if anyone has a suggestion for machining a cavity in 316L stainless I would appreciate it. I used a 5/8 Sandvik bullnose to get as deep as I can but the walls taper down and I have to get the rest of the material out with a 1/2 in. ballnose endmill. I have tried HItachi, Diejet and Dapra and all of them with poor results. I am beginning to wonder if a solid carbide ball would do any good.

For solid carbide I'd go with TiAlN or TiCN coating. The -SS series from Dataflute or the SGS ZEE CARB have always worked well for me. I would drill out as much as I could, but I assume that you will have already thought of that. 316 is reasonably tough so good luck.

:cheers:

I have found 316 a nightmare, it seems fine then you get it a touch hot and it work hardens and it will blunt any HSS coated or not in a moment.

I would go with the coated carbide suggested by cdlenterprises and keep it really cool :cheers: - the 316 and the beer :)