Re: 24,000, 30,000 or 40,000 RPM - Jianken Spindle
IF, you run flood coolant and use very small cutters you can feed MUCH faster at higher rpms. I am currently running 24,000 rpm spindles on 3 machines. For engraving and some types of small detail work the feed rates seem almost glacially slow. I use 1/16 inch ball mills everyday, and its not uncommon for me to use .026 inch ball mills for slotting grooves in aluminum for inserts. BUT if you go with faster spindles you run into issues with larger tools that may work better at lower RPMs.
I have never gotten a clear answer as to whether or not the low torque at lower rpm is mitigated by using a 4 pole motor as opposed to the more common 2 pole spindle motors.
Bob La Londe
http://www.YumaBassMan.com