Nick,

For my last set of wheels (about 4 1/2" diameter), I used tungsten for the backs and the tips were fine – no problem when 'breaking through' but they did have a significant round nose and were the brazed tip style. The castings were very old and had significant hard patches on the front of the wheels but they were fine when I had to use a thin HSS tool for cutting the groove between the tyres and counter balance weights.

Phil H

Hi Nick, I've just finished turning the wheel castings for my next loco, in 1/2" scale they are 2&3/4" diameter and from Walsall Industries. They came with the solid back you have on yours, which I'd never encountered before. I used a carbide tipped tool and just took it steady when I thought I was close to breaking through. I noticed that as the cut became intermittent the sound changed. There were no problems, but I was a bit shocked when I realised how little allowance there was for thickness- I'd very nearly 'overshot the platform', as The Master used to say.

John.