Author Topic: Rays Latest Engine - AKA Alyn Foundry RLE  (Read 865 times)

Online Jasonb

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Re: Rays Latest Engine - AKA Alyn Foundry RLE
« Reply #15 on: August 01, 2020, 10:25:02 AM »
I wonder if you would have had more luck using a bit of CI bar, with that many failing it may have been the iron or a slight flaw in it. Viton should work well and you could probably get away with one which should allow for longer coasting between hits.

Offline RayW

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Re: Rays Latest Engine - AKA Alyn Foundry RLE
« Reply #16 on: August 01, 2020, 04:48:55 PM »
Hi Jason,
The material was fine and machined nicely..
I think it was the width of the rings ( 1/8" as per plan)  that made them too inflexible. There was no groove depth shown on the plan and I scaled it at 3/32", resulting in quite chunky rings.
I did manage to get one into the first ring groove by feeding it in spirally, but there was no way a second ring would have gone past that into the second groove. Even though the rings all fitted in to the cylinder with a couple of thou gap, and the internal diameter was slightly larger than the diameter of the ring groove, I simply could not get the piston into the cylinder even with just the one ring fitted. I can only assume that the ring was not sitting right down in the groove for some reason.
As a point of interest, the ring grooves on the Robinson were only half the width, at 1/16"
After several attempts at fitting/removing rings, as I said in my previous post, I decided to go for Viton rings, which I have now fitted, and which already appear to be giving good compression.
Ray

Offline Alyn Foundry

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Re: Rays Latest Engine - AKA Alyn Foundry RLE
« Reply #17 on: August 01, 2020, 07:05:31 PM »
Hi Ray.

The piston casting was a " Buckley " grade M, quite soft so I'm not surprised they broke. Sadly I never got round to amending the notes on construction.

For all my piston rings made these days I use a simple 90/1000" square form with a 95/1000" deep groove.

However....

Viton is now the material of choice for us.

Cheers Graham.