Machining Wheel Castings

[Nick Clarke 3Participant @nickclarke3]

Here are the front and back of a small wheel casting.

The back of the casting will need to be recessed to open up the spokes. Stan Bray in one of his books suggests that this used to be done like this in the past.

How much extra care do I need to take to avoid chipping the spokes as they come clear and the cut becomes intermittent? – and while normally I would use a tipped tool would I be better with HSS or a combination of carbide to begin and switch to HSS after the skin has been removed to avoid chipping the tool tip?

[Nick Clarke 3Participant @nickclarke3]

[Robin DuftonParticipant @robindufton85682]

Buy an insert for cast iron. There is a specific ISO code for it, K. https://www.sandvik.coromant.com/en-gb/knowledge/materials/pages/workpiece-materials.aspx.

You can look up a suitable insert on any of the manufacturers websites and get one for £5-6. Machining cast iron I've always used round inserts although I'd guess you don't have a tool for round inserts.

Edited By Robin Dufton on 24/04/2021 22:00:08

[Phil H1Participant @philh196021]

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

[ZanParticipant @zan]

Ugh. That’s one bad casting

[OldMetallerParticipant @oldmetaller]

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.

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