A closed-loop DC motor should work fine if your power supply is beefy enough, the encoder has enough resolution to work at low speeds, and the PID constants are stunned correctly.
A DC motor running open loop likely would slow or stall when a load is applied. It would be instructive to measure the DC current through the motor when it slows and stalls. This should be the motor's max-rated current, and the motor should be generating its full rated stall torque. On Mon, Jul 26, 2021 at 3:55 PM Earl Weaver <[email protected]> wrote: > Hi, > I have a lathe spindle with 8 in. chuck that is run with a 5HP Reliance > DC Motor and Reliance DC Drive. > I just cannot get much power out of it at low RPM. Was trying to turn > 8in OD steel, at approx. 200 -250 RPM with .005 in. cut. It didn't work, > it just stalled. > When I run it at low RPM the chuck rotation is movable, not firm. > I can take a hold of the chuck and hold it and move it back and forth as > it rotates. > It also is more noisy at low RPM. > > This lathe is a Linuxcnc retrofit with J Elson's Universal PWM > Controller and DAC Spindle control. > The DC drive has tachometer feedback from the motor. > I have tried numerous times to adjust, tune the drive, without success. > I also tried closed loop control from the spindle encoder within LCNC, > also no success. > > So here come the questions: > Should I keep trying to get this DC Drive working or would it be better > to switch to AC Variable Frequency Drive? > If I would switch to AC VFD would 5HP AC Motor be sufficient size for > existing 1:1 ratio double v belt to drive 8" spindle chuck? > What torque at low RPM can I expect for this 5HP DC motor? am I > expecting to much from it? > Would there be a better drive option for the existing DC motor? > Any recommendations? > > Thanks, > -- > Earl Weaver > Email: [email protected] <mailto:[email protected]> > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
