Author Topic: A Simple Uniflow Engine  (Read 3161 times)

Offline gary.a.ayres

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Re: A Simple Uniflow Engine
« Reply #75 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
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:

Online crueby

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Re: A Simple Uniflow Engine
« Reply #76 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:

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.

Offline Jasonb

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Re: A Simple Uniflow Engine
« Reply #77 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.

Online crueby

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Re: A Simple Uniflow Engine
« Reply #78 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.

Offline gary.a.ayres

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Re: A Simple Uniflow Engine
« Reply #79 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.

Online crueby

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Re: A Simple Uniflow Engine
« Reply #80 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.

Offline gary.a.ayres

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Re: A Simple Uniflow Engine
« Reply #81 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...

Offline gary.a.ayres

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Re: A Simple Uniflow Engine
« Reply #82 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:



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:



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:



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



And so, state of the art so far:



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


Offline Jasonb

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Re: A Simple Uniflow Engine
« Reply #83 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.

Offline simplyloco

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Re: A Simple Uniflow Engine
« Reply #84 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

Offline gary.a.ayres

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Re: A Simple Uniflow Engine
« Reply #85 on: July 06, 2020, 09:58:22 AM »
Jason and John - thanks.

Drain cocks it is.

 :ThumbsUp: :ThumbsUp:

Offline MJM460

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Re: A Simple Uniflow Engine
« Reply #86 on: July 06, 2020, 11:44:57 AM »
Hi Gary, thinking in particular about the “uniflow” 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.

It’s looking good so far.

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 Simple Uniflow Engine
« Reply #87 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

Offline gary.a.ayres

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Re: A Simple Uniflow Engine
« Reply #88 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...



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



... 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:



And here is the story so far:



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

gary




Offline simplyloco

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Re: A Simple Uniflow Engine
« Reply #89 on: July 07, 2020, 11:43:58 PM »
I look forward to seeing this run!
John