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MinnesotaHSM
04-05-2011, 05:56 PM
My brother-in-law would like some light machining done on a zinc model railroading casting. Any tricks to it? Any toxicity concerns?

Thanks.

- T

Dr Stan
04-05-2011, 07:25 PM
I would not grind or sand it as the power is pretty nasty (toxic). Depending on the composition of the alloy it could be from easy to absolutely a PITA to machine. If it is 100% zinc its gummy and will like to build up on your cutting tools. I know as I machined sacrificial zinc anodes when I was in the Navy to reduce salt water corrosion in some tanks. If it has a fair amount of aluminum in the mix it will machine much like aluminum.

Hope this helps.

macona
04-05-2011, 07:40 PM
Its probably not pure zinc but Zamac.

Evan
04-05-2011, 08:57 PM
Yep. probably Zamac. It machines nicely but it gets hot and it can dig in suddenly if the setup isn't really secure. When that happens it usually destroys the part.

Elninio
04-06-2011, 12:10 PM
Is it possible to machine zinc coated pieces without cashing peeling/fractures in the zinc coating? I know this doesn't work on chrome plated pieces. I don't have any such project, just wondering...

gary350
04-06-2011, 02:23 PM
Zinc machines a lot like brass you need a razor shape end mill. I use to machine a lot of prototype parts at work. We bought zinc in bars and melted them down then I hand poured the liquid zinc into small hand made molds that cast the zinc into blocks about 1/4" wider, 1/4" longer and about 1/2" thicker than the finished part. A dull cutter will produce a lot of heat. Zinc must be abrasive because a brand new end mill will work fine for several days then it starts getting hot. It was always best for me to use water cooling for a day then swap to another razor sharp end mill. The end mill that I removed would still cut steel fine.

macona
04-06-2011, 02:34 PM
Very sharp edge tool will be needed and probably a negative rake and/or clearance needed to help stop it from digging in. Try with something you dont care about first.