APT High speed, high hardness end mills - anyone used them?

[Voicecoil]

Perhaps I'm missing something but it looks to me more like a job for the lathe (to make the fundamentally cylindrical body), followed by the mill (to position and drill 4 holes), then bang some pins in the holes. How were you planning to use the end mills?

304 isn't actually very hard (typically HRB 70 ie it doesn't even make the bottom of the HRC scale) - and being stainless you can't through harden it either. Machineability is different to hardness. Some form of carbon steel would be a better, allowing you to machine it easily and then harden it with a torch and a bucket of water. Then you'll get something nearer HRC60.

If it's an emergency and you are short of carbon steel, how about using an old cold chisel, crowbar etc as a donor. Cut a bit off with an angle grinder, heat it up to a cherry red and let it cool. Then you should find it easy to machine. It's easy enough to harden up again using the bucket of water etc. You can get tools like this at Aldi etc for peanuts if you don't have any.

While you are figuring this out, you could be letting some penetrating oil slowly do its business....

Thanks for the input guys. Yes, I was looking to do the counterboring on the lathe, then start the 4 pin holes on the CNC, followed by drilling to full depth (cobalt drill, thankfully I have some from the previous project). The other task for the CNC is to cut a hex on the other end of the tool to put a spanner on. Sadly I don't have anything carbon steel of suitable diameter that could be sacrificed, about 18mm seems the biggest and it's far from straight. Normally it wouldn't be a problem, I'd go round to the local agri engineer and scrounge a bit - but of course things are not at all normal at the mo, and the nearest town is a bit away - not that I'd want to go there anyway. I do see one or two eBay metal traders still functioning though so if I can get by for a few more days of topping up the offending tyre that might be the way to go.

It would be interesting to know if anyone has experience of using these cutters anyway (they're 4 flute on a 1.8KW spindle Jazz
), they seem a bit of an oddity, but could be useful for other stuff as well. The high RPM is a bit unusual, and I know I'm going to have to keep on feeding steadily as discussed before; I might just do a test cut with a 0.5mm DOC (enough to undercut the hardened zone) and see how it goes.