slide valve material

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barts
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Re: slide valve material

Post by barts » Wed May 30, 2018 2:24 am

fredrosse wrote:I am considering placing a plate on the slide valve seating surface, about 1/4 inch thick, maybe stainless steel, and making the slide valve from filled Teflon. This would allow replacement of the simple flat plate (with some ports cut thru) with various materials, and no need to resurface the cylinder casting due to wear.

Has this arrangement been used with success? With other material combinations?

Thanks in advance for any information here.
I did this (a replaceable plate) on my refrigerator compressor conversion, since I made the steam chest from aluminum plate (surplus BFV armor :)). Personally, I think cast or ductile iron on the same is hard to beat for wear resistance, esp. when a bit of rust or boiler scale finds it way into the engine, but making the pieces replaceable w/o excessive work is a definite good plan. I used stainless + bronze on my little 2 x 2 conversion; every few years the slide valve needed some attention; the stainless piece was practically unmarked.
- Bart
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Bart Smaalders http://smaalders.net/barts Menlo Park, CA
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fredrosse
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Re: slide valve material

Post by fredrosse » Wed May 30, 2018 2:52 pm

Bart, what is: "surplus BFV armor :)"

Mike, what is: M.S.? "the ones I've made in M.S. with the intention of using gun-metal slides"
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Re: slide valve material

Post by Mike Rometer » Wed May 30, 2018 3:45 pm

fredrosse wrote:Bart, what is: "surplus BFV armor :)"

Mike, what is: M.S.? "the ones I've made in M.S. with the intention of using gun-metal slides"
Sorry Fred, common parlance in this neck of the woods! M.S. for mild steel. I should perhaps have said B.M.S. (bright mild steel).
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Re: slide valve material

Post by DetroiTug » Wed May 30, 2018 7:29 pm

Fred, The Tiny Power M that I had which I traded to Jon R (Jackie Lee), Had a plate that looked like high chromium tool steel inset in to the valve face and the slide valve itself had been machined and chrome plated. The plate was about 1/4" thick and and about as wide as the slide valve. It was secured with flathead machine screws set below the surface if I remember correctly. Seems like a good setup for condensing oil-less operation, although I never tested it for longevity. As long as you're using a steam cylinder oil, I think regular old gray cast iron is fine. My Locomobile engine is 117 years old and still has the original valves and the valve faces are not worn.

I was told by a very knowledgeable steam engine man that ductile/nodular iron should not be used for sliding surfaces. However, I've had others reply that they have used nodular iron for cylinders with good results, I would lean towards the gray cast only approach.

-Ron
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