> Hi, there is an artical in ME 4450 about piston rings a how to make them. Should be in the shops next Friday.

In my sweaty palms today!

Neil

I'v resently made half a dozen piston rings, the first four were for a petrol engine with a 2" bore, made of Meehanite, the same as one of the pistons, the other piston (have not tryed it yet) is aluminium), I cut the gap with a thinned junior hacksaw blade. The other two were made for a Stuart Turner S6 with a bore of 1.5", they were made from an old brake disk, to machine the outside diameter, I first bored the inner diameter, then glued it on a mandrel, the ring broke (in one place), on removal from the mandrel. All the rings were heat treated by wedging the gap open (1/4" I think),eating to red, and holding for a few miniutes, The Meehanite ones went on just like any small engine rings. The Stuart ones are fairly shallow, 1/8" wide x about 1/16" deep, and they are both in the one 1/4" ring groove, the rings being / seeming rather delicate, thought I'd have trouble, but no, they just popped on. They are all working OK, I only wish the petrol engine would work as well as its bits and piecesaybe one day! Ian S C

At our little museum we have an old Continental industrial engine, I think its about 3 1/2" bore, twin cylinder. when we got it, it had a broken piston ring, so I made one using the rim of a V pully, not much wall pressure, but it seems to work.

I made a small ring using window weight iron, even that didn't break, but I can't remember what it got used for. Ian S C

Iron should be OK if it came from Blackgates.

Thats quite a thick section ring for 1.5" bore, not really a loco man but is the 1/8×1/8 groove definately for rings and not packing, my similar bore traction engine uses 1/16×1/16 rings.

J

Dave, I am building a Sweet Pea, about 12 months behind you by the sound of it. I have experienced exactly the same problem as you posted. Very frustrating. How did you resolve the problem. Different material? different thickness. Very interested to find out.

Regards Les Brown

Tubal Cain did some experiments and calculations, he found ring pressures for rings specified for steam engines were almost universally excessive, greatly so.

Bear in mind that he was an authority on diesel engines, so he knew a thing or three about piston rings.

Neil

I have had mixed success with rings. Big ones no problem, small ones break. Easy solution is don't use metal rings, use graphite square section. I was sceptical about this but the results have been brilliant. Other option is find something that fits on ebay. You wont find them that thick but putting multiples together gives good results.

Rings must be expanded by the absolute minimum. To do this, cut three narrow strips of tinplate and make a right angled bend near one end of a short length. Arrange the strips aroung the piston then slide the ring down over them. When the ring is over the groove, remove the strips and the ring will spring into the groove.