Grinding Piston Ring Gap

[Malcolm BeggParticipant @malcolmbegg82759]

Apologies if this has been discussed here before, I am doing up a Norton Dominator and have ground the gap on piston rings on the Myford lathe ,if anyone is interested on how it was done, let me know and I will do another post with details.

[Malcolm BeggParticipant @malcolmbegg82759]

How I ground the Gap on the myford.

[Michael GilliganParticipant @michaelgilligan61133]

Yes please, Malcolm

… always happy to learn new tricks.

MichaelG.

[LathejackParticipant @lathejack]

Yes Malcolm, that would be appreciated. I made this batch of new piston rings for a flat twin stationary engine a while ago, four compression rings and four oil control rings for 56.5mm bores. I have heat treated them but have still not gapped them because I was waiting for a better method than just filing them, so your method could be just what I've waited for.

[Malcolm BeggParticipant @malcolmbegg82759]

Hi

As you have shown interest, I will now add photos and explain what to do,all you need is a small grinding wheel with a spindle to fit in the lathe chuck,the width of the wheel has to be less than the gap in the rings,next find two pieces of plastic or plywood slightly larger than the rings,I made mine out of plastic as I have odd cuttings from my sign making,they do not have to be round so long as they cover the piston rings,these are used to clamp the ring,you then have to bore a hole in the centre of the plasic/ply the same size as the tool holder spindle and cut a notch out slightly larger than the ring gap.

Before you try to grind your rings you have to determine how much is needing to be removed,there is a couple of ways you can do this,I put the rings in the cylinder about 12mm / 1/2"down and found that they overlapped,you can measure the overlap with a feeler guage,or do what I did and ground enough off so that they would go into the cylinder without overlapping,you can then get a feller guage in the gap,you then know how much to take off.

Remove the toolholder clamp,slide your fist piece of plastic/ply over the spindle,ensuring that the gap is away from you,set your ring in,put the other piece of pastic/ply on top,again have the gap away from you,put your toolhoder clamp back on and tighten,put the grinding wheel in the lathe,offer it up so that the wheel is sitting in the gap, you can then remove so much from either side of the ring by first moving the the toolholder forward

and then reverse,I think it was a 10 thou gap for the Norton,5 thou off both faces.

I hope this helps,it worked fine for me and you know it is accurate,and the good thing is, it will cost you next to nothing,unless you have to go and buy a lathe!!

If there is anything you are not sure of don't hesitate to get back ,and I will see if I can get it explained a bit better.

I think if you look at the photos you will find it is self explanatory.

I will put the photos in another post as I do not want to lose all this work

Thanks

Malcolm

Edited By Malcolm Begg on 14/04/2015 11:29:02

[Malcolm BeggParticipant @malcolmbegg82759]

Here are the photos!

[Malcolm BeggParticipant @malcolmbegg82759]

If anyone out there has any other/better ideas on how to grind piston ring gaps on a lathe I would be glad to hear them.

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