The Home Machinist!

Hoping one of you might be able to shed some light on a problem a friend of mine and I have been working on, I have cross posted it here from CNCZONE:

I have been working with Brian L. on his Milltronics Partner IV knee mill with Centurion V control. He is getting following error trips in ONE direction only on all 3 axis. I believe its the -direction on all 3. We are scratching our heads trying to figure out what is causing it. We pulled the timing belt of the X axis and tested the machine. (decoupled the ballscrew) following error seemed to be fine both directions. We manually turned the ballscrew and there was an ever so slight difference in resistance moving it back and forth. We don't think its enough to cause an issue.

We could see a weak servo amp or encoder if it was on one axis but all 3?
He has to run at 60 IPM or so, not to trip the machine. This machine is far more capable than that. Any ideas?? He has posted pictures in this forum. It has Fenner drives, I think they were 1270's (going from memory)

Any help to get this resolved and the machine running as it is supposed would be greatly appreciated. If money needs to be invested, we want to know that it is in the right places.

We HAVE followed the manual to set up and make sure the Servo Amps are adjusted properly. The computer has ACROLOC cards, though we aren't 100% certain which ones. Maybe one of you familiar with them might recognize them from Brian's photos.

Here is a link to the photos:
http://www.cnczone.com/forums/milltronics/141980-acroloop_card_tuning_info.html

Thanks in advance for the help!
Marty

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"Jack of all Trades, Master of None"

MOST machines have programmable following error limits, many with numbers for either direction....
this is because of weights and gravity -> axes often work with / against gravity and require different settings depending on direction of travel. (Think a VERY HEAVY Z AXIS)...comes down easily, but given the same current, may hardly move UP.

I don't know the cards you mention specifically so can be of no further help with specific parameters.

You didn't say - does this machine read encoders or scales?

Milltronics Partner IV, Centurion V control
Following error is supposed to be equal in both directions. .050 @ 100IPM
Runs fine one direction all axis. Going in the - direction all axis, it faults, following error accumulates rapidly.

Thanks Bill
Marty

_________________
"Jack of all Trades, Master of None"

Following error in servo drives can be summed up in two ways: mechanical, electrical.
If nothing is binding or loose mechanically, then go to electrical. Besides, mechanical problem would be only one axis.
Since it is effecting all 3 axis, check the power supply voltage feeding the motors in the direction that doesn't trip. Use this as a base point. Now check the voltage in the direction that is tripping and see what you get.

It sounds like you may have a motor power supply problem or a bad connection involving the PS somewhere.

Of course this is assuming that the following error is set the same in both directions in the motion controller/computer.

jim B

Jim, thanks for the response.
The power supply could not be anymore simple, no transformer, simply rectified AC.
The Milltronics Centurion V control says .050 @ 100ipm in both directions.
We did note with the servo belt off on X it appeared to run OK. We turned the pulley manually and it felt about the same, maybe a tiny bit more resistance in the other direction but surely not enough that should cause a problem.

Marty

_________________
"Jack of all Trades, Master of None"

try opening up the allowed following error until the fault goes away.

see what setting is NEEDED to run the machine...

try REVERSING the polarity of the motor to get it to run backwards and see if the problem follows the table or the voltage. You will probably need to rewire the encoder also.

adimttedly, it is a hail Mary, but....

On most of the systems that I have done, if one axis is messed up, then you should get a fault indicating that axis. However, this may not hold true with this system. I am not familiar with the Milltronics, but the theory is the same on all systems, servo or stepper. Identifying the circuits/part may be the problem.

Yes, as Bill said, open up the following error. At some point you may see which axis is the actual problem.

Also, even if the power supply appears to be "simple" the motion controller will still have a more detailed circuit.

I have PM'd you, with my phone number. It might be easier to discuss this in real time.

Jim Bronson

Jim they are all axis in the negative direction only. Brian, my buddy with the machine may call you.

We disconnected the belt on the X axis to the ballscrew and the following error appeared to be the same in both directions.

We did open up the following error, but eventually it climed and tripped the machine.

_________________
"Jack of all Trades, Master of None"

sounds like it is missing counts in one direction...maybe noise?

Can I assume the "following error" and "axis lag error" are the same?

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Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!

Hi Glenn,
Yes, I believe they are the same.

_________________
"Jack of all Trades, Master of None"

Thanks Marty,

I was just a bit curious.

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Glenn

Operating machines is perfectly safe......until you forget how dangerous it really is!