On Thursday 11 April 2013 22:13:10 Jon Elson did opine: > Gene Heskett wrote: > > Somebody thinking "outside the box", and making perfect sense. The > > only fly in the soup is the 10,000 step encoder, and servicing it at > > 200 rpS to get that 12,000 rpms > > If you run a stepper motor at 12,000 RPM, it will burn up in minutes. > You can spin a typical stepper with the spindle motor, and above 1000 > RPM it will > get very hot with no current at all in the windings. That is all iron > loss. 12,000 RPM will require insane voltages be applied to the drive, > several hundred Volts. A typical stepper may generate 50 V at 1000 > RPM, so that would require a 600 V supply just to equal the back EMF at > 12K.
And I never considered the iron loses Jon, but you are dead on. > Oh, but then cogoman said : > > "the stepper motor could be designed with less steps per rev. " > > Yes, then why make it a stepper at all? How about an 8-pole > brushless servo motor? These work GREAT, used by Fanuc > since the late 1980's, and now available from many sources. > I make affordable servo amps for brushless motors, and > have one on my minimill. You do need to get rotor position > info from the motor, most small ones have Hall sensors that > you connect to the servo amp. I use 500 cycle/rev encoders > on mine, that is quite satisfactory. > > Jon That also makes great sense as long as its economical enough to do. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> Evil isn't all bad. A pen in the hand of this president is far more dangerous than a gun in the hands of 200 million law-abiding citizens. ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
