End mills / Drill bits for aluminium

[ivars211]

Thank you both for such descriptive answers. I read here that you can have your inverter "tuned" to get lower rpm, but I guess that's wrong then.
Anyway, JAZZCNC, where did you buy your end mills, and do you have any suggestion for good price-performance wise end mills for aluminium?
I guess I will need 6,8,10 mm 2 flute end mills for pocketing and something like 8mm 3-4 flute for inside-hole finish.

Thank you again!

[Jonathan]

People too often confuse torque and power. They are related by a simple formula, but represent completely different things. Power is torque times speed (if you use the correct units).

With the correct control (which is not necessarily easy) you can get rated torque at *any* speed from the spindle. That doesn't help you much though, as at 1000 rpm you're at 1/24th of the rated speed, so at rated torque you have 1/24th of the rated power - so less than 100W.

The problem with drilling is you generally need *more* torque, so just getting the rated torque (about 1Nm) isn't so helpful. You can use tricks like the one you linked to and exceed the ratings of the motor to get more torque (e.g. just apply a higher voltage at low speed), but I certainly wouldn't recommend it when this is something you need to do regularly. That's how I managed to drill several hundered 8.5mm holes with a carbide drill using my spindle:

Homemade CNC Router aluminium bed drilling with coolant - YouTube

I also occasionally drill aluminium with the spindle at around 4000rpm with a 4.2mm HSS drill, but I wouldn't recommend doing it regularly.

[JAZZCNC]

Anyway, JAZZCNC, where did you buy your end mills, and do you have any suggestion for good price-performance wise end mills for aluminium?
I guess I will need 6,8,10 mm 2 flute end mills for pocketing and something like 8mm 3-4 flute for inside-hole finish.

I buy most of my tooling from cutwell tools but I'll buy from Ebay when I see quality cutters come along at right price. Buying cheap cutters is false economy in long run because if they snap the potential for wrecking the job is high and at very best time is wasted. On some jobs this can wreck expensive material and you can bet your last penny the bastard will snap 10mins from end of 6hr job.!!
Only time I'll use cheap cutters is if they are so cheap I can afford to throw away after each job or I have lots of little jobs so can keep an eye how it's working.!

Like Jonathan says and you have seen you can tweak the VFD to give more Torque but your messing with fire and can easily fry something and will certainly shorten it's life so is it really worth the trouble.? If you need torque which you really do for drilling then really you need to look at a differant setup for the spindle. Something like Collet spindle in a housing connected to a normal motor 2 pole 3 phase motor via belt drive and gearing 3:1ratio to 1000rpm would give you the torque required.
If done correctly you could design a back plate system so they could be swapped over for when you require milling.? This is really the only way you'll get reliable drilling without getting silly on price for the correct spindle.