Polishing Filler in Cast Iron?

Newly enthused by finishing my first model (Stuart 10H) I'm about to embark on a Stuart Beam kit bought second hand from another reader.

The flywheel casting has some pretty noticeable casting pits - big enough to warrant filling IMHO - returning to Stuart is obviously not an option.

Presumably one of the metal-containing epoxy fillers would be the thing to use but as a comparative newby I'm not sure what would be best to get the optimum colour and finish to match a well-polished rim - a dull patch might look as bad as the original pit.

Advice from you old hands would be welcome.

A Happy and Prosperous New Year to everyone.

JB Weld is a metal impregnated epoxy. It is a grey colour but not sure if it will give an exact color match.

A woodworking method for filling holes is to mix sawdust from the part your are making and glue as a filler. You could try cast iron dust instead. Try on a sample first.

Paul's CI dust and clear epoxy is going to be better than JBWeld which comes up a bit dark. You really need to heavily load the epoxy with the dust, the more the better.

You generally don't need to go for a polished finish unless you really like your bling, 180grit will give a bright enough finish. Use the abrasive on a firm backing pad so you don't get dips as it removes the softer epoxy at a faster rate than the iron

I have used ali, copper and brass powder in epoxy as in this pen. How cast iron will react with the epoxy I do not know so best to try mixing a small amount and just let it set before using it on the casting.

Stuart list the flywheel as a spare part for £14 +vat+postage so if you cannot get a satisfactory repair that you can live with you could buy a replacement if funds permit. It could always be painted but most people probably prefer a bare metal finish polished to your taste.

Mike

Thanks for the responses.

As a long-time wood turner I'm used to filling (made) grooves with an epoxy/metal powder mix using copper, brass and aluminium to simulate metal inlays and should have thought of this as probably the best solution. In my experience the metal powder needs to be as fine as possible else the polished finish can tend to look a little powdery and 'glittery' - and as Jason B says the epoxy needs to be as loaded as possible. I expect the cleaning up of the castings will give plenty of opportunity to produce fine powdered CI!

The beam flywheel is actually listed by Stuart at £38 + VAT + postage - money which could better be spent elsewhere, if I had it, I think.

A now deleted response pointed out that the flywheel on 'the real thing' would not have been polished anyway which, together with this post, has made me think rather more about the finishing of models in general - perhaps I'll bring this up in another thread.

Dalboy - Nice looking pen.

Oops, I didn’t read your post properly and checked the 10H flywheel. The beam item is rather more expensive so well worth trying for a repair solution. Sorry for the bum info on the flywheel, must read more carefully.

Mike

Mike: I recognized the price of a replacement 10H flywheel having had to buy one last year - the original having irremoveably welded itself to the stub mandrel I used for turning the back side. Ouch.