Stainless

[Jerry]

Stainless is used in all sorts of things, especially things related to science and industry due to its corrosion resistance and non-outgassing attributes.

Some of the common types you may run into

303 - This is considered free machining stainless. If you can use it in your application, do so.
304 - This is the stuff used in food grade equipments and vacuum systems. Dosnt machine too bad and welds easily.
316 - This and variants are used when you need extra corrosion resistance. Chemical valves and body jewelry are made from 316. It can be a pain to machine
17-4 - This is a pretty generic stainless. I have had no real issues machining it.

The main thing when working stainless is to remember that is work hardened very easily. Keep the tool cutting material, dont let it rub. If you do the metal will become hard. Another problem with it is it can be difficult to get it to break a chip when turning on a lathe. There are carbide inserts with chip breaker geometry specific for stainless.

Here is a video of my lathe taking a cut in 17-4, 1/8 deep cut (1/4 off the diameter), .0065 inch feed per rev, 800 RPM. See how it just makes razor wire!



Welding: Most stainless have their own specific rod but 309 will cover most materials when its not critical. When MIG welding dont waste your money with the tri-mix or other special mixed. 98-2 or 97-3 Ar/CO2 is all you need and a whole lot cheaper.