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

[Voicecoil]

After a couple of delays due to other stuff I finally had the opportunity to have a go at it today, and I have to say I'm impressed with the APT cutters. Sequence of machining was:

1) Turn down outer of bar to size ont' lathe, spot drill either end for centering.
2) Peck drill pilot holes for the 4 pin holes on the CNC, 4mm cutter.
3) Transfer to drill press and drill pin holes to full depth.
4) Drill a 10mm centre hole for the recess (lathe) - this made the subsequent milling much less arduous.
5) Enlarge centre hole & machine counterbore on the CNC - I didn't do this with lathe as my boring tool was a bit shagged.
6) Flip it over and machine the hex at other end.

I had to quickly turn a couple of pointy things that fitted into the collets to achieve the centering, but they'll be useful in the future no doubt. Seems to have turned out OK, accuracy is fine (apart from a small centering error on the centre hole) and the finish is pretty good -not that it matters really, it's only a tool - but nice to know for future work.


Things that I've learned about the cutters are:

1) You need a good lot of coolant when using them on steel!!!. Thankfully the pump on my mister has quite a range and fairly gobs it out when you turn it up - just need to sort out some sort of drain/recirculation to avoid puddles on the floor now
2) The stated RPMs on the APT site are OK for edging/shallow surfacing, but for anything deep & confined you need to take them down a fair bit: I ended up with 14K on the 4mm when drilling and it sounded fairly happy.
3) Although it seems to be possible to press on with a reasonable feed rate in X and Y, the Z plunge rate has to be far less.

But all in all these cutters are a useful thing - although you might have to take things gently, being able to machine steel on a DIY machine (made of aluminium!) is obviously useful. I'll get a few more next time I'm ordering from APT and maybe do some tests to see how hard they can be pushed.
PS thanks to Mike (Mekanik) for the bit of steel :-) )