how to make steam throttle valve?

[crueby]

Getting close to finishing up my current engine project (3-cylinder steam, build thread in WIP forum), and want to include a throttle valve on it (small version of handwheel type valve). What is the best type that can be made from bar stock, without castings? At the size of a model engine, seems like it would not take much movement to go from 'off' to 'darn near full' with nothing in between. What type do they (you?) use on traction engines and such?
Did some searching, but did not turn up much, probably did not use the right keywords. Any pointers?

Thanks!

 

[MCRIPPPer]

i made a simple valve for my compressed air engine by drilling a block so that you end up with a hole going all the way through. tap one side of the hole for m5x.8(or whatever has a pretty small thread that you have) drill another hole that meets the cross drilled hole. make a tapered needle valve screw that goes into the hole and seals the non threaded part of the hole and keeps air from coming in and going out the other hole. use a shallow long taper for fine tuning ability, or use a 60 degree point if you want to be able to have full throttle at only 1/2 turn.

 

[abby]

A steam engine is controlled with a regulator not a throttle , for a railway engine 1/2 a turn from closed to fully open is quite usual .Some model engineers use a ball valve , some prefer needle type valves or even slide valves , if you search for steam regulator you will probably find a drawing or two.

 

[crueby]

Thanks guys!

 

[Charles Lamont]

Ideally you want something that will initially gradually open a tiny crack to demonstrate how slowly your engine will run smoothly, and then opens up something like exponentially to an area equivalent to the full bore of the steam pipe.

 

[crueby]

Ideally you want something that will initially gradually open a tiny crack to demonstrate how slowly your engine will run smoothly, and then opens up something like exponentially to an area equivalent to the full bore of the steam pipe.

Exactly - that is what I am looking for.