Flathead hit and miss engine???

[Brian Rupnow]

This is something a little different, and I thought some might be interested in seeing it. I have reasons to make the cam and cam gear as two different parts, but they have to be rotationally locked together. There is no cam shaft--the gear and cam ride on a shoulder bolt.

 

[Brian Rupnow]

Sooner or later I'm going to need a gas tank and gas tank support. I've modelled them, but won't actually build them until after the engine runs. There is a days work in that gas tank and support, but first I want to see the engine running.

 

[Brian Rupnow]

Today was "working with brass day." All the carburetor parts are finished, but have yet to be assembled. I still have to make two brass spring retainers for my valves and two brass valve cages. I might make the lever which operates the exhaust valve from brass---it would look good but probably wouldn't stand up to the mechanism which operates off the governors to hold the exhaust valve open during the miss cycles. I have to think about that one for a while.

 

[Brian Rupnow]

Today I finished up my brass parts. I still have to solder a needle into the adjustment cap on the carburetor and press/loctite the valve cages into the manifold. Probably I will completely finish up tomorrow by assembling everything into the manifold.

 

[Brian Rupnow]

Today I almost made a valve-----

 

[Rdean33422]

I've made some of those too!

Ray

 

[Brian Rupnow]

On all of the i.c. engines I have ever made, I have turned the valves from a single piece of cold rolled steel. This works, but there is a difficulty. The valve stems are only 1/8" diameter. My lathe has a very wide saddle which makes it almost impossible to run a live center in the tailstock to support the end of the material which isn't in the chuck. The head of my valves is 3/8", but a stem of only 1/8" deflects away from the cutting tool. To avoid a lot of deflection I turn the valve down to size in three steps, each 1/3 the length of the finished stem length. This method works, but it is very butt clenching, because if you turn the stem undersize the valve is ruined so you have to start over. As my designs evolve, the stems keep getting longer and longer, and things get more and more difficult as you can see in the previous post. Tomorrow I think I will try a different approach. I will use 1/8" round cold rolled steel as the valve stem (which requires no machining). I will silver solder a piece of 3/8" cold rolled steel to the end of the stem, then turn it to the required angle. I haven't done this before, but if it works well for me, I may make any future valves two piece.

 

[JohnBDownunder]

That is the way I made my one and only valve so far Brian.
It was for an air powered Hit n Miss that ran really well.
Hitting and missing beautifully UNTIL I pulled it apart to paint it pretty.

Plans were from Brian Rupnow.
Here it is before painting, a bit of wobble in the flywheel tho.
John B

 

[Jasonb]

Should not be a problem Brian, your lathe is basically the same as mine yet all the engines I have made valves for I use the rotating tailstock ctr for support

Stem being turned 3mm dia

Spring retainer groove being cut

 

[Stefan-K]

On all of the i.c. engines I have ever made, I have turned the valves from a single piece of cold rolled steel. This works, but there is a difficulty. The valve stems are only 1/8" diameter. My lathe has a very wide saddle which makes it almost impossible to run a live center in the tailstock to support the end of the material which isn't in the chuck. The head of my valves is 3/8", but a stem of only 1/8" deflects away from the cutting tool. To avoid a lot of deflection I turn the valve down to size in three steps, each 1/3 the length of the finished stem length. This method works, but it is very butt clenching, because if you turn the stem undersize the valve is ruined so you have to start over. As my designs evolve, the stems keep getting longer and longer, and things get more and more difficult as you can see in the previous post. Tomorrow I think I will try a different approach. I will use 1/8" round cold rolled steel as the valve stem (which requires no machining). I will silver solder a piece of 3/8" cold rolled steel to the end of the stem, then turn it to the required angle. I haven't done this before, but if it works well for me, I may make any future valves two piece.

Brian
I would Encourage you to make a valve in two pieces. I always make my valves this way with good Results.
Give it a try.
Stefan

 

[Vietti]

I also favor two piece valves. Typically drill rod stems with ss heads. Silver solder together. Try it you might like it. Center drill the head end of the stem before soldering and then you can use a center when turning the head to shape esp the seating surface.

 

[Brian Rupnow]

I don't have a collet set up, so all turning of round stock is done with my lathes 3 jaw chuck. Like I said, my lathe has an extremely wide saddle. About the only time that causes an issue is when I'm making valves.

 

[Jasonb]

Same width as mine and I don't have a problem with 3 or 4 jaw either

If you feel you can't get the tailstock in to turn the stem you will have the same trying to support the head while you finish turn that

 

[Steamchick]

I have seen something like a valve head welded to the stem by friction welding. A small pip was left on the end of one part, the other flat. One piece held in the lathe chuck, the other part in the tailstock chuck or collet. Lathe run at high speed - 2000 rpm? - ish? As soon as the joint has pressure a plied the pip glows red, floor owed by adjacent metal, then tailstock wound into the part and the lathe stopped - quickly. The weld happens at the instant the lathe stops. The people doing this as a production process were very skilled with timing. Too slow = broken bits, and too fast = no weld - I think?
Must be a u-tube on the subject somewhere.....
K2

 

[Brian Rupnow]

After yesterdays total failure to make a decent valve, I persevered and made two valves today. I had almost convinced myself to try making a two piece valve, but chickened out at the last minute and made each valve from a single piece of cold rolled steel like I usually do. I picked thru my vast assortment of compression springs and found one 0.022" wire size for the exhaust valve which is cam driven, and an 0.015" wire size for the intake valve which is atmospheric. The valves were lapped into their seats using #420 aluminum oxide paste and then #600 aluminum oxide paste. I drilled and tapped the 3/8"-16 threads for carburetor and exhaust pipe into the manifold--this is something you can't really do until the valve cages have been pressed/loctited into the manifold and allowed to "set up" overnight. Everything seems to fit okay and I will polish the two brass top port plugs tomorrow before loctiting them into place. It's been a good day, and good wife went out to rescue a grandchild and has promised to bring me home some supper.

 

[Steamchick]

Excellent attitude and work Brian. Yet again, you have shown that when life serves up a pròblem, simple perseverance and calm attitude wins in the end.
As the guy who lost his dentures said, "If at first you don't suck seed, try,try again..".
Well done!
K2

 

[Brian Rupnow]

Today I would like to machine a gear. I also have to make a crankshaft, but I can start that after my gear is machined. I have to have both gears finished before I can drill and tap the crankcase for the second gear position. I could locate the second gear by just using computer generated math, but I'll feel better about it if I have both gears "in hand".

 

[Brian Rupnow]

I decided that since I had everything set up to cut one gear, I might as well cut the other gear as well. I then drilled and reamed a piece of scrap at the correct hole centers and inserted a pair of scrap stub shafts. The gears mesh just fine which makes me very happy. Now it's time for a coffee break and to decide whether I'm going to do any more today or not.

 

[Brian Rupnow]

Yesterday and today I finished machining the one piece crankshaft from 1144 stress proof and most of a piston from cast iron. Other than the usual butt clenching, the crankshaft machining went quite well. The piston doesn't have a hole for the piston pin, as I have decided that I have to do a modification to my rotary table before I do that. The bolts which hold my rotary table to the milling machine bed require that you must almost stand on your head and use a mirror to get them tightened, and I'm tired of doing that. I have a plan on how to fix that, and will do it now before I do any more engine parts.

 

[Brian Rupnow]

And for those who doubted---Yes, the crankshaft does fit into the crankcase thru the bearing holes. It is a very, very close thing, but it really does fit in there. Sometimes I don't even believe it myself until I actually have the parts in my hands to try it.