Horizontal Air Cooled Engine

[Gordon]

I find it interesting that for something which is supposedly as precision as ring manufacturing that folks do it so many different ways. Heat for 1 hour, 3 hours, 4 hours. Use an enclosed tube and burn a piece of paper inside or use Brownell paste or just let them turn black and polish them. Seems like one person uses crude methods and the rings work just fine and the next person holds everything to +/- .0001 and they do not work. I have been going through the exercise again with my super frustrating Atkinson Differential and I have tried making rings several times and even bought rings from Dave Reed (Otto) and still cannot get enough compression.

 

[johwen]

Now Brian do you put a sleeve over the jig and wrap paper around the rings to remove the oxygen and prevent oxidation of the sealing surface of the rings? John

 

[Brian Rupnow]

No Johwen I do not. Anything that boils out of the fixture or the rings is easily removed with a brass bristled brush and dish soap.

 

[Brian Rupnow]

This is a picture of the rings on the heat treat fixture after 4 hours at 1100 degrees. The fixture and the rings look like crispy critters, but some scrubbing with a brass bristle brush and liquid dish soap cleans them up to a much better look.

 

[Brian Rupnow]

This is the rings after removal from the heat treat fixture. They will still require a bit of clean up, but they are essentially finished. Note that each ring has now taken a "set" to the 0.131" diameter of the drill between the ends of the rings. When compressed into the cylinder, that gap narrows down t 0.004", and that spring force is what keeps the ring tight against the cylinder sides.

 

[dsage]

SO now go the extra (simple) step and try Terry's light mask technique to see how well they fit in the cylinder. The extra few minutes is worth it.

 

[awake]

I find it interesting that for something which is supposedly as precision as ring manufacturing that folks do it so many different ways. Heat for 1 hour, 3 hours, 4 hours. Use an enclosed tube and burn a piece of paper inside or use Brownell paste or just let them turn black and polish them. Seems like one person uses crude methods and the rings work just fine and the next person holds everything to +/- .0001 and they do not work. I have been going through the exercise again with my super frustrating Atkinson Differential and I have tried making rings several times and even bought rings from Dave Reed (Otto) and still cannot get enough compression.

Yes, when it comes to rings, it often seems that one goes round and round in circles ...

But some people seem to be able to run rings around others ...

I was trying to come up with one more pun to round out the set, but I was afraid that someone might be as upset as if I'd pist on their cornflakes ...

Okay, I'm done now.

 

[CFLBob]

I find it interesting that for something which is supposedly as precision as ring manufacturing that folks do it so many different ways. Heat for 1 hour, 3 hours, 4 hours. Use an enclosed tube and burn a piece of paper inside or use Brownell paste or just let them turn black and polish them. Seems like one person uses crude methods and the rings work just fine and the next person holds everything to +/- .0001 and they do not work. I have been going through the exercise again with my super frustrating Atkinson Differential and I have tried making rings several times and even bought rings from Dave Reed (Otto) and still cannot get enough compression.

(bold added by me)

I've been noticing this, too. I haven't tried to make rings yet and this is one of those things that sticks my head. I bought Dave Reed's rings for my Webster and it ran for a few minutes a few times, then never again. Is it rings? Valve leakages? I just don't know.

The profession I retired from had a reputation for the same sort of things. Circuits wouldn't work or tune properly for one guy but another guy could make them work just fine. Can't tell you how many times I heard that it was "black magic." I thought it was pure physics, pure Maxwell's equations.

My interpretation was that there are little things that some people did and weren't aware of to put in their instructions or tutorials, or perhaps told themselves "everybody knows that" or "everybody does that." Maybe they were just better observers of what was going on. I suspect that the differences in rings is something like that. Little things that make a difference that people don't think of or don't realize they're doing.

 

[minh-thanh]

Hi CFLBob !

. Seems like one person uses crude methods and the rings work just fine and the next person holds everything to +/- .0001 and they do not work.

I've done a few ringless piston engines including 2 stroke and 4 stroke, and it runs pretty well,..so I think: The cylinder is the crucial and important part.
Just my thoughts - With me, finishing a cylinder well enough, rings only works to increase the tightness between the piston and the cylinder. If the cylinder isn't good enough, the rings can't "fill in" the cylinder's defect and that's not the ring's function !

 

[Gordon]

Hi CFLBob !

..so I think: The cylinder is the crucial and important part.
Just my thoughts -

So if that is the case, what is the best way to machine the cylinder? Boring bar, reamer, hone, lap.

 

[minh-thanh]

Gordon !
It is probably the best way !
I don't know how are you!? But making the cylinder can take hours, sometimes I have to redo it just because the cylinder is not really good
My first cylinder was aluminum, I chose aluminum because it's soft and easy machined and cheap but it took me a few months or more to make it good enough.
If the machines are good enough, the time for hone and lap will be less and back

 

[Brian Rupnow]

I think ring making is one of the dark arts. Sometimes everything works perfectly and my engines run with home made rings. Sometimes, using the very same material and same method they don't work. I have tried to take all guess work out of the machining and heat treating process and be methodical about making rings. I think that somewhere in the ring making process I have to go to a graveyard at midnight and kiss a black cats a$$ to make things work consistently.

 

[minh-thanh]

Hi Brian !

I think ring making is one of the dark arts. Sometimes everything works perfectly and my engines run with home made rings. Sometimes, using the very same material and same method they don't work. I have tried to take all guess work out of the machining and heat treating process and be methodical about making rings.

Why not look for other causes ? maybe another reason but it is not rings, the way you make rings or the materials .

I think ring making is one of the dark arts.
I think that somewhere in the ring making process I have to go to a graveyard at midnight and kiss a black cats a$$ to make things work consistently.

 

[Gordon]

Hi Brian !

Why not look for other causes ? maybe another reason but it is not rings, the way you make rings or the materials .

If it wasn't the rings or cylinder why will an engine run with O rings and not CI rings? If it was valves or gaskets etc it would not make a difference when using O rings.

 

[minh-thanh]

If it wasn't the rings or cylinder why will an engine run with O rings and not CI rings? If it was valves or gaskets etc it would not make a difference when using O rings.

Just my opinion, because I only made 2 pistons with O-rings, so I don't have much experience with it.
The O-ring is more flexible than a cast iron ring, so it easily increases the tightness between the cylinder and the piston - the high pressure in the cylinder will force the O-ring against the cylinder wall - and of course the same happens with the cast iron ring - but the O-ring will be easy to stretch to fit the cylinder's defect -
Example: an engine with a compression ratio of 7-1
If the ring is cast iron: Compression ratio is only 4 - 1
If O-ring : Compression ratio will be 6-1 or 7-1
Again : Just my thoughts !

 

[Brian Rupnow]

The viton o-rings give instant gratification. They seal 100 % immediately and take any notion of compression leaking past the rings out of the equation. I think they are just wonderful.--That being said, I want to learn to make and use cast iron rings consistently and accurately. I have tried to come up with an accurate and foolproof and repeatable method for making cast iron rings that work. I am very close. I have invested over $1000 for a heat treat furnace and controller, and read about a thousand pages of "how to" articles related to cast iron rings. There is a lot of conflicting information available, and some of it is absolutely wrong.

 

[minh-thanh]

There are a few different ways
Sometimes : Trial and Error - Try and be Patient !

 

[Brian Rupnow]

The only issue I have with grinding the outside diameter of the piston, is that once the piston stock has been removed from my lathes 3 jaw chuck, it will never go back in the same way. My chuck has about 0.003"total indicated runout. What that means is that getting the piston back into the chuck exactly as it was before depends solely on good luck. I'm not sure that would really affect the way the piston works or not. If I use an external lap to bring the piston down to size, it doesn't really matter if the piston is exactly centered in the chuck or not, because the external lap is free floating and is held in my hand.

 

[minh-thanh]

The only issue I have with grinding the outside diameter of the piston, is that once the piston stock has been removed from my lathes 3 jaw chuck, it will never go back in the same way. My chuck has about 0.003"total indicated runout. What that means is that getting the piston back into the chuck exactly as it was before depends solely on good luck. I'm not sure that would really affect the way the piston works or not. If I use an external lap to bring the piston down to size, it doesn't really matter if the piston is exactly centered in the chuck or not, because the external lap is free floating and is held in my hand.

Why don't you perfect the piston just once?!
I have read your thread about making an OD grinder, You can do an OD grinder when your lathe is correct, but if the lathe is correct there is no need to do an OD grinder
When I make the piston, I make the outside diameter of the piston bigger than the inside diameter of the cylinder And then I lapping until it can slide into the cylinder.
Then make a groove for the ring....
Lapping piston or cylinder: only slight pressure is required -
The abrasive compound will do its job
Don't apply too much pressure because compression and abrasive compound will deform your piston or cylinder

 

[Richard Hed]

I think ring making is one of the dark arts. Sometimes everything works perfectly and my engines run with home made rings. Sometimes, using the very same material and same method they don't work. I have tried to take all guess work out of the machining and heat treating process and be methodical about making rings. I think that somewhere in the ring making process I have to go to a graveyard at midnight and kiss a black cats a$$ to make things work consistently.

I've got a bunch of black cats. You can have allyou want.