Hi Gary, we used to use a lot of that fibro cement, possibly still do.  But it was found quite early on that it fails in a brittle manner, and there were several serious accidents from people walking on the roof and falling through.  The building regs were modified to require a steel mesh under the sheet so at least no one would fall through if it breaks.  Existing roofs had to have a fixed notice prohibiting walking on the roof.  Try as I will, I canít work out just what physical principles are involved in making the wind obey the notice.  I suppose it doesnít walk on the roof.  Perhaps thatís it.  Of course there are no easy solutions when these things are discovered after the materials have been extensively used.

I believe the other disadvantage of the stuff is that it shatters explosively when exposed to fire, so not great for fire protection either, so I am not sure it was ever a great step forward.  But I wouldnít go back to the asbestos sheet either.  If the heritage people really insist on fibro material, perhaps install a layer of the usual metal, then a ď cosmeticĒ layer of fibro on top as a compromise.  Interesting that you use aluminium, we tend to use galvanised steel, though these days various high tech paint coatings are replacing the gal.

I hope that it can all be fixed soon.

MJM460


Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 07, 2020, 03:53:50 PM
Thanks MJM.

Ah, so the horrible stuff has the same name in English, apart from that first 'e' which is an 'i' in French.

Brittle is the word, and the fact that water seeps right through it is just ridiculous! And maybe in France the wind does actually walk on the roof. It certainly seems that it did, before bad-temperedly throwing a third of the roof across my neighbour's garden. Fortunately it didn't hit anyone with it.

I think I might use the metal (you are right - it's steel, not Ali - I just revisited Stuart's workshop log thread) with the rectangular grooved profile, but good idea MJM - it can always be covered with something else if absolutely necessary. There is also another kind of corrugated fibrous material that feels and looks like a kind of hard (but slightly flexible) felt. I don't know what it's called, but I have seen it in dark green and maroon colours. That might be a good option too...

Just for the record, the machines in the most exposed position are:

A vintage flat belt French drill press with its companion bench grinder    :(  :( :(
A Centec 2A milling machine  (which was?) in excellent condition           :(  :(  :(  :(  :(
A Myford ML10 lathe (which was?) in practically mint condition              :(  :(  :(  :(
A rare Burke No 0 milling machine which I had previously restored        :(  :(  :(
A not very special mitre saw                                                               :(
A couple of vintage countershafts                                                        :(
A Lister D Stationary Engine                                                               :( :(

Also various bits of tooling (hopefully protected in the chests of drawers that they are in) and three old French anvils (which will probably survive the deluge).

But there is other gear in other parts of the shop which is also at risk from diagonal rain...

Thanks for listening, anyone who reads this. I feel better now. A bit...
Title: Re: A Simple Uniflow Engine
Post by: Bearcar1 on October 08, 2020, 04:12:48 AM
 :o :o :'( :'( :shrug:


Man, that would almost be worth having someone cut the door open, release the lock and enter. weld a patch back over the hole after covering your exquisite machines.


BC1
Jim
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 08, 2020, 07:59:00 AM
Hi Jim -

You are right, for sure. Suffice to say though that there are nuanced reasons in the area of 'village politics' which weigh against that. It's a fine balance, but given the machines will have already got wet and - hopefully - the keys will have arrived with my neighbour within a few more days, I have decided just to suffer it until they arrive. Also, when I last spoke to him the forecast was for rain and wind all this week, so he probably wouldn't have been able to cover the machines anyway.

I'm hoping that my builder friend will be able to go up in the not too distant future...

Thank you for your  interest!

gary
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 09, 2020, 11:40:43 PM
A bit of progress.

My neighbour in France has received the workshop keys. Very quick delivery by post. Kudos to the Post Office! He is going in to check out the state of play tomorrow morning and make a start on basic protection of the machines.

The weather there has picked up with a lovely sunny day today and a good forecast for tomorrow, so hopefully the machines will dry out, at least to some degree... it's the thought of water getting into all these bearings and slideways by capillary action that bothers me, but as my ever-optimistic other half reminds me, they are well lubricated.

My neighbour has been speaking to some other people we know who may be able to repair (or replace, hopefully) the roof sooner than my friend from down South would be able to...

Fingers crossed...

:insane:



Title: Re: A Simple Uniflow Engine
Post by: Bearcar1 on October 10, 2020, 04:14:33 PM
 :NotWorthy: Gary, my prayers are with you my friend.... damn, the thought of water damage to those machines makes me sick to death.    Best of luck and I hope all will be well.


BC1
Jim
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 11, 2020, 10:47:42 AM
Thank you Jim - that's very kind of you.

I know... it's a horrible thought and it will be on my mind until it's fixed and I can get over there to check them out. My neighbour has now been in and he sent more photos. The Myford ML10 seems to be the worst affected because it sits in the direction of the prevailing wind (which is Westerly, blowing in from the Atlantic and full of rain at this time of year). The lathe is wet, and now has surface rust on the slideways and chuck and goodness knows where else. I have asked my neighbour to go out and get loads of absorbent material such as rolls of paper towelling, a bunch of cans of WD-40 and plenty of plastic sheeting or tarpaulin. I am now waiting for an update from him.

Meanwhile, my builder friend (the original one) has committed to definitely going up to put on a new roof in the last week of this month, after his grandson is born. We are going to use corrugated iron - either the traditional kind (which would be galvanised) or the more modern box section type (pre-painted grey) - we haven't decided yet, but definitely NOT the dreaded 'fibro-ciment'! He is going to add more timber to the underlying structure, add some tie-down straps and use more fixings, and build a small parapet at the top of the wall to protect the edge of the roof from that prevailing wind (which was as high as 150 km/h at the time the roof section blew off). Hopefully that should do it! And hopefully my neigbbour's intervention will at least prevent things from getting worse until the new roof is on and the tarps can be taken off the machines, giving them a chance to dry out.

Cheers Jim, and the others of you who are being so supportive over this.

  :LittleAngel: :LittleAngel: :LittleAngel:
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on October 11, 2020, 01:21:58 PM
Hi Gary, itís good to hear that things are starting to move on the recovery front. 

With any luck, that visible rust will be superficial and relatively easy to polish off when you are able to get back.  The electrics are potentially more troublesome, but I will leave it to others to make more informed recommendations for what to think about there.  First thing is to get a roof on.

MJM460

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 11, 2020, 05:57:50 PM
Yes the electrics could well be an issue.  I'll probably not switch on any of the ones that have got wet until they have sat under the new roof for the whole (hopefully hot) Summer next year to give them a chance to dry out. If I do have to replace any motors it will be with 3-phase or treadmill type units with variable speed control, for sure.

Thank you...
Title: Re: A Simple Uniflow Engine
Post by: propforward on October 11, 2020, 08:13:29 PM
I am very glad to hear the keys got to your neighbour in a timely fashion, and I truly hope there is no damage.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 11, 2020, 11:04:05 PM
Many thanks for your supportive thoughts, Stuart.

Progress on the machine rescue front! My neighbour has been busy with WD-40 and the kind of plastic that is used to cover silage.

First, the Myford ML10:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878334.jpg)

Next, a cabinet containing various components (including a lovely old Brit indexing head with tailstock) and with a couple of countershafts on top:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878332.jpg)

And a vintage French drill press (L), a Centec 2A mill (C) and - half off camera -  a vintage American horizontal mill (R):

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878333.jpg)

There's a Lister D stationary engine in the foreground of that one that he hasn't covered yet but I have asked him to. The other machines are all in dry areas I think. All in all, that will suffice until my builder friend arrives in a couple of weeks to put on a new roof.

Now, on with other things...

I have been using two milling vices - one is a tilt and swivel job that is really too big for the small mill I have here at home. The other is a nice old British precision vice which - alas - I overtightened and damaged last week (I know... what a week...). It's fixable but I don't want to put time into it right now, so these two vices will go into my 'take to France' collection and find homes on the soon-to-be-dry machines I have over there. They have been replaced in my workshop here at home by these:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878342.jpg)

The little beauty on the left can be taken off its tilt and swivel mount and fixed straight on the milling table if desired. The t-slot table can be fixed to the mount. Very nice. The one on the right is quite hefty and it has 'angle lock clamping' to prevent jaw lift. It can also be used vertically as well as horizontally which will be very handy for e.g. slitting saw work. A bit of retail therapy to ease my mind following the roof disaster...

So, finally back to the engine with some significant progress today. The crosshead, connecting rod and big end are finished, bar a bit of final polishing and fettling:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878345.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878344.jpg)

The threaded sections of the bronze connecting rod show significant runout which is far greater than would be caused by normal 3-jaw chuck inaccuracy. It may be that the forces involved in cutting the threads with a die upset them. However, as the motion is linear I'm hoping to get away with it. The two washers are included as shims because I was inaccurate with the length of the non-threaded section of the connecting rod. I can play with this as I go along and if it still seems that they are needed I can either replace them with something that looks better or tidy them up. When it's all finalized, some Loctite threadlocker will be applied. All in all, I'm happy with it. Sure, it's chunky, but it will probably be a fast engine and my aim is to run it on a fairly large boiler.

Finally, the parts so far roughly assembled for demo purposes:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878347.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878341.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878346.jpg)

As I've said a number of times previously, my main concern at this point is whether or not those flywheels are big enough. Time will tell, but meanwhile next up (after a shop clean and tidy-up) is the frame. Going 3D at last...! 

 :cartwheel:




Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 12, 2020, 09:01:39 PM
My neighbour has been doing more work today, wrapping more items in plastic sheeting. This includes the Lister engine I mentioned yesterday.

This picture truly conveys how exposed the machines were:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878407.jpg)

Good temporary remedial work, though, and I'm counting down now until my friend can put a new roof on the shop...
Title: Re: A Simple Uniflow Engine
Post by: propforward on October 12, 2020, 09:02:59 PM
Phew - it is great to have great neighbours!

Loving the engine work Gary - really superb finishes on those parts, they look amazing!
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 12, 2020, 09:04:34 PM
You bet!

And good friends capable of re-roofing a workshop...

 :) :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 12, 2020, 09:05:57 PM

Loving the engine work Gary - really superb finishes on those parts, they look amazing!

Thanks Stuart - very kind of you.

I must admit it cheered me up to be able to assemble those parts like that.
Title: Re: A Simple Uniflow Engine
Post by: Johnmcc69 on October 12, 2020, 09:43:40 PM
Nice work Gary!
 Sorry to hear about the shop, at least maybe it was taken care of before more bad weather hits.

 Enjoying the build!  :popcorn:

 John
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 12, 2020, 09:59:44 PM
Thank you John.

There will inevitably be a fair bit of remedial work to do, but hopefully thanks to early intervention nothing will be irretrievably ruined. And - all being well - my shop will have a smart new roof which will be stronger than the one that blew off.

Glad you are enjoying the build efforts of a beginner like me.

 :ThumbsUp: gary
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on October 13, 2020, 12:07:29 PM
Hi Gary, good to see some protection in place.  At least no more should be able to get in now.

Good to see more progress on the engine.  I see what you mean about the flywheel appearance now they are lined up with the cylinder and control.  I am still inclined to see if it works, but it wonít be too difficult to make a separate rim and attach it if necessary.  A steel or better still, stainless steel rim, will make a nice two tone appearance. 

MJM460

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 13, 2020, 12:41:17 PM
Yes indeed, and bring on the new roof!

Agreed on the flywheels. I'll try running the engine with them as they are at first. I'll be starting on the frame very soon and will make sure that it's designed so that there's enough space around the flywheels to add steel rims if needs be. There's a small machine shop locally where the scrap bin often contains nice chunky steel discs (offcuts of large diameter bar) which would fit the bill nicely when bored to fit.

And yes - the two different metals would look good together.

We shall see if they are needed though ...
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 14, 2020, 10:18:10 PM
Way back on page 5 of this thread there was some conversation about surface treatments for iron and steel. John suggested that I try gun blue, so I ordered some at the time. It didn't arrive, I got a refund, and ordered some more last week. Better luck this time, so last night I tried it out on some spare bits of cast iron and a piece of silver steel:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878498.jpg)

That was without much effort at all - just a rough and ready degrease with some meths and then a quick application of the blue before rinsing off under the tap and finishing off with a wipe of oil. Very effective and easy to use, and with a little bit more work would bring up an amazing finish. However, I don't think it's the right look for this engine. I was hoping a light smear of it might bring a subtle blue hue to the metal, but it's grey through to black all the way, which to my eye would look a bit too severe for the cylinder, big end and crosshead of this engine. Instead, I'll do as Jason suggested, just applying a light smear of oil and letting the cast iron speak for itself. I'm glad I now know about the gun blue, though, and I do think it could look good for smaller accents such as screw heads, etc. And on other builds I know it can look great on major components too. A useful thing to have in the shop, I reckon.

No doubt many of you will know this, but for those who don't it appears to only work on ferrous metals. I tried it on aluminium and brass with zero effect.

To progress this engine further I'll need to at least make a start on the frame, and according to the idea I have in mind, the frame will require a base to be functional. The main base will be made from two massive pieces of oak that were originally intended for another (non-steam related) project that got sidelined. Joined together and shaped somewhat, these will create a very solid base which will hopefully create significant stability for the engine, which by all accounts could turn out to be something of a bucking bronco. Attached to this will be the two symmetrical sides of the frame made from the 5mm aluminium plate which you can see here. A piece of this plate will also be fixed to the wooden base horizontally under the engine. The two sides will be joined by a number of cross pieces which will act as bracing struts to give the whole structure rigidity.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878497.jpg)

That's the plan. Still quite a lot of work ahead...
Title: Re: A Simple Uniflow Engine
Post by: crueby on October 14, 2020, 11:13:34 PM
A few years ago I tried a few different blueing compounds on a variety of steels, worked good on some alloys, not on others. Tough to predict.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 14, 2020, 11:21:22 PM
What kind of alloys Chris?
Title: Re: A Simple Uniflow Engine
Post by: crueby on October 14, 2020, 11:25:46 PM
What kind of alloys Chris?
Tried it on cold rolled, drill rod, couple stainless, forget the details. Its back on a thread. Somewhere. Bottom line, needs experimenting like you did, as I recall there was no predictable results.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 14, 2020, 11:29:45 PM
Ah ok.

I found that the silver steel responded better than the cast iron did. Very dark, even colour with almost zero effort.

Certainly warrants further exploration in due course though.
Title: Re: A Simple Uniflow Engine
Post by: Kim on October 15, 2020, 05:52:57 AM
There are various chemical blackening agents designed for brass also.  I've used them on other projects.  They also have varying results.  I found that I got the most consistent results by doing a thorough fairly careful process (a good cleaning of washing, then rinsing in acetone, allowing them to dry thoroughly (without touching), then submerged in thinned brass black for a specific amount of time, followed quickly by a gentle water rinse and allowed to dry).  With that process I got pretty consistent results on the brass.  I tried three different types of brass black to see what I liked.  Don't remember exactly what I ended up using, but if you're ever interested I could look it up.

Anyway, you're not trying to blacken brass, but since you tried your stuff on brass and found it didn't work, I wanted to let you know that they are available!

Kim
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 15, 2020, 11:03:00 PM
Hi Kim -

Thank you for this. I probably won't be looking to blacken brass in this build, but it's always a possibility in future projects. Now that I know that it exists, it might get my mind ticking over. I'll come back to you for advice on which one was best if and when I decide to try it.

All good info, for me and perhaps others looking in too!

I'd be very interested to know if there are any compounds out there that will impart colours other than black to metals (other than plating or anodising I mean).

I'd love to get into anodising aluminium, but I don't have room for the gear. Mind you, lack of space has never stopped me before...
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 18, 2020, 11:19:20 PM
Made a start on the base today. The two big pieces of oak were joined together using jointing biscuits and exterior grade wood glue:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878732.jpg)

I love the smell of oak when it's being worked.

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878731.jpg)

In the following photo the glue hadn't yet been applied - this was a trial fit to make sure the biscuits lined up:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878734.jpg)

It has now been glued up and laid somewhere flat indoors. I'll release the clamps tomorrow. The pieces of oak are the shape they are because they were initially intended for another project, for which they were mitred. The pointed ends will either be cut square or shaped in due course, though it may be useful to keep a bit of extra length so that accessories can be mounted on them.

I then began marking out the blanks for the sides of the engine frame on a piece of 5mm thick aluminium plate:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/878733.jpg)

The sides will be made from the narrow rectangle at each end of the sheet of plate. The sheet is very precisely cut as purchased, so the existing edges will be good as reference lines for machining. A lot of the machining will be on the two sides at the same time, bolted together.

There will be more than enough plate left in that middle section to make a piece which will be fixed flat to the oak base under the engine, like a floor.

It was late afternoon by this time so I decided to leave setting up the saw to cut the plate for another day. This evening, I did a thorough clean-up of the mill to get all the cast iron swarf off it. Pleased to say it scrubbed up nicely. The lathe will be getting the same treatment, probably tomorrow.

Title: Re: A Simple Uniflow Engine
Post by: MJM460 on October 19, 2020, 12:20:51 AM
Wow, Gary, that ought to be enough biscuits! 

A pity. That so much of the oak will be hidden, but it should definitely be heavy enough to hold the engine down.

Good to see the progress.

MJM460

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 19, 2020, 09:30:30 AM
Ha, yes... as I have previously admitted I do tend to somewhat over-engineer things. That said, these are big heavy pieces of wood, so better safe than sorry.

Agree that it's a shame to cover so much of the wood, but I'd rather any oil and water fall on to a metal surface. Also, the wooden base will be quite a bit wider than the frame so there will still be a fair amount of oak visible.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 28, 2020, 11:37:24 PM
Misery.

My builder friend and his colleague were due to go and make a start on replacing my French workshop roof on Sunday. However, France has just gone into another national lockdown, so it's not going to happen.

I won't whinge, because this is affecting millions of people in ways much worse than it's affecting me.

My neighbour will do what he can with plastic sheets, etc., but I dread to think what state these machines will be getting into as it has done nothing but rain there for the past two weeks.

No progress on the engine (and have fallen behind with other people's threads that I'm following) as I have been redecorating our bathroom all week...

Sometimes this is how it goes...

 ::)
Title: Re: A Simple Uniflow Engine
Post by: propforward on October 29, 2020, 12:45:41 AM
Gary,

I heard that on the news today. I'm so sorry. However, I think the tarps will do a lot for you. Fingers crossed.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on October 29, 2020, 10:23:49 AM
Many thanks Stuart.

I have just learned that essential trades (including building) are likely to be allowed to continue, so it may still be on.

More later...
Title: Re: A Simple Uniflow Engine
Post by: propforward on November 01, 2020, 12:27:23 PM
Thatís great news. Any further word on that? I see the UK is heading into lockdown again.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 01, 2020, 12:30:29 PM
Yay!  :cartwheel:

My good friend and his helper are driving up to my place in France tomorrow to put a new roof on the workshop. France is in lockdown, but builders can work as it's an essential trade.

We have decided to go for a strengthened roof structure (more wood work plus tie-down straps), 'corrugated iron' instead of the dreaded fibro-ciment and a raised blockwork parapet to deflect the wind.

I'm hoping he will send me a few pics of the work in progress and if he does I'll post a couple here.

Meanwhile, here at home, I have finished redecorating our bathroom so should be able to get back to the engine soon, or at least give my shop a much-needed cleanup.

Things are looking up...
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 01, 2020, 12:31:30 PM
Thatís great news. Any further word on that? I see the UK is heading into lockdown again.

Stuart - yes - our posts crossed.

Yep, UK locking down again...

Title: Re: A Simple Uniflow Engine
Post by: propforward on November 01, 2020, 12:43:32 PM
Well thatís good news on the building front anyway! Glad to hear that at least.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 01, 2020, 12:50:16 PM
Cheers Stuart!

 :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 04, 2020, 10:27:04 PM
O Glorious Day!

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/880114.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/880115.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/880116.jpg)

And it looks like the insurance are going to pay...

 :)
Title: Re: A Simple Uniflow Engine
Post by: propforward on November 04, 2020, 10:39:51 PM
Wonderful news Gary! So glad to see that taken care of. Even better that the insurance will do what they are paid to do. Nice one!
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 04, 2020, 10:51:24 PM
Thanks Stuart. Very kind of you!

It was a happy moment when these arrived in my inbox.

Title: Re: A Simple Uniflow Engine
Post by: john mills on November 04, 2020, 11:36:28 PM
thats great to see the work happening  it is always sad to see machinery in the weather .i would like to check wats under the plastic   see the wd40 is not drying out and moister forming .good luck in recovery of the machines .
iI worked in a factory which had an explosion which lifted the roof .i was not on that shift when it happened
but the resultant fire made a mess but a recovery firm recovered the machinery in the end they said it was not bad
as they often get.but it was amazing what could be done.good luck with yours hopefully not too much .
  John
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 05, 2020, 01:14:39 PM
Hi John - thanks for your comments.

My friends will take the plastic off the machines as soon as the new roof is finished (which it may be by now). The idea is to dry off any remaining visible water, let them dry in the air for a while, then spray them liberally with WD-40. That's the best that we can realistically do until I can get over there (hopefully next year), at which point I'll have some cleanup work to do.

I'm a bit worried about water that may have crept into bearings and slideways by capillary action, but fingers crossed these will already have some protection from their existing oil and grease, and perhaps some WD will also help to drive any water out.

I bet you are glad you weren't on shift when the explosion happened! I hope no-one was seriously hurt, though by the sounds of it that may be a bit optimistic.

Good that the machines were salvageable though...

Title: Re: A Simple Uniflow Engine
Post by: propforward on November 05, 2020, 01:53:30 PM
Good approach Gary. I would be concerned about that capillary action too - but WD40 is REALLY good stuff, and its very specific purpose in life is water displacement - hence WD of course, so I reckon it will also capillary itself into those ways and kick the water out of there. I think you're doing all you can reasonably do, and I reckon it will go a long way to saving those machines, and make getting them up and running a matter of clean up and fettle, rather than restoration. Great that you have good friends and neighbours, can't beat that.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 05, 2020, 08:46:35 PM
Cheers Stuart.

Yes, WD-40 is 'Hydrofuge', and I'm hopeful that it will work as you say.I didn't know that's what the 'WD' stood for though!

Yeah, they're doing a grand job it would seem. Feels reassuring!
Title: Re: A Simple Uniflow Engine
Post by: propforward on November 05, 2020, 10:20:37 PM
Yes I understand it stands for "Water Displacement - formula number 40". I guess 1 thru 39 didn't amount to much. I should look into that and see if it's an urban myth or something.
Title: Re: A Simple Uniflow Engine
Post by: john mills on November 05, 2020, 10:29:18 PM
Hi Gary

when the explosion happened they where  very lucky just people had moved at that time from and of the critical places  apiece of plaster board was stuck between the bench top and the steel frame just behind where the operator would stand at the lathe i operated the day shift person also was not there at that time only miner injuries to 2 people  could of been very different .as for the machines they were recovered .the recovery people told me they often recover machines be cause it was quicker than waiting for new replace ments i would think it would have been a good opportunity to replace old machines with new ones .   
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 06, 2020, 09:27:08 AM
I guess 1 thru 39 didn't amount to much. I should look into that and see if it's an urban myth or something.

I like it!  :Lol:

My only doubt is that I have heard that originally it's a German product. Don't know if that's true or not, and even if it is it may still have been named in English I guess...

@ John - glad to hear no-one was seriously hurt. One hears enough horror stories as it is these days.

Cheers guys.

 :ThumbsUp: :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 07, 2020, 11:55:48 PM
Great progress, and quick too:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/880410.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/880411.jpg)

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/880412.jpg)

No doubt the devil will be in the detail (as I'll discover when I can eventually go back to France), but from the photo here everything looks much better than I dared hope...

Back to the engine again soon, after this major diversion...
Title: Re: A Simple Uniflow Engine
Post by: Jo on November 08, 2020, 08:28:41 AM
Pleased to see the roof back on Gary  :ThumbsUp:

Now it can dry out and hopefully any surface rust can quickly be cleaned off  :)

Jo
Title: Re: A Simple Uniflow Engine
Post by: Admiral_dk on November 08, 2020, 09:50:39 AM
What a relief it must be for you to see those pictures of a nice roof on your workshop again  :LittleAngel:

I bet you will still be somewhat anxious when you finally get to see them in the flesh again, and start inspecting them for any damage ... but it should much better than without a roof ....

Best wishes

Per
Title: Re: A Simple Uniflow Engine
Post by: propforward on November 08, 2020, 03:31:40 PM
Much better! Looks great Gary, pleased to see that progress! Very nice workshop, too.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 08, 2020, 09:45:15 PM
Jo, Per, Stuart -

Thank you! Your support is much appreciated.

From this distance it all looks pretty much like it was before. It is of course very possible that there will be some damage at a more detailed level, and yes inevitably there will be some surface rust.

But I spoke to my builder friend on the phone today (he is back at home now) and he said that things aren't looking too bad and that he liberally sprayed all of the machines with WD-40 and something else similar, so they will now sit there for a few months like that, which - as you note, Per, is way better than them sitting exposed to rain! And the workshop now has a much better roof than it did before.

Stuart - glad you like my France workshop. It's pretty basic, rough and ready but it has soul! All I have done in there so far is work on machine restoration, which is something I enjoy. If one day I spend more time over there, the remit may broaden.


Now, at last, back to the engine:

No spectacular progress today but it was good to reconnect. The oak base was made in two halves which were fixed together with exterior grade wood glue and lots of jointing biscuits and clamped tightly while the glue set. Despite (or more likely because of) me having tried to make the thing bombproof, it ended up with something of a misalignment in that looked at from the end the two pieces would be seen as a very shallow v shape rather than a straight line. One one face of the assembly the pieces appear to meet nicely, but on the other (which for obvious reasons I have decided is the bottom) there is a narrow gap. This is annoying, but it's not a disaster as the faces can be planed flat, and it's plenty thick enough. This picture shows the underside as I 'm just about to start with the power planer:

(http://www.model-engineer.co.uk/sites/7/images/member_albums/173350/880521.jpg)

And this one shows the top of the base after an initial rough planing:

(http://www.model-engineer.co.uk/sites/7/images/member_albums/173350/880522.jpg)

Ideally this would be run through a thicknesser to make it flat and even. I have one as an attachment to my wood lathe but it's not big enough for this job. I'm sure that a local joinery would do it for me but I like to do things myself as far as possible so the next step will involve a hand plane and a sander, with repeated use of the straight edge  to check for high spots.

As I've mentioned somewhere above, the base will not end up this shape - it's only like this because the pieces were left over from a sidelined project.
Title: Re: A Simple Uniflow Engine
Post by: MJM460 on November 09, 2020, 09:47:45 AM
Hi Gary, good to see that roof on again already.  Looks like it will be even better than brand new.

Now that the roof is good and the plastic covers off the machines, the WD40 will be evaporating clean away, hopefully along with the water.  (After all displacing it does not make it magically disappear.  I really donít know what happens to it in this situation.)    I would be thinking about a follow up protective spray.  Something that leaves a protective coating this time.  Here, suitable products would be CRC, which stands for corrosion resistant coating, or Innox.  I donít know how widespread these brands are, but there will be similar products available everywhere.  Of course this would depend on the help of your willing neighbour.

Other forum members might have better ideas.  And just having the roof repaired is excellent progress towards having it all in operation again.

MJM460

Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 09, 2020, 11:45:11 PM
Hi MJM -

Yes, it looks to me much better than the roof it has replaced, even before it was broken.

Good suggestion re the protective sprays - I'll give it some time for the machines to dry out, then look into it.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 12, 2020, 10:23:35 PM
Seem to have been bogged down in lots of other stuff recently, with not much progress on the engine.

Four of these arrived today - a small step but better than nothing. Feet for the underside of the oak base, with threaded inserts to screw them into:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/880855.jpg)

They are quite substantial (the thread on the stud is M10), and I love the orange rubber pads!
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 15, 2020, 10:22:09 PM
Squaring off the ends of two lengths of 40mm aluminium angle. These will be fixed to the oak base, one on each side of - and parallel to - the engine. Let's call them frame mounting bars. The two main sides of the engine frame will be fixed to the vertical face of these bars.

Not very exciting stuff, this, so apologies. However, I was just glad to get into the workshop this evening after being bogged down with fireplace problems, camper van problems, dishwasher problems, cracked bathroom floor tile problems, and writing a work-related article that I wish I hadn't agreed to. So happy to post a plain old shot of the mill set up to tidy up the ends of some unexciting aluminium angle. At least it shows my new vice, this being the first time I have used it:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/881146.jpg)

I thought I'd also let you see these in their unused state:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/881148.jpg)

They were cheap as chips on Amazon, so whether they will last longer than five minutes remains to be seen. But at the price it's not much of a risk. I like the fact that I'll be able to see how much oil is in them. They also each come with two interchangeable nozzles, and the pump mechanism does feel quite sturdy. Time will tell...
Title: Re: A Simple Uniflow Engine
Post by: propforward on November 16, 2020, 12:28:12 AM
Nice. A bit of workshop time is always good medicine to get the head straight around that "other stuff". One of the reasons I like model engineering, is because it does actually take some brain power, so good for getting your mind off every day things for a bit.

That is an immaculate mill! Always good to see a well looked after shoppe.

That's a good looking vice. I'm looking forward to seeing all manner of set ups with it.  :ThumbsUp: :ThumbsUp: :ThumbsUp: :ThumbsUp: :ThumbsUp:
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 16, 2020, 11:29:32 PM
Stuart - agreed, absolutely. I find that I get very frustrated when all of the other stuff (which I've had plenty of recently!) keeps me away from the shop. Another thing happened today... but no. Enough of that!

I wish I could tell you that my mill is always that clean though.

Normally it's anything but...

 ::)
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 22, 2020, 11:22:56 PM
Assembling flatpack shelving units, more work on the campervan, earning a living... oh - and drilling a few holes:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/881802.jpg)

These are drilled in the frame mounting bars so that they can be fixed to the oak base with wood screws. Modest progress, but now I can start on the two sides of the frame, so I'm at a significant stage of the build...
Title: Re: A Simple Uniflow Engine
Post by: propforward on November 22, 2020, 11:34:29 PM
Lovely work Gary. Good finishes - always enjoy seeing your posts.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 23, 2020, 08:07:42 AM
Cheers Stuart.

Hoping to make a bit of progress next weekend...
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 24, 2020, 10:14:15 PM
Now... a template for the sides of the frame, cut out of thick paper:

(https://www.model-engineer.co.uk/sites/7/images/member_albums/173350/881909.jpg)

The two sides of the frame will be cut to this shape from 6mm aluminium plate. Two pieces will be bolted together to keep them both the same shape as they are cut with saws and finished on the large belt sanding attachment on my woodturning lathe. No CNC here! (maybe one day...). The aim is to end up with a simple but elegant curve on each side of the engine, forming the frame. These will be fixed to the frame mounting bars, which in turn will be fixed to the oak base. Holes will be drilled for the two main bronze bearings. These will be high enough so that I can increase the diameter of the flywheels if I need to for the engine to run (in the photo both the flywheels and the cylinder are temporarily shimmed with wood, for height). The whole structure will be braced by cross members made from round aluminium bar running between the two sides of the frame. Also, two shorter cross members will tie each frame side to the cylinder, which will be supported at centre height by an aluminium block. The roughly scribbled circles on the paper represent the fact that 'decorative' holes will be cut into the frame sides wherever they will look good and not interfere with the 'functional' holes for the bearings and cross members. A rectangular aluminium plate will be installed under the whole length of the engine so that oil and water will not drip on to the oak (which nevertheless will be treated with several coats of Danish oil).

That's the plan, anyway, subject to any changes of direction that may occur as I go.

Hope to start shaping these frame sides at the weekend.

And it looks like the insurance company are going to fork out for my French workshop roof...  :)
Title: Re: A Simple Uniflow Engine
Post by: propforward on November 24, 2020, 10:29:22 PM
Good news all round Gary.

Like your idea for the frame - should set the engine off nicely.
Title: Re: A Simple Uniflow Engine
Post by: gary.a.ayres on November 24, 2020, 10:30:29 PM
Thanks Stuart.

Still a long way to go though...  ;)
Title: Re: A Simple Uniflow Engine
Post by: propforward on November 24, 2020, 10:38:01 PM
Always!  :ROFL: