Thread: Denford VMC1300 - Rescued
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17-01-2019 #21
Well only two years later and my mill has become my primary project and I have made some progress.
I have the RMHV controller hooked up to the EM806 drives connected to the original steppers. I have also connected the home switches. I have used the original power supply and relay board for this.
This gives me the following good things.
1) Movement on all three axis
2) Control of all three axis using either the buttons on the controller or a MPG pendant
3) Homing set up.
What isn't so good is
1) the z axis brake is errrr .... broken (I managed to loose the spring that applies the brake)
2) More of an issue is I let the smoke out of the spindle dc driver. The good news is they are still available off the shelf the bad news is they cost about 200 quid....
I have a replacement (https://www.transdrive.co.uk/shop/pr...q-non-isolated) and I'm in the process of wiring it up.
To start with I have copied the settings (potentiometers and dip switches) from the old board but I'm now beginning to doubt the wisdom of this as the old board died on me and at some point previous to me finding it on a scrap heap someone has written the word BAD on the heatsink.
I'll need to find some info on the motor as the old board is set for max voltage of 50V which seems a bit low (ISTR Triacs go up to 180V). I'm also trying to figure out how to use the 0-10v output from the RMHV controller to set the speed as I'm not sure if I need some form of isolation between the two.
Hopefully I'm not too far from being able to cut some chips although I'm starting to think that I might be better off using MACH3/4 or Linux CNC rather than the rather limited RMHV controller.
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I'll need to find some info on the motor as the old board is set for max voltage of 50V which seems a bit low (ISTR Triacs go up to 180V). I'm also trying to figure out how to use the 0-10v output from the RMHV controller to set the speed as I'm not sure if I need some form of isolation between the two...Clive
The more you know, The better you know, How little you know
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17-01-2019 #23
I think the RMHV is essentially the same as the DDCSV, and I don't think there is an option to use step/dir for spindle control. And I don't think the 0-10V is isolated. The only way you could get it to work with a non-isolated drive would be with a 0-10V to 0-10V isolator, but they aren't common or cheap (IIRC the last time I looked they were upwards of £150).
The easier option would of been to get an isolated Sprint drive, however experience has taught me the motors on these are far more likely to fail and cause the speed controller to fail, rather than the controller to fail.Avoiding the rubbish customer service from AluminiumWarehouse since July '13.
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17-01-2019 #24
Your right the RMHV and DDCSV are more or less the same.
I'll use a pot connected to the sprint board for speed control for now.
After a bit of digging on the internet and head scratching I *think* I've figured out why the speed control was set for 50v. I think that the 50v is the voltage from the tacho at max speed rather than the max output.
But worried about your comment regarding the motor failing taking out the speed controller, what tests can I do on the motor to establish if its good or not?
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I think the RMHV is essentially the same as the DDCSV, and I don't think there is an option to use step/dir for spindle control. And I don't think the 0-10V is isolated. The only way you could get it to work with a non-isolated drive would be with a 0-10V to 0-10V isolator..Clive
The more you know, The better you know, How little you know
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17-01-2019 #26
Does that board isolate the PWM in from the 0-10V output?
I'm not sure if the 0-10V output from the DDCSV/RMHV will be compatible with that board. It would depend on if that board is simply relying on referencing the PWM voltage (should be fine), or measuring the actual PWM.
Actually, I've just checked the spec of a DDCSV, and it states the spindle output can be configured as a PWM, instead of analogue. I can't find any mention of whether it's isolated though.
The problem with SCR type drives, is the far more common non-isolated versions have the control wiring at near mains voltage, so your 0-10V source has to be isolated. Denford did use isolated drives in some machines, so yours may have an isolated drive, or your BOB PWM may be isolated. The only guaranteed way to check without knowing the exact board you've got, is to power the controller up, and then measure the voltage between the speed control terminals and ground (or neutral/0V).Avoiding the rubbish customer service from AluminiumWarehouse since July '13.
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17-01-2019 #27
Have a read of the manual for setting the pots. Plus I think there may be posts over on the Denford forum somewhere where the Denford guys give a few pointers for setting the drive.
Generally carbon dust builds up, causing ground leakage, and/or shorting between windings. However the motors are not the easiest of things to dismantle to clean properly. I damaged the tacho trying to get mine apart, but then I was more interested to see what was in it, as it was already destined for the skip as I upgraded to a servo spindle.Avoiding the rubbish customer service from AluminiumWarehouse since July '13.
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18-01-2019 #29
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Good to know.
Although I assume you meant to have those two voltages the opposite way around? ;-)..Clive
The more you know, The better you know, How little you know
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