Hi Alan, > From: Alan Condit [mailto:condit.a...@gmail.com] > I built a new controller for my 9x20 lathe using a 5i25/7i76 combo. I thought > I had everything working but I still can�t get the spindle > working correctly. > I have a 1.5hp PMDC treadmill motor that I am controlling with a > Cycletrol-150 DC controller. The am using the analog out from the > 7i76 to replace the potentiometer to control the spindle speed. I have a 100 > slot encoder with index (homemade) on the spindle.
This is what I found for a Cycletrol DC motor controller. http://www.grahammotorandcontrols.com/item_dc_motor_controller/176B6002/58 There is no guarantee that a PWM output will emulate a potentiometer. That's the first place to look First put the pot back and measure the voltage between the wiper and ground as you control the speed from 0 to full RPM open loop. And depending on how it's powered be careful that the pot inputs aren't indirectly connected to ground. It's always possible the speed control won't work unless there is also 5K Ohm between pin 9 and 11. It's also possible the pot changes the resistance (as a rheostat) in a feedback circuit so input PWM may or may not work. Also PWM is exactly that pulse width. Unless you have a filter capacitor across that with a bleeder resistor to ground (Pin 11) the internal circuit many not integrate the PWM enough for it to work. For example I bought a small Chinese PWM to 0-10V module that has the rule that the PWM frequency can't be higher than 1kHz. Try it with 10kHz and it won't create a lower voltage. So PWM frequency is a parameter that must be correct. I also, way back, bought a step/dir to 0-10V controller that produced 10V at 25kHz step rate. The problem was my ELS was limited to 20kHz so I never could get 10V out of it. I don't believe your 100 PPR encoder is the issue. I'm running my spindle with 60 PPR and can do power tapping on the mill. It may still be possible to find these UHU or HP_UHU kits somewhere. I ended up using them because the GECKO servo drives I bought were only good to 80V and my servo motors like more than 90V. The HP_UHU kit was good to over 200VDC. https://www.cnczone.com/forums/servo-motors-drives/342836-uhu-servo-controller-build.html Similarly there are still some STMBL kits out there. These can actually take the smart serial input from the MESA boards or step/dir. I'm not sure that 0-10V was very implemented. https://www.pcbway.com/project/shareproject/stmbl_servo_motor_drive.html John > > The spindle starts under LCNC control but I am not getting an �at speed > indication� at above about 100rpm. The motor sounds like is > is running at a steady speed but the Spindle Speed indicator fluctuates > wildly. I am suspicious of the spindle encoder. Before I was > just running it as a 100 count counter with index and it worked fine. I can�t > figure out in PNCConf how to set up a spindle counter > with index for the 7i76. > > Questions: > Is it likely that my encoder is the problem? > I don�t know how to adjust the detectors to be out of cycle by 90�? Any > helpful hints? > Should I just go back to the 100 slot counter? > Should I replace my whole homemade encoder with a real commercial spindle > encoder? > > Sent from my iPad > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
