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[Lathe] Fanuc OT to DC_CNC conversion
- Thread starter JimDawson
- Start date
- Joined
- Feb 8, 2014
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- 11,176
Thank you Karl.
So far the servos work as expected. Pretty easy to tune. I had a bit of confusion about wiring up the enable circuit, but that was quickly sorted out by an email to DMM tech support. They are very responsive and helpful. I would like more technical detail in their documentation, especially on the analog input functions. They tell you how to set it up, but I would like to understand a bit more of how it works internally and and how some of the setting affect the operation and interact with the external controller.
One odd thing is that the KP and KD had to be set higher on these than any servo I have connected to a Galil. 120 and 240 respectively. No problem, just a bit odd. I'm going to have another look at the DMM setup software, I may not have something set correctly. Both the X and Z are holding +/- 5 encoder pulses (about 5 microns). The 1.8 KW servos have about twice the torque of the original servos, so I expect good accuracy without sacrificing any speed. It's always easier to turn down the torque than it is to squeeze more out of an under powered servo.
So far the servos work as expected. Pretty easy to tune. I had a bit of confusion about wiring up the enable circuit, but that was quickly sorted out by an email to DMM tech support. They are very responsive and helpful. I would like more technical detail in their documentation, especially on the analog input functions. They tell you how to set it up, but I would like to understand a bit more of how it works internally and and how some of the setting affect the operation and interact with the external controller.
One odd thing is that the KP and KD had to be set higher on these than any servo I have connected to a Galil. 120 and 240 respectively. No problem, just a bit odd. I'm going to have another look at the DMM setup software, I may not have something set correctly. Both the X and Z are holding +/- 5 encoder pulses (about 5 microns). The 1.8 KW servos have about twice the torque of the original servos, so I expect good accuracy without sacrificing any speed. It's always easier to turn down the torque than it is to squeeze more out of an under powered servo.
- Joined
- Oct 14, 2014
- Messages
- 2,116
Did you tune with Galil Tools or Galil WSDK? How much KI?
IIRC, issue SH from galil to set enable, MO to turn it off. Don't remember the hard wiring off the top of my head. I do remember all AMC servo drives have an enable signal pin. Remind me more from here.
IIRC, issue SH from galil to set enable, MO to turn it off. Don't remember the hard wiring off the top of my head. I do remember all AMC servo drives have an enable signal pin. Remind me more from here.
- Joined
- Feb 8, 2014
- Messages
- 11,176
I tune manually using Galil Tools. Keep bumping up the speed and accel/decel, adjusting the PID manually as I watch the position error. Been doing it that way for years and I'm too old to change my ways now 
My KI is set to 0, I have found that setting to >0 many times causes overshoot. I'll be playing around with the tuning a bit more later.
Yes, SH and MO set the Enable output high or low depending on which chip you are using for the output (7407 or 7406). There was no problem with the Galil end, my opto relay was turning on and off just fine, but who would have thought that you would connect the drive onboard +14Vout to +14Vin (pin 17 to pin 4) to use the onboard power supply.
That one is not documented (or at least I didn't catch it) but tech support was helpful.
My KI is set to 0, I have found that setting to >0 many times causes overshoot. I'll be playing around with the tuning a bit more later.Yes, SH and MO set the Enable output high or low depending on which chip you are using for the output (7407 or 7406). There was no problem with the Galil end, my opto relay was turning on and off just fine, but who would have thought that you would connect the drive onboard +14Vout to +14Vin (pin 17 to pin 4) to use the onboard power supply.
That one is not documented (or at least I didn't catch it) but tech support was helpful.
- Joined
- Jun 12, 2014
- Messages
- 5,074
Jim,
You do impressive work and your wiring is beautiful. Fun watching this come along, takes a lot of guts and know how to tear a CNC machine down to basics and then make it better than the original machine. Thanks for posting.
Mark
You do impressive work and your wiring is beautiful. Fun watching this come along, takes a lot of guts and know how to tear a CNC machine down to basics and then make it better than the original machine. Thanks for posting.
Mark
- Joined
- Feb 8, 2014
- Messages
- 11,176
It's not quite that simple. Once you connect pins 4 and 17 together, you can then disconnect pin 15 (Enable) from pin 1 (GND) to enable the drive.
Now you can see my confusion. Thank you for the kind words Mark.
Last edited:
- Joined
- Feb 8, 2014
- Messages
- 11,176
Another update:
I have all the axes under control, finally. Calibrated the X & Z axes yesterday, and got the homing routine working correctly. Then I started on the tool turret code, got that finished up this morning. Then later today I managed to get the spindle under full computer control, I don't have the spindle indexing code done yet, but we don't need that or the live tooling immediately. The live tooling drive servo works, but I can't turn it on from the CNC program yet, still need to write that code. Still need to clean up a few loose ends in the code and interface, but the wiring is complete. Taking a break from working on the screen graphics right now. These 16 hour days are wearing me out, getting too old for this stuff.
I think tomorrow I'll be able to run a few air cuts and make sure everything is going to behave. Then I'll finish putting the rest of the sheet metal on, and clean up the wiring, get it all tied down properly. I hope we'll be making real chips by Monday, need to get some parts out the door. And I still need to get taxes done by 23:59 on Tuesday
Stay tuned......... Video coming soon
I have all the axes under control, finally. Calibrated the X & Z axes yesterday, and got the homing routine working correctly. Then I started on the tool turret code, got that finished up this morning. Then later today I managed to get the spindle under full computer control, I don't have the spindle indexing code done yet, but we don't need that or the live tooling immediately. The live tooling drive servo works, but I can't turn it on from the CNC program yet, still need to write that code. Still need to clean up a few loose ends in the code and interface, but the wiring is complete. Taking a break from working on the screen graphics right now. These 16 hour days are wearing me out, getting too old for this stuff.
I think tomorrow I'll be able to run a few air cuts and make sure everything is going to behave. Then I'll finish putting the rest of the sheet metal on, and clean up the wiring, get it all tied down properly. I hope we'll be making real chips by Monday, need to get some parts out the door. And I still need to get taxes done by 23:59 on Tuesday
Stay tuned......... Video coming soon
