Making poppet valves on a Bridgeport mill.

[jpeter]

Want to see me making valves for the v8 you see in my header, check the youtube link. BTW, they're 5/16 Dia. from drill rod. I think 12L14 would have been a better choice. Anybody had experience using valves made from 12L14?
[ame]http://www.youtube.com/watch?v=47tx15FgLQ8[/ame]

 

[lee9966]

Nice work. I need to be more creative like that with my CNC mill, thanks for the great idea


Lee

 

[gbritnell]

Jim,
I would never make valves from 12L. At the least little sign of moisture 12L starts to rust. My choice is drill rod or 303 stainless steel.
By the way that is the nicest cutting drill rod I've ever seen. Usually without running coolant on drill rod you get a nice purple chip coming from it.
Might I ask why you made your stems .125 diameter? Even .094 should be substantial enough.
gbritnell

 

[jpeter]

Your right, I did have that tool cutting well. Why did I make the stems 1/8, I don't know. I never thought about doing anything differently. I hold them on with c-clips but I could use smaller ones. Maybe on my next project I will try a smaller stem. Thanks for the idea.

 

[putputman]

George, this question is for you. I have seen some of your engines and they run just beautifully so I am thinking you have a particular reason for going to .094 rather than .125 diameter on the valve stems. Do you have a secret that you are not sharing with us? ??? ;D

 

[stevehuckss396]

George, this question is for you. I have seen some of your engines and they run just beautifully so I am thinking you have a particular reason for going to .094 rather than .125 diameter on the valve stems. Do you have a secret that you are not sharing with us? ??? ;D

I dont think there is a secret. I think it's just a matter of the less stem you have, the better the air/fuel flow.

 

[Lakc]

You can use 1/8 stems and undercut them just above the head like their full size counterparts. I just checked the last ones I made, and the stem drops to ~.100 on the intake valves, all done by eye, no undercut on the exhaust.

For all the poor heat transfer of steel, the only place the valve can shed its heat is the stem or the seat, and the seat surface area is barely anything compared to the stem surface area.

I am waiting for someone to show me how to hollow them out and fill them with sodium.

 

[gbritnell]

I have just always made them somewhat proportional to their full sized counterparts, plus a little. My 4 cylinder OHV engine has .078 diameter valves as well as the V-twin. The heads on the V-twin are .405 diameter so I just make a bigger radius to support it. This gives a nice curvature for the air flow into the combustion chamber. I don't think there's any hard/fast rule for the diameters, it's just something I've always done. I've never had a problem with the valves distorting or sealing.
gbritnell

 

[reubenT]

Ahh! finally found someone making their own poppet valves. I have an idea of making my own balanced poppet valves for a decent size steam engine to handle high pressure of a water tube boiler, seems to be the best type for the job. The first project is converting an IC engine, but if I have problems with water condensate in the oil I may build the whole thing from scratch eventually to get one without an oil sump. The valve body can be a simple casting as part of the cy head, but I've been looking for how to make the valves and no steam engine designer or maker on 3 forums has yet had an answer. Drill rod. I'm looking at grade descriptions and; which grade would work best? hardened after shaping or not? Thanks. RT


PS; doing some more looking it looks like W1 is recommended for most general purposes. good for valves too?

 

[stevehuckss396]

Ahh! finally found someone making their own poppet valves. I have an idea of making my own balanced poppet valves for a decent size steam engine to handle high pressure of a water tube boiler, seems to be the best type for the job. The first project is converting an IC engine, but if I have problems with water condensate in the oil I may build the whole thing from scratch eventually to get one without an oil sump. The valve body can be a simple casting as part of the cy head, but I've been looking for how to make the valves and no steam engine designer or maker on 3 forums has yet had an answer. Drill rod. I'm looking at grade descriptions and; which grade would work best? hardened after shaping or not? Thanks. RT


PS; doing some more looking it looks like W1 is recommended for most general purposes. good for valves too?

I usually use O1 drill rod for no reason other than it works great for me.

 

[jpeter]

Like Steve, I use drill rod for IC engines mostly because its handy but for steam I'm not sure. I might choose brass cuz the pressure's not too high, the heat's not too high and avoiding rust would be a top priority. Heck, maybe aluminum would work. Cast iron might be good too.

I made valves in the bridgeport because I needed a lot of them. They were for the v8 in my avatar. I'm not sure I used them. I think I wasn't all that pleased with the results. It's been a while.

 

[reubenT]

Ok thanks. maybe it's not too critical what I use, it does need to be hard enough to take a pounding on the seat, but an old D4 cat engine I rebuilt had valve seats machined in the cast head, so I guess that works fine for low rpm engines. I'd cut the seats in the valve body casting and then have a double disc valve, one disc a little smaller than the other. I don't think aluminum would work long term. cast iron might, but drill rod makes more sense. temp would be just under 500 F at 600 psi steam. Rust probably won't be an issue as long as it's not the type that rusts super fast. Of course we make em on whatever machine we have that'll do it, I have an FE Reed lathe,originally made for a line shaft shop. I put a 6 jaw precision adjustable chuck on it, the original was cracked and worthless. RT

 

[Harold Lee]

Want to see me making valves for the v8 you see in my header, check the youtube link. BTW, they're 5/16 Dia. from drill rod. I think 12L14 would have been a better choice. Anybody had experience using valves made from 12L14?
>>> SNIP <<<<

Jim - I have always used 12L14 to make my valves and have never had any issues. BUT (!!!!) All of the engines I have built have been low RPM, low performance hit & miss type engines. I have even made a cam gear for and odd & ends engine from black delrin. If I was making some of the engines that some of the folks are building here, I would use a harder material and in some cases I might even harden and then grind like the big guys do. Much of it depends on what you are wanting to do IMHO...

Harold

 

[jpeter]

12l14 does machine really nicely and I'm sure its strong enough for valves but as some have mentioned it rusts quickly. I know it does in my shop while the drill rod stays shinny. In IC engines I don't think valves pound the seat too hard. They do get lowered by the cam. I'm not too sure about what happens in steam engines. The v8 in the avatar has aluminum seats. I've run several gallons of fuel through it without valve issues but I do try to not let it get too hot. If I worked it hard the seats might not hold up.

Did you see George B.'s procedure for making valves. If you haven't you ought to.