http://www.mycncuk.com/forums/diy-pr...s-spindle.html

it might be worth having a butchers at this thread
the larger motors is 240kv so will run upto 2800rpm on 12v and has plenty of torque sub 1000rpm, works well on ally (iv not tried this on 24v but im sure it would handle it ok if you can stop the ESC getting too HOT)
the next one down in size is 820kv (upto aprx 10000rpm 12v) and will cut ally with 3mm tooling