steam engine need help!

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Re: steam engine need help!

Post by rkcarguy » Wed Dec 27, 2017 1:01 pm

Joe, I have about 15 years of experience in machine work, fabrication, and mechanical work, as well as some design of all 3. I've been into every part of a car/truck from rebuilding a brake master, assembling engines, to rebuilding a brake caliper that was hard to find a replacement for. I also built a very basic little 1" bore steam engine in tech school but only ran it on air. It was a simple thing that was aluminum on aluminum, but used Teflon rings top and bottom so the piston never touched the bore. I made a little billet connecting rod and even put bearing bronze in it, and offset turned the crank on the lathe in one piece from steel. One of the reasons I was able to make it, is because the school was really poor at supplying materials, so a lot of little remnants left from this and that gave me the materials to make the little parts:)
I don't mean to step on anyone's toes, but over the years I've always been one to think outside the box, and never accept "because this is way we've done it for XX years" as a logical answer. Technology and materials advance, and there isn't any reason not to look into them. My concern comes from the fact that we're powering a cast iron or steel cylinder with moist steam. Do as you may, but you won't get all the water out of the ring grooves without taking the cylinders apart after each run, and it *will* rust. The grit and scale from this rust will then slide back and forth and eat up everything over time. It's my opinion that a bronze piston, stainless cylinder, and Teflon rings arranged such that the piston never contacts the cylinder, would provide very low maintenance, no corrosion, and long life. 2nd choice would be bronze on bronze, with Teflon rings. If you like the look and rigidity of castings, they can always be lined. This is especially important to me, because IF I ever build a steamer, it will see regular use, and to make sense for me to have and operate, will need to be able to quickly build steam, and quickly/easily be drained/fogged/lubricated after use. Otherwise, it doesn't make sense to have it.
It's like my boat in a way, I have everything equipped with petcock valves and easily removable end-caps on the cooler so I can quickly drain and winterize my engine in about 15 minutes. There are "windows" for it's use defined by the amount of daylight, tides, when the fish like to bite, and when I have time to go, that I am able to make, because I can quickly "ready up" my boat, use it, and "put it back to sleep" afterwards. If I had to spend 2+ hours reaching in under the engine blindly threading in and out pipe plugs into holes with grit in the threads, like it was originally, I would lose many opportunities to use the boat.

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Re: steam engine need help!

Post by 10KPete » Wed Dec 27, 2017 1:45 pm

Steam engines are run with steam oil that is selected for it's ability to, among other things, stick to metal. Cast iron quickly develops a 'seasoning', like a cast iron frying pan, that I swear is water proof.

Now, my experience is with marine engines but I suspect the same is true of any cast iron part.

If the cylinders, and other devices, are cycled thru while still hot they will very quickly dry. But if just left wet they can start to rust pretty fast.

The only rust I've seen was the result of not enough oil, wrong oil, or neglect after running.

Marine installations are very picky as many condense the exhaust into the hot well and is then fed back to the boiler. But any bit of oil in the boiler is a major problem and great effort is put into oil separation.

Locomotives just blow the exhaust out so oil can be applied in excess with out damage.

Just tryin'

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Re: steam engine need help!

Post by Harold_V » Thu Dec 28, 2017 4:07 am

rkcarguy wrote:Harold, research shows that many manufacturers "formula's" of PTFE have a temperature rating to 400*+.
Yep! I've used that very material for a seal in a tilting reverberatory furnace I built when I was refining precious metals. The trunnion served double duty, both as a trunnion and a tuyere. The furnace was operated long enough to require relining two times, with not a single issue with the seal, which was an O ring. It was kept marginally cool by the air/fuel (natural gas) being introduced. Operating temperature of the furnace was right at 2,000° F.

Here's a picture of the furnace:
Tilt furnace #1.jpg
Wise people talk because they have something to say. Fools talk because they have to say something.

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