Quote Originally Posted by m_c View Post
Having a quick look at the catalogue, 11.170 are a high helix version of what I use, which will help with chip clearance.

I'm not sure about what settings are in Huanyang VFDs, but the one you want to alter is for current. IIRC there is some setting whereby you can limit the current once a certain frequency is reached, but it's been along time since I read a manual. There will reach a frequency, where current will be limited by the maximum power available, which a good VFD will handle without any problem, but I'm not sure how a Huanyang will.

11.170 has a cutting speed of 40-65m/s (2961 to 4811rpm for 4.3mm diameter), with a suggested DOC of about 0.13 to 0.2mm per revolution. At 12500rpm, even at 0.1mm DOC, you're looking at 1250mm/m feed rate.
Running the figures through my spreadsheet, that equates to a cutting torque of 0.5 to 0.8Nm.

The postage cost from phantom is high if you're only ordering a couple drills, but I normally order over £50 at a time, so it's not so big an issue.
Thanks. Ive checked some of the settings of the VFD online, Ill need to check tonight to see if its set right.

So clearly 75mm/min is nowhere near the right amount. Ive noted other machines that have high speed spindles just simply plunge and drill in what looks to be a millisecond. These are not always with spindle/tool through coolant. Clearly at 75mm/min I was just rubbing and dulling the tip.

I may order some of the German endmills and donate them for breaking / testing. Must be a way to get this right. In hindsight, I should have tested this on some scrap metal before doing it on the actual part. That said, small piece of alu, not the end of the world, the part will still work, just looks a bit crappy where the broken drill moved around in the hole.