Making an Engine Valve out of Steel

[Bluzzin]

Hello All,

I am getting back in to model engine building after a 5 year break while life got in the way. I have built a few steam (air) engines, a die filer and other assorted beginner projects with success.

I am picking up where I left off which is building Rudy's Pioneer Engine and I am stumped on the valve which are steel, .500" diameter head, .125" stem, 2.060" overall length. My problem is how to turn it , that small a diameter, that short of a distance I don't really have room to take advantage of a follow rest. The only answer I can come up with is to make the valve head and then press fit the stem into it, using drill rod for the shaft.

Any ideas or insight would be appreciated.
Thank you
Bluzzin

 

[Brian Rupnow]

I wouldn't recomend a two peice valve. I put some advice about valve building in my Atkinson thread, but I will repeat it here. Chuck up a peice of steel slightly larger than 1/2", with just enough protruding from the chuck jaws to make the full length of the valve plus about 1/4". Turn the o.d. to 0.5" to within 1/16 of the jaws. This will acount for any eccentricity (run out) in the chuck. Then starting at the end farthest from the chuck, turn to within .005 of finished diameter, but only do it to 1/4" of the length. Record where you stop (by the crossfeed dial or with a crossfeed stop). Then back out and do the next 1/4" of length. By doing it this way, you always have the full 1/2" diameter between the cutter and the chuck, so you will get very little deflection. When you reach the point where the stem flares out to a larger diameter, use a very sharp HSS cutting tool and take down the final .005" over the full length up to the flare. then swing your crossfeed around to the requires angle and cut the angled face out to the full diameter. Then part it off from the main stock.--(Thats why you left +1/4" out beyond the chuck jaws.)

 

[Bluzzin]

Brian, Thank you. I will try your method and read your Atkinson thread.

cheers
Bluzzin