Author Topic: A new attempt at making piston rings  (Read 2640 times)

Online Brian Rupnow

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Re: A new attempt at making piston rings
« Reply #15 on: April 22, 2021, 01:48:36 AM »
And here we have a quick and nasty round ceramic file (220 grit emery paper glued around a turned broom handle), and my rings are all deburred on the inside/edges. Tomorrow I will break them in a vice, file the ends, try them for size in a cylinder, and then heat treat them.

Online Roger B

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Re: A new attempt at making piston rings
« Reply #16 on: April 22, 2021, 08:58:26 AM »
Looking good so far  :ThumbsUp:

How were you measuring the 0.62" ring groove? If the grooving tool measures 0.62" and enters the groove it must be at least 0.62". Feeler gauges might give a better answer.

I have found that the better the finish inside the ring the less likely they are to break when fitting.
Best regards

Roger

Online Brian Rupnow

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Re: A new attempt at making piston rings
« Reply #17 on: April 22, 2021, 03:42:50 PM »
The rings have all been split. This is a very simple procedure where part of the ring is clamped in the vice and one half sticks out the end of the vice where it can be grabbed by my finger and them and gently pushed back and forth until it cracks. You have to be careful with your pushing and pulling, as you don't want to snap the ring in two pieces. At this point in the game, the rings are still the same i.d. and o.d. as they were when machined.

« Last Edit: April 22, 2021, 03:49:45 PM by Brian Rupnow »

Offline simplyloco

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Re: A new attempt at making piston rings
« Reply #18 on: April 22, 2021, 04:26:52 PM »
Hi Brian. The military taught me how to make (and break) piston rings. Take a crosscut chisel, place the ring on a round bar firmly held in the vice, place the chisel at 45 degrees on the ring and whack it! Never broke one ever... :LittleAngel:
John

Online Roger B

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Re: A new attempt at making piston rings
« Reply #19 on: April 22, 2021, 05:31:26 PM »
I now split mine with piano (music) wire side cutters.
Best regards

Roger

Online Brian Rupnow

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Re: A new attempt at making piston rings
« Reply #20 on: April 22, 2021, 06:53:37 PM »
I have made a heat treat fixture on which to mount the rings. Trial and error showed me that making the inside diameter of the fixture 0.942" diameter and forcing the rings over it resulted in a 1/8" gap between the ends of the ring. I truly felt that if I spread the rings any wider they were going to break. The rings are tightly compressed between the two discs to keep the broken ends of the rings perfectly in line. The back-side of the fixture has been hollowed out so it will have less mass to heat up. I will heat fixture and rings to a cherry red with my oxy acetylene torch, being sure not to let the torch flame play directly on the rings. The ring ends will be filed after the heat treat is finished and the rings demounted.

Online crueby

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Re: A new attempt at making piston rings
« Reply #21 on: April 22, 2021, 07:42:28 PM »
What is the purpose of spreading the rings on the fixture? I know very little about how IC rings work.

Online Roger B

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Re: A new attempt at making piston rings
« Reply #22 on: April 22, 2021, 08:05:03 PM »
The idea is to open up the gap and then use the heat treatment to 'lock' this in so that when the rings are compressed back to their nominal size there is a pressure against the cylinder wall to start the sealing process. The gas pressure behind the rings then increases the sealing force.
Best regards

Roger

Offline gbritnell

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Re: A new attempt at making piston rings
« Reply #23 on: April 22, 2021, 08:06:26 PM »
Brian,
I'm not sure about your method of expanding the rings! It seems like you'll be changing the whole diameter. The Trimble fixture is calculated to expand the ring to maintain the proper diameter.
Talent unshared is talent wasted.

Online crueby

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Re: A new attempt at making piston rings
« Reply #24 on: April 22, 2021, 08:11:28 PM »
The idea is to open up the gap and then use the heat treatment to 'lock' this in so that when the rings are compressed back to their nominal size there is a pressure against the cylinder wall to start the sealing process. The gas pressure behind the rings then increases the sealing force.
Ah - gotcha - thanks!

Online Brian Rupnow

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Re: A new attempt at making piston rings
« Reply #25 on: April 22, 2021, 08:17:27 PM »
After being heated cherry red, and left to air cool, then a little bit of clean-up, the rings have all taken a new "set" and the gaps remain open about 1/8" after they are removed from the fixture. I have seen on Youtube where some people heat the rings to cherry red, then drop them into a bucket of oil or water while they are still cherry red. I have no idea why they do that, and I've never read anything saying that this is a part of the process. My next step will be to square up the broken ends and test fit them into a cylinder to check that I have about 0.004" gap between the ring ends.

Offline Don1966

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Re: A new attempt at making piston rings
« Reply #26 on: April 22, 2021, 09:21:28 PM »
You may find this useful.... http://www.jerry-howell.com/PistonRings.html


Don

Online Brian Rupnow

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Re: A new attempt at making piston rings
« Reply #27 on: April 22, 2021, 09:34:39 PM »
The six rings are finished and properly gapped to 0.004" when installed squarely into the cylinder. As far as I can tell, I've made six good rings.---A funny thing about cast iron---it grows when it's heated, and when it cools off, it doesn't return to the dimension it was before. It is always a bit larger, even after it cools down. I knew about this from a previous experiment and I know that the two stroke airplane engine crowd will sometimes heat up a piston to "grow it a little" if they aren't running tight enough to get good compression. It shows up here because after these rings were split they would still fit down into the 1" cylinder bore perfectly. After being heat treated, before having the ring gap filed, they would no longer fit into the cylinder. I expected that, but it's still kind of surprising.

Online Brian Rupnow

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Re: A new attempt at making piston rings
« Reply #28 on: April 22, 2021, 09:48:51 PM »
Brian,
I'm not sure about your method of expanding the rings! It seems like you'll be changing the whole diameter. The Trimble fixture is calculated to expand the ring to maintain the proper diameter.
George--I'm not 100% sure of it either, but it seems to have worked very well. I'll know for sure after I get a piston made and try them out. When I done this kind of thing ten years ago and wedged the gap open with a piece of plate and then heated the rings one at a time until they dropped off the plate it didn't work. the rings I made were definitely not round after that process.

Online Brian Rupnow

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Re: A new attempt at making piston rings
« Reply #29 on: April 22, 2021, 09:52:17 PM »
This is the side shaft hit and miss engine that I will be trying these rings on. It runs like a charm with the single Viton ring on the piston. I'll know after I make a new piston and put a couple of these new rings on it how successful I was at ring making.