Piston for Elmer's #29

[RCGUY]

I am getting ready to make the piston for my Elmer's #29. The cylinder is made of brass. Which would be better Aluminum or Brass for the piston?

http://www.homemodelenginemachinist.com/f31/first-engine-elmers-29-a-16286/

Ed

 

[portlandron]

From a chart I found years ago related to moving parts:
For brass: Excellent- Cast Iron, Nickel Iron & Drill Rod
Good - Nylon, Steel SAE 4140 H.T. & Teflon
Poor - Oilite, Steel SAE 1020 & 1040 & Stainless Steel
BAD - Aluminum, Brass & Bronze

 

[ProdEng]

According to the materials compatability chart I have, cast iron would be the best followed by steel. Any metal running on the same type generaly causes galling and I don't know why aluminium on brass is not reccomended. Hope that helps

 

[lensman57]

Hi,

I would be cautious as not to use a harder material as a piston in a soft cylinder. Replacing a piston is a lot easier than machining a new cylinder.

If you are going to operate the engine with steam then I would stay away from cast iron and steel, with compressed air there is no restriction on the material.

Good luck,

Regards,

A.G

 

[Brian Rupnow]

Use aluminum. I did , years ago on that same engine, and the engine still runs fine. The aluminum also gives you less reciprocating mass, which balances the engine much better.

 

[kvom]

X2 on aluminum

 

[RCGUY]

Thanks for all the information.

Since this engine will run on air to make sure it works. I decided to make the piston out of aluminum. The engine will end up being a display piece on a shelf.

Thanks again for the response,

Ed