Author Topic: A Beginner's First Engine (Single-acting Oscillator)  (Read 896 times)

Offline gary.a.ayres

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A Beginner's First Engine (Single-acting Oscillator)
« on: February 10, 2019, 11:34:07 PM »
This is my first ever attempt at building an engine, so I decided to keep it as simple as possible and start with a half inch (12mm) single acting oscillator. Given the levels of knowledge and skill that many of you have I suspect you may find such a basic build less than exciting, though I am adding a couple of touches of my own to the project which may take it a little bit away from the ordinary.

Fundamentally the engine will be a version of the single-acting oscillator designed by Steve of Steve's Workshop http://steves-workshop.co.uk/steammodels/simpleoscil/simpleoscil.htm, where plans and guidance are posted. My main reason for choosing this version out of the many similar engines that are out there is that like most of my tooling, it's metric. My version differs from Steve's original in a few non-critical dimensions due to the materials I have available. I have also opted for a particular look of my own devising which has nothing whatsoever to do with functionality. Call it steam meets dieselpunk meets Flash Gordon...

I marked out the frame on 12mm aluminium plate and the pulley on a slice of brass bar, making sure that the frame was bigger in all dimensions than the rectangular frame of the original:



I can hear you gasp at what is to all appearances a very scrappy bit of marking out. However, there was method in my madness. CNC would be perfect here (one day...) but I used the same approach that I have used to create irregular but clean-edged forms in abstract paintings such as 'Trident', below, where I would sketch roughly on the canvas in pencil first, then gradually refine the lines with paint until I got the forms I wanted:



 I did the same with the engine frame,  but instead of refining the form with acrylic paint and brushes, I tried a variety of tools and methods before settling on a combination of chain drilling and small drum sanders of various sizes held in the mill chuck. I'd rather have used my drill press for this but the vibration shook the MT3 shank  of the chuck out of the spindle (why don't drill presses have drawbars as standard...?).

If the flywheel looks oversized relative to the frame it's because it is. It needs to be turned down to size.

The bottom of the frame needed to be trued up then drilled and tapped to to make two threaded mounting holes to attach it to the base. I attached it upside down to an angle plate using two toolmaker's clamps, then checked the level of the scribed line with a height gauge before squaring the piece with an endmill and drilling and tapping it M5:





A recess was then milled in the flywheel using my small rotary table with its four-jaw self-centring chuck:



And that's as far as I have got so far. Pictures below. A reasonable start I suppose:







 :)




Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #1 on: February 10, 2019, 11:43:11 PM »
Good choice on a first engine, its where most of us started out, you will learn from it and move up quickly, jusdging by your other work!
 :popcorn: :popcorn:

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #2 on: February 10, 2019, 11:46:25 PM »
Looking good Gary, it's nice to see a new approach to standard design  :)

Offline Johnmcc69

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #3 on: February 10, 2019, 11:52:39 PM »
 :ThumbsUp:
Excellent start Gary! Parts looking good!

 John

Offline AOG

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #4 on: February 10, 2019, 11:57:21 PM »
Itís looking good but I do have a general suggestion based on my own painful experience. When you are going to do a shaped part like that do the shaping last. Start by squaring up a rectangular blank. The straight edges make it very easy to align and hold the part while you put in the interior holes and features. When those are in then shape the outside. It isnít going to be much of a problem with the part you are making now but trust me, the lack of good square references can bite you.

Tony

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #5 on: February 11, 2019, 12:04:27 AM »
Many thanks gentlemen.

@ Tony - yes, that makes sense. Next time...!

Offline b.lindsey

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #6 on: February 11, 2019, 12:58:04 AM »
Always enjoy watching first engines Gary. I am excited along with you and will definitely be following along.

Bill

Offline 10KPete

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #7 on: February 11, 2019, 03:04:52 AM »
 :popcorn: :popcorn:

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #8 on: February 11, 2019, 09:30:43 AM »
Many thanks guys - very kind of you.

gary

Offline Ramon

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #9 on: February 11, 2019, 10:05:10 AM »
Congratulations on making that start on your first engine Gary :ThumbsUp: I remember it well. Believe me when you see it run for the first time you will have a grin from ear to ear :D

I would reiterate the sound advice offered by Tony - get the parameters right before letting those obvious creative juices you possess take hold - work the outside to the details and not the other way round  ;)

Good luck with the rest of your build - your perseverance with your boiler will hold you in good stead :ThumbsUp:

Tug
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(a very apt phrase - thanks to a well meaning MEM friend)

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #10 on: February 11, 2019, 10:21:29 AM »
Thanks for this Ramon - much appreciated.

Now that it has been pointed out to me it's very clear that it's better to keep things square for as long as possible and leave the fancy stuff to the end. I reckon I'll get away with it this time, as Tony says, but I can see how it could be a big problem with more complex parts.

I was partly driven by enthusiasm for my idea but also partly by uncertainty about how easy it would or wouldn't be to make curves of this kind in aluminium plate given the limits on the equipment I have. I didn't want to drill all the ports and so on, only to then spoil the piece when trying to shape it. Now that I have found a way of making these curves it should be easier to leave it until the end in future builds.

Cheers,

gary

 :ThumbsUp:

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #11 on: February 11, 2019, 10:31:08 AM »
Believe me when you see it run for the first time you will have a grin from ear to ear :D

Tug

PS - yes - I can't wait for that moment!   :)

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #12 on: February 11, 2019, 11:46:43 PM »
Another session today. First, a recess was milled on the flip side of the flywheel to match the first one:



Most of the subsequent work on the flywheel will be done on the lathe. To try to avoid a wobble, I intend to turn it in one setting, between centres on an arbour made of the same stock as the main axle.

The base was then marked out on a piece of the same aluminium plate as was used for the frame. It was also marked out in a similar style. Gives new meaning to the term 'scratch built'. Or maybe that's where the term came from in the first place:



I swear I'm starting to like the smell of that stuff just a bit too much...

This time, as I had only external curves to deal with, I used a coarse grit on the belt sanding attachment of my Coronet Major woodturning lathe to shape the piece, followed by a medium grit flap wheel in the drill press. As it happened I did not work to the scribed lines because a pleasing shape began to emerge before I reached them, so I just flipped the part over, gave it a few more passes on the sander and called it done, minus the finishing. I used M5 transfer screws to transfer the hole positions from the bottom of the frame to the base:



The position of the frame on the base was judged by eye, but the distance between the holes needed to be retained, hence the transfer screws. First time I've ever used them, but it will not be the last   :ThumbsUp:

Once the clearance holes were drilled, they were counterbored on the underside of the base to accommodate the heads of the M5 cap head screws:



Looks a bit spooky here, but less so since I cleaned off the layout fluid...

Finally, the frame was screwed to the base:










Offline crueby

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #13 on: February 11, 2019, 11:56:11 PM »
Great progress!


 :popcorn:

Offline b.lindsey

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #14 on: February 11, 2019, 11:56:20 PM »
Very nice looking shape to it Gary. I noticed on the second picture in this post it looks like a 3D effect. No doubt just the combination of colors and patterns but I did do a double take. Was looking on my phone though. Anyone else getting the same effect....kind of cool.

Bill

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #15 on: February 12, 2019, 12:03:09 AM »
Many thanks guys.

Your interest and support are greatly appreciated.

 :)

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #16 on: February 12, 2019, 12:05:32 AM »
I noticed on the second picture in this post it looks like a 3D effect. No doubt just the combination of colors and patterns but I did do a double take.
Bill

Yes, now that you mention it it does look like the blue floats above the background. All I did was up the contrast and brightness slightly and sharpened it up a little (like I do with most photos).

The blue really pops!

Offline cnr6400

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #17 on: February 12, 2019, 02:31:11 AM »
Great progress Gary, well done!  :ThumbsUp: :popcorn:

Offline Ramon

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #18 on: February 12, 2019, 07:08:41 AM »
Hi Gary, your engine will certainly have some character  :ThumbsUp:

A thought, as I can't see you've mentioned it - your standard is aluminium - I assume you will be making the cylinder from brass? If so, I would bond a brass wear plate to the standard where the cylinder pivots against as aluminium will quickly wear and possibly score quickly spoiling the seal. Were you thinking of it, a cylinder made from aluminium will gall and pick up even more so. Brass to brass is fine - aluminium to aluminium is not.

Standard epoxy with a couple of small pins would be fine.

Hope you don't mind the comment - Tug
« Last Edit: February 12, 2019, 08:53:55 AM by Ramon »
"I ain't here for the long time but I am here for a good time"
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Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #19 on: February 12, 2019, 09:45:50 AM »
Thank you both.

@Ramon - my plan is to use brass for the cylinder. In the Steve's Workshop plans he uses brass for the standard and the cylinder. I decided to use aluminium because I had some available but also because I fancied the look. I have in fact been wondering how the ali would stand up to wear, and the idea of some form of protection had occurred to me but only in a vague and unformulated sort of way and I had no clear thought about what to do about it. So thank you for your suggestion, which I will follow.   :ThumbsUp:

Similarly, in the plans the brass standard is bushed with bronze for the main axle, but the narrower cylinder pivot just goes straight through a hole in the brass. I'm now wondering if - given I'm using aluminium - whether the hole for the cylinder pivot should also be bushed?

Cheers,

gary

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #20 on: February 12, 2019, 10:21:56 AM »
Taking shape nicely, not sure how well a piston will run in a matching curved cylinder though  ;)

As for the bushing, as you are taking the time to make a more elaborate 'delux' oscillator it makes sense to spend another 10 mins making one even if it isn't essential.

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #21 on: February 12, 2019, 10:57:47 AM »
No problem Peter. Banana-shaped piston.

On the bushing - I agree   :)

Offline Ramon

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #22 on: February 12, 2019, 11:24:39 AM »
Hi Gary, yes I would agree with Peter it would be well worth putting a bush in. The humble oscillator may have a simplicity about it but it still has it's issues that can easily be improved upon.
The main one is usually the lack of true squareness of the pivot to the cylinder block and the subsequent misalignment and wear that rapidly results as a consequence.

One way to overcome that problem is to make the pivot a composite one - a short stud in the cylinder with the pivot pin itself tapped a slightly loose fit which will then pull up to the  face square in both directions. The other benefit gained from this is that the pin is not pivoting on a threaded surface but a smooth one which can be made much larger in diameter for a much better wearing surface - within the constraints of any internal passage ways of course.

The pin can be made as a simple tube tapped right through and faced square on the end with a further stud to lock it or can be made as one piece as in the image (Note 'stud' here need only be a piece of threaded rod)

This should give you the idea


Hope that's of use - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #23 on: February 12, 2019, 11:43:13 AM »
Tug, the idea of a composite pivot makes a lot of sense and is a simple solution  :)

I watched a video by mrpete222 on youtube recently, the way he ensures squareness of the pivot is to drill right through the cylinder so that if there is any out of squareness on assembly he passes a rod right through the cylinder then machines the port face square in the lathe. Once all is ok he plugs the extra hole.  I can see the idea working but it seems to me like an awful lot of messing about.

Offline Zephyrin

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #24 on: February 12, 2019, 11:47:04 AM »
Hi Gary,
don't forget that large chunks of metal to heat make starting difficult for a little steam engine...
I agree with the upper statement on aluminium and brass together, and with a bronze bushing.

the cylinder pivot hole has to be absolutely perpendicular as should be the cylinder face with its axle for a good runner.

Offline Jasonb

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #25 on: February 12, 2019, 01:12:16 PM »
Off to a good start Garry. We had best not tell you about the RMC engines as you will get even more carried away with the unusual shapes :-X

J

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #26 on: February 12, 2019, 01:28:59 PM »
Thank you all  :)

@Tug - yes, the composite pivot idea makes a lot of sense in terms of solidity and a snug perpendicular fit. I'll most probably go with it.  :ThumbsUp:

@ Peter - agreed - mrpete222 is a treasure but when I first saw his practice of drilling right through the cylinder then plugging the outer hole (in one of his earlier oscillator builds) I thought 'hmm... I don't fancy that much...'.

@ Zephyrin - I'll try to get it as perpendicular as possible. Also, I have just ordered a bunch of nice metric reamers to make proper holes with in this and in future projects (heck, it's not cheap, this game...). On having a lot of metal to heat - I'll be honest - I never thought of it. I do plan to make some decorative holes in the standard once everything else is done and I can see what room I have left and according to the look (you can see some roughly sketched in on the first picture at the start of this thread). The flywheel will also have a circle of holes drilled through the recessed part. I don't know if these will make any difference but in the worst case scenario I could always radically revise the whole standard. Hopefully it won't come to that, though I have picked up that you know quite a bit about the thermodynamics of such things   :)

@Jason - RMC engines, eh? Aha... Google is my friend!   ;)

Cheers,

gary

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #27 on: February 12, 2019, 01:35:43 PM »
We had best not tell you about the RMC engines as you will get even more carried away with the unusual shapes :-X

J

Just took a look, and I like! Ideal for a browse later when I have more time.

If I ever get any good at this, and when my little furnace is operational.... *daydreams about exotic engines of the future...*   8)

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #28 on: February 12, 2019, 06:43:45 PM »
Just a thought Gary but if you are interested in making engines with an artistic flair have you considered buying a set of French curves?

They cost next to nothing but could prove useful in marking out curved profiles etc.

https://www.ebay.co.uk/itm/French-Curves-Technical-Draughtsman-Drawing-Stencil-Set-of-3-Ruler-Template/191907678398?epid=1675145184&hash=item2cae96c8be:m:mXWeUGxp5qpxareDktwawpA:rk:7:pf:0


Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #29 on: February 12, 2019, 07:17:22 PM »
Peter -

that's a really good idea. I don't foresee any more curves on this one, but may well procure a set for the next one.

 :ThumbsUp:

gary

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #30 on: February 12, 2019, 11:41:08 PM »
This evening I started working on the cylinder and the main axle.

The plans call for a piece of 25 mm round brass bar as the starting point for the cylinder. I found one small piece among some offcuts on my shelf. It was only a little longer than the required 30 mm and by the time I had faced it at both ends (which entailed a silly mistake that I should not have made) it was 29.65 mm long. I know that 0.35 mm is actually quite a lot, but I assume that in a single acting oscillator the length of the cylinder isn't critical to that degree. The alternative would be to order some more brass bar online (as these materials are hard to get hold of where I live) and that would seem to be overkill for 0.35 mm off the length of an oscillator cylinder. However, please correct me if I'm wrong.

The main axle is 6.0 mm in diameter in the plans. The nearest I had was round bar of 6.25 mm diameter in what I think is silver steel (it came as part of a whole bunch of stock with a Myford lathe that I bought from a man who had built a loco). I turned a length of it down with very light cuts and polished it with emery paper. It's now sitting at about 6.10 mm and I think it will need some further polishing but I'll leave this until my new reamers arrive and make a 6 mm reamed hole to test the axle with so I can hopefully bring it to a nice running fit. The length is arbitrary at this point - I deliberately left it on the long side because I might put a pulley on it at the end of the build, and in any case better too long than too short at this point.

Pictures:





I'm unlikely to be doing anything to the engine now for about a week as I have to work for the next two days and am then visiting my daughter for a long weekend...


Offline b.lindsey

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #31 on: February 13, 2019, 12:30:32 AM »
You can likely adjust the thickness of the piston to compensate for the slightly short cylinder. Shouldn't be a big issue.

Bill

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #32 on: February 13, 2019, 06:09:16 AM »
Bill - that had occurred to me. I can look at that if needs be.

Thank you.

gary

Offline MJM460

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #33 on: February 13, 2019, 07:03:32 AM »
Hi Gary, itís coming on well and will look interesting when you have it finished.  (Unlike my square blocks.)

While 0.35 mm is a long way out for a 3 mm bolt hole, let alone the shaft bearing diameter, it may not matter at all, or even improve things when in the cylinder length.

Draw a little sketch with the crank at top dead centre.  Calculate the distance through the frame from the crank shaft cylinder pivot pin and inside of the cylinder top head.  Then calculate from the shaft through the crank pin at top dead center, piston rod and piston.  Then you can do the subtraction to see how much clearance there is above the top of the piston.  If it iis supposed to be around millimetre, a reduction by 0.35 will not matter.  The main thing is to keep an eye on that clearance at top dead centre and not allow it to disappear as other components are made with their inevitable tolerances which inevitably add up the wrong way.  That is what Murphyís law is all about.

The piston sides are the bearings through which the piston causes the cylinder to oscillate, and longer is better, so long as the bottom of the piston stays within the cylinder.  So if you do run out of clearance at TDC, I would suggest making the piston rod a little shorter rather than shorten the piston.  Though you also have to check that the crank web/disk clears the bottom of the piston (and cylinder) as it goes through TDC.

That is why an oscillator is such a great place to start, even with such a simple engine, there is so much to learn as you build it up.  With more parts in a more complex engine, there are more places where the dimensions of one part affect the clearances for another.  Part of the preparation before you start on a more complex model, is to identify these critical dimensions.

Like your boiler project, you are learning so much from each step.  Well done.

MJM460



The more I learn, the more I find that I still have to learn!

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #34 on: February 13, 2019, 10:12:40 PM »
Thanks for your kind words MJM460.

I take your point about shortening the rod rather than the piston. I didn't get it at first until I realised what you said, i.e. the piston causes the cylinder to oscillate (or at least is the final link in the system that does so), and the force for the lateral movement is transmitted through the sides of the piston. It seems to me that for this reason piston length could be more important in an oscillator than in a fixed cylinder engine...?

Not sure how much difference that 0.35 mm will make in my case, but I will carry out the calculation you suggest because I plan to have a go at machining the piston assembly as one, so it won't be possible to shorten just the rod after it's made. It would be different if the piston head and the rod were two components.

I think your engines and plants look great, btw.

Offline MJM460

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #35 on: February 14, 2019, 03:52:37 AM »
Hi Gary, yes you have got it on the piston length.  The calculation will tell you if you need to make any adjustments to the position of the crank pin bearing location before you finish off that end of the rod.

And yes, if the design has a rod packing and cross head, both of which keep it pretty square, the piston does not have to be so long.  Just enough for rings, or grooves or what ever you are doing to reduce leakage past the piston.  But at the same time, those same components have to be lined up very well or will result in extra friction, which is an extra complication for a beginner.  You already know more about what you will need to do, just from the experience of building that oscillating engine, things that are not always so obvious from a first look at a design.  Drilling a hole is easy, getting it in the right place is more difficult, and if you really need a precise location or alignment, another level again.

Thanks for your comments about my engines.  I think I was a bit harsh on myself, after all Elmerís engines are mostly square, along with so many other designs, and they all look pretty good.  I was just saying that I donít have the artistic flare that you clearly demonstrate in your projects.

MJM460

The more I learn, the more I find that I still have to learn!

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #36 on: February 14, 2019, 06:22:01 AM »
Yes - I'm with you regarding the piston. The calculation will tell me by how much the crank pin bearing needs to move by, as you say. That's the right way round to look at it. Even if the difference in this case proves to be insignificant in practice, it will be good experience for me to do the sums anyway.

Agree re Elmer's engines - there was a real aesthetic sensibility going on there, alongside the creative engineering. A lot of them are quite rectilinear in style but graceful nonetheless in a modernist kind of way. His #36 reversing wobbler is a good example of that I think.

Thanks again for your interest.

gary

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #37 on: February 15, 2019, 01:07:29 PM »
Just a thought Gary but if you are interested in making engines with an artistic flair have you considered buying a set of French curves?

That was a good suggestion Peter, and in response I have ordered these:



I won't need the actual French curves until I start another project of this kind, but the small circle templates will come in very handy for laying out the decorative holes that I plan to make in the standard of this one when it's done.

 :ThumbsUp:

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #38 on: February 15, 2019, 01:11:28 PM »
You can likely adjust the thickness of the piston to compensate for the slightly short cylinder. Shouldn't be a big issue.

Bill

Bill - I'm sure that's right, but having thought a bit more, given I'm a newbie at this and working from the plans, I decided not to take any risks with getting the ports to line up as exactly as possible. Probably being over-fussy but no harm. I also remembered that to get more bar I wouldn't need to order online, as a local small engineering firm owned by one Adrian have a scrap bin which is a veritable treasure trove. I found a piece of 25 mm brass bar at 37 mm long, which he kindly gave me for nothing. Perfect!

I'll turn it down to 30 mm and carry on with the build next week when I come back from my daughter's.   :)

Offline Gas_mantle

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #39 on: February 15, 2019, 01:21:52 PM »
Gary, where did you order the curve stencils, I thought about buying some but the ones I've seen don't come with the regular shapes like circles, triangles etc.


Offline Jasonb

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #40 on: February 15, 2019, 01:29:08 PM »
The curves look to be knock offs of Rotring ones and some orange copies of Linex templates for the others.

Regarding the cylinder with such a small difference in length you could just leave the end cap a little thinner and have the piston travel  closer to the open end, provided you set out the ports from the pivot point it won't make any difference and you can put the extra brass away for the next engine.

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #41 on: February 15, 2019, 03:06:04 PM »
@ Peter:    https://www.amazon.co.uk/gp/product/B079L1XGKH/ref=ppx_yo_dt_b_asin_title_o01__o00_s00?ie=UTF8&psc=1

@ Jason: I have no doubt you are correct. However, I've already started on the new bit of brass (quick fix of shop for 20 minutes before I  head off) and in any case it will be good practice for me to work to a plan as exactly as I can (apart from the frame and base of course!) for my first build. I guess a better understanding of the various tolerances will come in time. I'll keep the first bit of brass for the next engine, so nothing wasted.   :)

Cheers both   :ThumbsUp:

Offline JC54

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #42 on: February 15, 2019, 07:49:21 PM »
Hello Gary, this is the first engine that I made, mainly because it had no silver soldering. I just measured my cylinder and it is 29.85mm the piston protrudes 1.84mm when at BDC. It runs really well and will tick over at 2psi. One thing that I did find was that I lapped the cylinder and piston and then drilled holes for the endcap bolt threads. These made a slight "bulge" into the cylinder so I had to lap again. Next time I will drill and tap holes before final reaming/lapping.
     As several people have said it will take days to get that silly grin off your face when it first runs. I am now on my second engine a very simple beam engine. Best of luck John :old: :DrinkPint: :DrinkPint:

Offline gary.a.ayres

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Re: A Beginner's First Engine (Single-acting Oscillator)
« Reply #43 on: Today at 01:05:18 AM »
Hi John -

thanks for the encouragement and advice.

I'd never have considered that the screws for the end cap could cause a bulge. Well worth being aware of.

Best of luck with the beam engine   :ThumbsUp:

gary