CMC Servo motor drive recommendation?

[jfong]

These motors are listed as 1000rpm at 10volts. They should run just fine with a 24volt power supply.

Couple things that I can think of.

Power supply is faulty and not putting out the current that it is suppose to. Unlikely but you never know.

The gecko isn't reading the encoder properly and is faulting out. I've used us digital ones before but never the differential versions. You may have to contact Gecko to see if they are in fact compatible. Us digital does sell a install kit that you use to make sure the encoder disk is at the right height for the optical reader. Misalignment may cause bad encoder output. This requires a oscilloscope to check optical encoder output. Anyone you know that has one???

One thing you can do to check to see if the motor runs Ok is to directly connect it to a power supply. If you don't have a good working PS, you can use a 12volt lantern or car battery, it should spin about 1000rpm @ 10volts.

[thedudeabidez88]

I just directly connected a motor to a bench top supply. At 10 volts, nothing, at 24 volts it was rotating maybe 50 RPM. Would this mean all the motors I have are bad? I find that very hard to believe.

[jfong]

I live in SE michigan. Don't give up....If you want to send me a motor/encoder, I can test it out for you. I have a spare drives laying around I can use to test.

[jfong]

I just directly connected a motor to a bench top supply. At 10 volts, nothing, at 24 volts it was rotating maybe 50 RPM. Would this mean all the motors I have are bad? I find that very hard to believe.

Possibly since they should spin a lot faster than that. Remove the brushes and look at them. See if they are OK and not worn down all the way.

Datasheet. http://www.contraves-drives.com/pdf/D303005_d.pdf

For the "B" winding version it should spin 10.1 volts per 1000rpm.


Also make sure you hook up to the right pair of motor connectors and not the tach output.

[thedudeabidez88]

I'll remove the brushes on the armatures and check them tomorrow. I have nothing hooked up to the tach output. Just the red and black armature leads from the motor to the driver. Before I removed the original wiring from the motor, I marked what the leads were on the motor for ID. So im positive that I'm hooking up the motor right. I did try another motor with the bench top supply and all it did was twitch in one direction at the same voltage that I tried the other motor that I I said was rotating at 50 RPM. So yeah that to me sounds like bad motors. Let alone as you and the specs say, that at 10 volts these should go 1000 rpm. But on the other hand, if all 4 motors are bad, that is pretty mind boggling to me. Especially if two of the motors were from a different system.

[mike_Kilroy]

Put ohmeter across armature: what you get?

SHUD BE 1-2 OHMS

put ammeter (20amp scale) in series with ur 24vdc supply onto armature with shaft locked in vice.
What do you read?

SHUD BE 20amps.

if either not true, motor is bad. Get different motors.

[mike_Kilroy]

This assumes u do have b winding.

Do not leave 20amp on more than about 1SECOND: this is I ur peak current rating.

[Al_The_Man]

tried the other motor that I I said was rotating at 50 RPM. So yeah that to me sounds like bad motors. Let alone as you and the specs say, that at 10 volts these should go 1000 rpm.

Two more test to test the motor, try the free wheel motion of the shaft by trying to spin it, it should be free to turn, now short the armature leads and give it a sharp spin, it should brake against the spin.
Next try revolving them in say a drill press where the chuck rpm is know, say around 1000rpm and measure the DC voltage output, this will be the voltage required to extrapolate for say a maximum of 2500rpm.
Al.

[thedudeabidez88]

I measured with an ohmmeter the Pos and Neg armatures and it came out to be 1.8 ohms. The brushes look okay to me. I decided to try something, the way I have been hooking up the motor is based entirely on the original wiring from the machine. I have two machines, and all have the same wiring. The red and black on the back of the motor I have assumed obviously that they are the Pos and Neg armature brushes and the two tabs closer to the motor shaft in this picture were the tach brushes. Well I applied 10 volts to what is supposed to be the tach and it was spinning pretty fast and had torque. I couldn't stop it with my fingers...Now im confused. I dont have a wiring diagram on these motors, and like I have said I wrote down what lead was what on the motor from the original wiring. Two old systems were wired the same way. So either the original machine was wired wrong, or that it was right and im still not supposed to apply voltage to it....But the shaft turned fast and had torque...I hooked it up to the driver with that hook up to the tach and it immediately started spinning at powerup...No control....

So when I hook up the red and black leads to the drive, the shaft holds position with very minor torque, does not rotate when hooked up to a bench supply at 10 volts. But when I hook up the supposed tach....The motor turns fast, lots of torque, but no control with the encoder hooked up...Ughh.

[jfong]

If the motor is spinning but no control from servo driver then swap the A and B encoder lines. They are backwards.

[Al_The_Man]

I measured with an ohmmeter the Pos and Neg armatures and it came out to be 1.8 ohms.

Normally on a CMC motor the GRN/BLU pair would be the motor and the RED/BLK the tach.
The Tach would have very little torque if voltage were applied, which you should normally not do.
Al.

[mike_Kilroy]

or if easier just swap a and b motor leads. u must have tach and armature backwards - go with the 'new' way now and just swap enc or two motor leads - not both.

[thedudeabidez88]

YESSSSSSS! Finally its now working. That was the problem. I was not aware of the CMC color wire coding, perhaps if I had a wiring diagram I would have figured it out sooner. I am now using the new way, It turns out the encoder problem was that I had connected a CAT5 Cable that I had that had one wire that had a broken connection, the wiring was right to the encoder, just the broken connection. Thank you guys so much for all the great help. Now I can hook up the other motor to the other drive. I have already tested and axis calibrated the Y axis ballscrew. Perhaps I'll make a video of the machine running when I finish.

[jfong]

That's great!! A short video would be nice. Always good to see another CNC working.

[helium]

YESSSSSSS! Finally its now working. That was the problem. I was not aware of the CMC color wire coding, perhaps if I had a wiring diagram I would have figured it out sooner. I am now using the new way, It turns out the encoder problem was that I had connected a CAT5 Cable that I had that had one wire that had a broken connection, the wiring was right to the encoder, just the broken connection. Thank you guys so much for all the great help. Now I can hook up the other motor to the other drive. I have already tested and axis calibrated the Y axis ballscrew. Perhaps I'll make a video of the machine running when I finish.

An old post I know, but I'm trying to get an Anorad table running as well with one of those Cleveland servos. Has your conversion proved reliable?