Piston ring articles in ME: 4350 vs 4450

These articles by Alan Beasley and John Dickinson describe very different methods. The former turns to size, breaks, pegs open and heat treats. The latter turns to slightly over size, cuts through, squeezes together and clamps, and turns to size; no heat treatment. Both are rings for steam engines, not i.c. engines. I would be very interested in opinions and comments on these different methods, especially from experienced builders. I need to make rings for "Doncaster" which has 1.75" pistons.

I have made rings using the former method t, turning to size breaking, pegging then heat treating for a Doncaster and also for several IC engines. It is an easy method.

There is no real difference in the final product. More spring, so a larger ‘spring’ gap required for ICE use and a larger clearance gap required when fitted, I expect.

As Bob says, the former is the easier method. Usually spring the ring on a metal strip of the required spring gap and heat until the ring falls off.

Not so easy the way he did it. He made jigs for each ring size which both pegged them open and clamped them flat while heating to, I think 600, for a defined period.

Chap called Trimble also described the "Pinning open" method in ME 3735. I have used this method for three locos now, all with different sized pistons, with excellent results. I recall moving my 5"G Edward Thomas in the workshop a while ago when I was cleaning it. Some time went by and I had cause to move the reverser. There was an audible chuff - it had held pressure for quite some time.

I didn't use Trimble's brown paper idea; I simply coated my rings inside the fixture with Easyflo flux and held the whole doings at a very dull red heat for a few minutes.