Alfred Smart wrote: > I have 1980 vintage wells index knee mill, > I have retro to emc2 from bandit using gecko's microstep 10x > using original power supply 45vdc and 2 original motors and one that is > newer but came with the machine. > 2 sigma instruments and one rapidsyn dana, all are nema 42 > The sigma's have no spec's and I can't uncover the spec's, and the > rapidsyn rate the amps at 7.5. > The gecko's are running wide open 7 amps, unipoler motors wired half > winding. > the sigma motor's seem tired and don't have much detent at all and > rapidsyn has plenty. If you mean when not powered, that is a feature of the motor design, some have a lot more detent than others. If you mean while the Gecko is on and powering the motor, then there may be a problem. Some of the old Bridgeport BOSS motors were set for about 11.5 A. Run at 7 A, they would be low on torque. (Also note the Gecko drives drop to 1/3 current when idle, so that would be about 2.3 A.) Some older drives could damage a stepper motor when a transistor burned out. If you can get an accurate resistance reading of the stepper coils, you might get a better idea of what currents they were set up for. The lower the resistance, generally, the higher the current the motor was designed for. Also, you can try to estimate the breakout force with the gecko being given a couple steps a second to keep it on full current. Just grab the pulley and try to stall it. You may want to wrap a big rag around the pulley to save your hands. It should take one HELL of an effort to stall or overcome the holding torque of a NEMA 42 motor.
Others have said the 45 V supply is on the low side for maximum speeds, and they are right. But, from the sound of things, this is NOT your problem now. If you can pull these motors out of lock with the above technique, then either the motors need more current, which the Gecko drive cannot supply, or the magnets are totalled. If you assume they may be totalled, then you can try running 5 or 7 A through them in the full winding configuration. If the torque is massively improved, you can at least run the machine like that while looking for other motors and/or a power supply upgrade. > When I run a program like the spiral.nrg the sigma motor will stall in > the change of direction part of the interpolation. > It doesn't seem to stall when jogging at slow speed or rapid motion. So, only on the reversal? Speed should be pretty close to zero right at the reversal, and low speed is where the stepper motor has the best torque. > max_volosity .65 > max_acceleration 3.0 > could these motor's need more current or are they used up > There is some talk about repair, anyone with any experience with this ave. > Wells quoted me $495. for used motors, I think I'll look elsewhere. Stepper motors are stepper motors. I sure wouldn't pay $495 for a used motor! Jon ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
