help with steam engine

And for that matter, where do you get cast iron for piston rings? I've seen centrifugally cast recommended, but how do you get your hands on it? Regular cast is $$$ from McMaster -- can I just visit my local engine rebuilder and saw the snouts off of a bunch of trashed crankshafts?

I'm not that much a steamer ...

The less the better. 2..3/100 mm is good enough (with a ring). Get a good surface!

The CI-ring will wear in and forgive your extra clearance. In a first attempt, I would use the CI-ring. It will smoothen the cylinder by time. Later, if you are not content, you can always fit a teflon ring.

It would be better, if your surface is very smooth. I've heard that the "Vitron"-brand is best. I guess it's some kind of PTFE.

HTH, Nick

Chuck,

I am plowing the same ground. I'm working now on a PM Research boiler for an old Tiny Power engine. Tiny Power includes a groove for 2 rings. They imply you can either make CI rings or use teflon tape packed in the groove for a piston ring. Teflon tape and saturated steam probably will make a pretty good ring for use on saturated steam. Another approach I have used on small cylinders, is to make the piston a very close moving fit and cut some shallow grooves in it to act as "rings" with retained moisture.

You can use the same CI that you use for the piston. Even better, you can make the ring and the piston in one pass.

That would be hard. You could ask manufacturers of cylinders (just the sleves). But I doubt they do have the sizes you want. Centrifugal CI is mostly used for cylinders in cars.

A crancshaft? It will be hardened. CI from continuous castings *) isn't that expensive. But, you get a lot of swarf ... err coal making a piston ring out of round stock. :-)

*) Don't know how you call it. It is a continuous process using a water cooled, tube shaped copper mold.

Nick

I looked at a tiny power kit a long time ago. At that time he was recommending and including graphite string in the kit. Don't know what he does today.

I build the coke bottle PM research engine. The plans called for a tiny teflon ring but the teflon supplied was cut from a sheet and was not made from string.

chuck

I just checked -- it's way less expensive than I remember; much more in line with what I thought it should be. Now where did I get the idea they wanted 10x more for it than it is?

So if you don't make rings from round stock what do you use and where do you get it? The "cast iron pipe" you get around here is just cruddy mild steel.

No, I make it from round stock. What I wanted to say is: If you make the piston, make the shirt a bit longer for the ring. Make the same outer diameter as the piston, inner diamerter per specs, a bit deeper then the thickness of the ring. Then you part the ring off. Voila!

Take the finest blade you can find for your jig saw and split the ring. Now, put some iron crap laying around (your shop isn't messy?) and put it into the gap you just sawed. Put the ring between to steel plates that you screw tight (one screw in the center). Heat the "burger" up to a dull red and keep the heat for 5 minutes. Let cool down, open the sandwich and remove scale on the ring with an oilstone. Next, you continue with the ring groove in the piston and use the ring as a reference.

You didn't want to hear that? OK, maybe someone else. :-)

That kind of CI-tubes was in use for shit-pipeing.

Nick

Now I know! We call it by the name: "L-Ring". Thanks.

Haven't made one. Turning it wouldn't be that diffcult, but baking in the tension would distort him. I guess.

Nick

My dad and I made a steam engine a long time ago. We cut open shock absorbers and used the cylinders and pistons inside for parts. Worked good.