A new attempt at making piston rings

[Jasonb]

Conventional wisdom?
I guess that I don't have any of that. Good luck with your rings.

Dave

Don't worry Dave, as I posted on HMEM Trimble obviously did not either when he described how to gap the rings AFTER heat treat which Brian seems to have totally missed as well as finish turning to width

[Twizseven]

Brian,

What is your final gap be after the ring has been fitted in the bore.  Are you working to the typical 4 thou per inch of bore diameter?

Colin

[Brian Rupnow]

The 0.004" gap is put in the ring before it is heat treated. The larger "operating gap" of 0.150 is put in during the heat treating stage.
Ladies and Gentlemen--I have a thrilling announcement to make. My engine runs with my own home brewed cast iron rings. This is the first time ever for me to successfully make my own cast iron rings to run in one of my engines. I followed about 80% of the Trimble method of making rings. This makes me feel very good.---Happy Dance-Happy Dance!!!!----Brian
<a href="https://www.youtube.com/watch?v=cupLhD2bC3I" target="_blank">http://www.youtube.com/watch?v=cupLhD2bC3I</a>

[Vixen]

Well done Brian,

I am pleased you got the result you wanted, despite all the rude and offensive comments from one person on both this and the HMEM forum.

Mike

[Brian Rupnow]

So, what are my opinions of the Trimble method of making rings? I made the fixture Trimble used for "cleaving" the rings. It works fine, and I will use it because I now have it---But really, I don't think it does a better job of breaking the rings than just pinching the rings in a vice and breaking them with your fingers.
-----The expanding mandrel that Trimble mounts his rings on to machine the side of the ring which wasn't deburred and chamfered before it was parted off from the parent stock.--I didn't feel that it held the ring securely enough to machine the face of the ring, but it did hold the ring securely enough to get in there with a piece of emery paper and do a good polish and chamfer the exposed side of the ring.
-----The heat treat fixture worked really well, because it kept the rings clamped together during the heat treat cycle so they wouldn't twist and deform like they often do when hanging them from a spreader pin or plate and then heating them until they drop off.
----There has been a lot of discussion about how much heat to use on the rings to get them thoroughly heat treated. I bought a small heat treat oven to do this, so I could come up with a repeatable process. I heated the fixture and rings for 3 hours at 1100F and that seems to have done the job very well.
-----When I make rings in the future, I will use this method for making the rings. Also, in future, I will make the rings 0.045" wide, same as Trimble did. (for a 1" diameter piston). I made the rings .038" wide x 0.038" deep because that is a millimeter, which is a standard unit here in Canada. On my next set of 1" dia. rings, my rings will be 0.045" wide x 0.038" radial thickness.
----Thank you all for following my posts, and thanks to those who provided some guidance to me.-------------Brian

[Kim]

Congratulations Brian!
Glad to see you got it to work!  You showed a lot of persistence in this effort.   

Now that you've proven you can do it, are you going to go back and look at some of your earlier attempts to see what the differences are?  Do a little post-analysis?  Or just go fward and be happy!

Great work, Brian,
Kim

[Jasonb]

Good to see they worked out for  you in the end Brian

Whether they would have done without me and a few others correcting your wrong interpretations of the Trimble method who knows but I feel its better to offer a point in the right direction that just sit quietly by and just comment at the end.

[crueby]

Great to get it figured out, and to well document the Trimble-Rupnow process!   

[Twizseven]

Well done Brian, bit of a struggle but you got there in the end and had the result you wanted, a working engine.

Regards,

Colin

[petertha]

Also, in future, I will make the rings 0.045" wide, same as Trimble did. (for a 1" diameter piston). I made the rings .038" wide x 0.038" deep because that is a millimeter, which is a standard unit here in Canada. On my next set of 1" dia. rings, my rings will be 0.045" wide x 0.038" radial thickness.

I guess I don't really understand this reasoning, but as I mentioned on HMEM, I'm very glad you have a firing engine, so big congratulations.

1mm = 0.0394" so if you mean a 1mm tool just so happens to result in a ~0.001" clearance to a 0.038" wide ring you chose, I suppose that is a convenience consideration. But what does a so called standard unit in Canada have to do with anything? If its an insert tool, its very likely of offshore origin and nominal thickness. Parting tool inserts come in many width flavors. Grooving tools come in other flavors (often designed around metric circlips or O-rings or whatever). Also just because a tool has a catalog defined width doesn't mean they obey the (tight) tolerance that piston ring fitting requires. Some inserts state a tolerance & others you can measure +/- 0.001 variation across a batch of inserts from the same box. For example a nominal 1mm wide tool that happens to be 0.001" undersize = 0.0384" = 0.0004" clearance on 0.0380" ring (not enough).

There is nothing dictating you have to achieve the finished groove width by a single cutter plunge, that was your preference. Alternatively you can cut on either side of the ring groove face with a thinner tool & completely remove the issue of matching a tool width to a ring width or visa-versa. If you are grinding a HSS to to match you have full control, but again the tool width & ring width is a chicken & egg thing and mm doesn't really factor.

Then regarding the groove depth issue, this is of course 100% controlled by your lathe in-feed & measurement, so nominal/standard mm is a non-issue. You mentioned you would make the rings wider next time, more aligned to the Trimble sizing and that is all I'm trying to clarify. His procedure is: Step-1 determine the appropriate ring width for the constraint reasons he outlined & shown on his graph. Step-2 is factor the desired clearance behind the ring. That yields the target diameter of the piston groove, by whatever choice of tools works to achieve that dimension.

[Brian Rupnow]

This post is not so much about rings, but it does show something very important. I am always amazed at how much a difference in gas tank height affects an engine. When I built this engine a few years ago, I had made a gas tank to fit underneath the cylinder, with a 3/32" diameter check valve in the discharge. This year when I went to start it, I couldn't get it to draw fuel up from the tank. Okay, when these engines set around on the shelf for years, check valves have a tendency to freeze up. That wasn't a big deal, I just grabbed a spare gas tank I had and mounted it on a block of wood. This allowed me to start the engine and see that it actually did run. After putting the cast iron rings in, the engine would run good for four or five minutes and then die, as if it were running out of fuel. When everything else is set at "optimum" and the engine dies for no good reason, I always suspect the gas tank height. In this picture you see a 1.6" tall aluminum spacer under the tank. That fixed it!! Now the engine will run until I turn it off with the switch in the electrical system.

[MJM460]

Well done Brian, your persistence has paid off.  And I am sure it will serve you well for future builds.

Regarding the fuel tank height, I guess the carburettor throat only produces so much suction.  Of the tank level is low, there will be less fuel flow until eventually insufficient to run the engine.

But of course, with a high level, there is a danger of the fuel continuing to flow when the engine stops, hence the float valve in the traditional automotive carburettor.  Perhaps a chicken feeder style, with the level just below the carburettor is called for.

I have followed your journey on the rings and endured the pain with you as each step forward seemed to be accompanied by a step back.

MJM460

[Art K]

Brian,
Happy dance is right, who hooo....great to hear it running.
Art

[Roger B]

The power of persistance     

Do you have any thoughts on which steps in the new ring making process made the improvement over your previous attempts?

[Brian Rupnow]

I think that having the correct heat treat fixture and the oven were the two biggest factors. I don't really think that the fancy "cleaving fixture" did a better job than clamping the ring in a vice and snapping it with your fingers. I think some credit has to be given to the expanding mandrel fixture, which lets you mount the ring and really clean up and chamfer the sides of the ring.---Brian