Twin Cylinder Steam Engine

This past weekend was a little productive, got the oak base glued up and trimmed out, the flywheels are done, and got the eccentric cams machined, not shown in this picture.
Need to check around the shop for more material to keep going.
Thanks for your interest
Pat
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Moving along, got the pistons, piston rings, con-rods made and fitted the components to the cylinders. So far all is well
Thanks again
Patrick

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That all looks nice, what did you make the rings out of.
 
When I was making steam engines we packed the rings with gland packing, a string stuff embedded with graphite. I have also made them from mehanite iron. I'm not sure what it really is....(Google it)

"The Meehanite process which when followed will produce, according to Meehanite, cast iron with uniform soundness, consistent physical and mechanical properties and dependable performance in service." Courtesy Wikipedia.

There you go, a truly uniform iron.
 
Thanks, In one pic they looked like normal steel, and in another they looked more like the ones the I use in normal engines. I was thinking something like a good plastic or something might make a good seal on the pistons. The few steam engines I have done had no rings and had a bunch blow by.
 
Piston rings are normally made of cast iron, Meehanite being one type of cast iron. It doesn't matter whether it be gas engines or steam or diesel, they are usually made of cast iron. The high percentage of graphite in the iron helps with lubrication, especially when used with cast iron cylinders. Plastic rings probably would disintegrate in short order, the temperatures are elevated by the steam in the first place, plus the added heat of friction would cause the plastic rings to melt at the ring face where it meets the cylinder wall. Plastic rings might work for a short time if the engine is run only using compressed air, but steam would probably not work very well at all.

Graphited string packing, as mentioned earlier, works well in small steam engines, but once you start getting into cylinder bores of about one inch or more, the string packing just does not work too well.

Some individuals have had good luck using neoprene O-rings for compressed air engines, but Viton O-rings seem to work much better, especially if running on steam. When using O-rings it is important to remember that the o-ring does not need to be 'squeezed' into the bore, it should not fit overly tight.

Regardless of what material you are using for rings, it is important to remember that you do not need the high ring pressures with steam or compressed air that we are used to seeing with internal combustion engines. The rings merely need to seat and close the gap all the way around the piston, but do not need to exert the sealing pressure that is typically used with gasoline engines. I read a very interesting article on this somewhere, though I do not remember where. If I can find it I will post a link to it if it is available online.
 
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Not trying to hijack the thread here, but merely offering pertinent information on a sub topic of this engine build. I found the article I was thinking about, and it can be read on Jerry Howell's web site. The article discusses wall pressures exerted by the ring on the cylinder wall and also discusses some methods for making your own rings. Here it is for those who might be interested: http://jerry-howell.com/PistonRings.html
 
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Terry, thanks, that's good input on the rings. Bob
 
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