Quote Originally Posted by Robin Hewitt View Post
Well, maybe if the machine had another ton or so of cast iron to keep the toolpath sweet :heehee:

I suppose I could try it but suspect on a quarter ton machine I'd get horrible graunching sounds from a fat cutter and bits of shattered tool whizzing past my ears from the smaller sizes.

Have you actually tried cutting metal? :naughty:

(Slight exageration there, whenever the tool breaks it never seems to do anything more than drop off the shank, never whizzes anywhere) :whistling:
Err yes... I don't know what you are cutting (stainless steel perhaps?), but 6082T6 on my small mill cuts fine with an 8mm cutter at a feed rate of around 5mm/sec (which is about as fast as I can turn the handles manually - 2 revs/sec) and I would expect a powered table to move faster than that.

Some rough numbers... 8mm cutter, 60m/min cutting speed for alloy = 2300rpm on spindle (I whack it up as fast as the belts let me which is 2580 I think)

The chip load for alloy is approx dia/150 for roughing, d/200 for finishing. Assuming roughing chip load is 8/150 = .05mm so the feed rate @2300rpm for a 4flute cutter is .05mm * 4 * 2300 = 460mm/min = 7.7mm/sec

The material removal rate is depth * width * feed rate = 1 * 4 * 460/1000 = 1.84cc/min

Power(kW) = specific cutting force * removal rate/1000 = 17 (for alloy) * 1.84 = 31W (~1/20HP) and the torque needed is P * 60/(2pi * revs) = 31 * 60/(6.28 * 2300) = 0.13Nm

Doing the same with a 50mm facecutter its 400rpm spindle speed, 533mm/min (8.9mm/sec) feed rate and slightly less power. I know this is too fast for me to do manually which is why my surface finish isnt as good as I'd like with the 50mm/4tip facecutter compared to the 25mm/2tip one.. I havent yet tried the obvious and taken two tips off the bigger cutter...

I've only broken drills and two 3mm endmills... and nothing whizzes anywhere.. just snaps off flush with the end of the collet!