Gene Heskett wrote: > On Saturday 03 January 2009, Dean Hedin wrote: > >> Take this one for example: >> >> http://www.hobby-lobby.com/brushless-gazaur.htm >> >> The R/C motors are rated with "Kv". Which means rpms per volt with no load. >> The above motor is rated at 4100kv and can go up to 12volts. >> So that would be 49200 rpm. >> >> > That link says up to 14.8 volts, which would be nearly 61k rpms. > > But surely a motor of that size cannot be rated for CCS service. 450 watts of > input (30+ amps at 14.8 volts) would fry it in 2 or 3 minutes even if it was > pumping its own cooling air. Or at least I'd think so. And this is the sort > of info I'd need. Bearings aren't mentioned either, and even torrington > needles have limits of around 150k rpms for their teeny cartridges needles. > Well, the ultimate motors for this are Westwind air bearing spindles or Rockwell/Precise high speed spindles. The Westwinds are really designed for drilling, but can be used for light routing, too. You have to be real careful to keep the radial loads down to avoid crashing the air film in the bearing. These are about 2" diameter and 6" long. The motor rotor is about .7" diameter all the way, just a plain cylinder with a "hat" on the end for a thrust bearing. It will produce at least half a HP, and can go up to 80,000 RPM. It runs great on a VFD, although my VFD only goes to 400 Hz, so you get 24,000 RPM max.
I also have a Rockwell/Precise spindle that will go to 45,000 RPM, and is rated at 3/4 Hp. It uses a 2-phase motor, so i don't have a proper system to run it yet. I did fire it up on a Gecko stepper drive, however, and it did run. I'm not sure it would develop rated power on that. The oldest Precise spindles have universal motors, and can be run on a Variac. Jon ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
