584,858 active members*
4,570 visitors online*
Register for free
Login
Page 1 of 2 12
Results 1 to 20 of 21
  1. #1
    Join Date
    Jun 2005
    Posts
    104

    Torq-Cut 22 Z-Axis Over Current Alarm

    The previous owner of this Torq-Cut 22 that I recently purchased told me that they were having problems with rapid movements in the Z axis. When the machine rapids in Z, I get a "Z Axis Drive Over Current Fault". What they advised as the work-around was to change all G00 moves to G01 movements at 40 IPM. Did it and it works. I would still like to fix the root cause. Any advise?

  2. #2
    Join Date
    Dec 2008
    Posts
    4
    If there is any noise in the axis it could be the bearings. They might be putting excessive load on the axis.

  3. #3
    Join Date
    Jun 2005
    Posts
    104
    Thanks for the reply. No, spindle is one of the quietest I have ever heard. Machine is in pristine condition. Came out of Georgia Tech lab. I changed my Max and Jog rate to 100 ipm in parameters and machine does fine. Seems like anything over 150-200 ipm and I get the Over Current Fault. Has something to do with the servo drive I think. I am trying to figure out what Z-axis servo drives it is using.

  4. #4
    Join Date
    Sep 2011
    Posts
    75
    Look at the z axis motor and see if it is the parvex motor
    The tag can be read on mine from the back side looking down in the column
    These machines dont have a counterweight on the z axis and the original motor was not up to the task of driving the z axis up under high loads as in a rapid.
    They were than retofitted with the Parvex motor and higher ouput drive to solve the issue
    I believe there is a parameter that could be changed to reduce the maxium feedrate during a z axis rapid call

  5. #5
    Join Date
    Jun 2005
    Posts
    104
    It is a Parvex motor. I changed the parameters for Max and Jog rate to 100 ipm. That seemed to fix the issue for now. I was talking to another machinist recently and he said he reduces the default max feed rates on the Z-axis on all his machines to reduce the wear and tear on the servos. Would still like to know what the root problem is. Thanks for your response.

  6. #6
    Join Date
    Jun 2005
    Posts
    104
    Guess I spoke too soon. After changing the jog rate to 100 ipm, I no longer get an Axis Drive Over Current Alarm, now I get a "Following Error Limit Exceeded" alarm. It all revolves around the Z-axis. Looked at the Maintenance Page and the Pos-Err for Z was .050. I get that because the axis was jumping as it moved in the + direction. What stands out to me is the column next to it. Under DAC-CMD all the other axis read -1024, but Z reads -967. When in the jog mode, I can jog X and Y and that number fluctuates a little but returns to -1024 once I stop. The Z axis on the other hand, when I move down in the - direction, it looks ok, but when I move up in the + direction, it drops to about -870. And this is when I get either of the alarms is when it is moving up in the + direction. Any help is greatly appreciated.

  7. #7
    Join Date
    Nov 2004
    Posts
    3028
    Remember that there is no counter weight. That is why Bridgeport retrofitted these machines with the much larger Parvex motor. But this is still a DC motor with brushes. It is possible that they are worn down. i have yet to replace a Parvex motor or brushes. It is more likely that the axis drive board has issues.

    George
    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  8. #8
    Join Date
    Jun 2005
    Posts
    104
    Thanks for your reply. I am working with Gary Geltz (not sure if you know him) and he said the same thing, that he has never replaced one of these Parvex motors. This has taken a strange turn though. At some point while in the possession of Georgia Tech, McDaniel Machinery added Advanced Motion Controls "Brush Type PWM Servo Amplifiers" on each of the axes. Even stranger is they are connected in series with the original axis drives. Original axis drives are still connected to BMDC board. My understanding from a gentleman at GT was it was a bridgeport upgrade. According to Gary definitely not. Thought the installation looked kind of sloppy anyway. So, Gary is checking on that. Why, we don't know yet.

    I just ran the machine for two hours roughing an aluminum part down with no problems. Program went to perform a tool change and Bam, Z Axis Drive Over Current Fault. Cleared faults, re-homed the carousel, did a program restart, ran next tool and started noticing jerky movements in Z rapid moves. Wasn't long til she faulted out with the over current alarm again. So, I opened the electrical cabinet and this Brush Type PWM Servo Amplifier on the Z-axis is warmer than the others. But, I did notice that the cooling fan on the left (facing the inside door) is dead. I'll replace it Monday. One on right is still running. Anyway, then I climbed on top of the machine, removed the shroud and felt the Z-Axis servo motor. Very warm, not hot, just very warm. I am going to let her cool off for a while and try to restart the program again.

    I haven't had the machine long. Since about end of July. I bought it through a machine reseller that acquired it from Georgia Tech. What kind of stinks is they (Georgia Tech) told this guy about the Z-axis problem when he bought it from them. He never relayed that information to me because he says it never gave him a fault while it was in his possession. I guess I'm stuck with it so I have to get it fixed. Hard on a small owner/operator though.

  9. #9
    Join Date
    Nov 2004
    Posts
    3028
    Say hello to Gary for me. We are both part of the Jurassic service department. I have known him for many years. I still work for McDaniel Machinery (21 years now). And the inside of your machine does not sound "stock." I have never been to Georgia Tech but maybe Scott or Kyle who work with me may have been. None of us would parallel or serially connect axis drive boards. It is beyond their capability to do such a thing. I would be most interested to see such a arraignment. It is more probable that someone who did not belong fooling around with this machine, made the modifications. Did Gary have hands and eyes on the machine? ask him to call me. Maybe it is being described incorrectly.

    George
    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  10. #10
    Join Date
    Jun 2005
    Posts
    104
    George, I will be talking to him next week so I will mention that you said hey. Gary definitely sounds like he knows his stuff.

    I don't want to get anyone in trouble at McDaniel Machinery. I was only told by GT contact that he thinks the techs name was Adam from McDaniel Machinery that installed these components. He had no maintenance records for the machine so he could be mistaken. He said Gary knew Adam so Gary may be trying to contact him to find out for certain. Apparently Gary worked on this machine years ago. He made the comment that it was a well taken care of machine and GT never ran it hard at all.

    Gary has not touched this machine first hand but I did send him some pics. I have attached those pics showing the components. I originally sent these photos to the company I bought the machine from to show them that upon initial inspection of the machine after its arrival, these components were laying loose in the cabinet. They were surprised and apologized for overlooking it. There was one wire that was not even connected (holding it in pic). I connected it to the terminal on the relay next to the drive after comparing it to the other relays.

    I am swapping the Y and Z Amplifier to see if it changes anything. All of these "Brush Type PWM Servo Amplifiers" are identical so I don't see where it would hurt anything. If the problem doesn't go away, I figure I can deduce that it's not the amplifier. Consequently, if problem moves to "Y" axis then I know it's the component. Contacted Advanced Motion Controls yesterday and that is what they suggested. Have any idea what these are for exactly? Gary seemed stumped.
    Attached Thumbnails Attached Thumbnails IMG_0185.jpg   IMG_0187.jpg   IMG_0186.jpg  

  11. #11
    Join Date
    Jun 2005
    Posts
    104
    Think I can rule out the amplifiers that were added as being defective. They may still be contributing in some way. Let the machine cool for a few hours and re-started my program to run the other half and again, about two hours in and over current alarm strikes again.

    Can I check the brushes without removing the motor? I still need to measure the resistance on the motor armature. Need to find my meter first.

  12. #12
    Join Date
    Nov 2004
    Posts
    3028
    These drives are being sold by EMI as replacements for the original V2XT and EZTRAK drives. Never seen one used in a TC-22 as a replacement nor as augmentation. And what is the purpose of the relay?
    This is why I do not answer questions involving machines that are retrofits or modified. Too many variables. Stock machines keep me busy enough.
    I will check with my parts manager to see if he recalls such drives being sold to Georgia Tech and to what end. I will also check with EMI.

    George
    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  13. #13
    Join Date
    Jun 2005
    Posts
    104
    Please excuse my ignorance here but I am trying to wrap my brain around this Axis Over Current Fault.

    The Troubleshooting section of the manual describes this Z-axis Drive Over Current Fault this way: This message only applies to machines that have digital PWM servo drives. It is displayed while attempting to enable the axis drives. It appears when a Z axis PWM amplifier fault has occurred.

    OK, the servo motor has one set of cables running to the axis drive. Another set run from the encoder on that motor to somewhere else (not concerned about this for now). The axis drives send a specified amount of DC voltage to the servo motor and that determines the motor speed. It sends this voltage in either the + or - direction of flow that determines the CW or CCW direction of the spindle. My question then is, is the Z-axis drive over current fault a result of an over current in the servo motor or the axis drive itself? If it is an over current in the motor, it would stand to reason in my head that there is excessive resistance either cause by an excessive resistive mechanical load on the motor or excessive electrical resistance possibly in the windings of the armature. Am I close?

    And what does PWM stand for?

  14. #14
    Join Date
    Nov 2004
    Posts
    3028
    Had a chance to talk to Kyle today. He worked on this machine a couple of times. They were machining some compressed paper products and it caught fire. He had to replace all the oil lines beneath the table.
    He also informs me that the engineering department at Georgia Tech installed these additional drives with potentiometers to induce interference/harmonics into the drive system for experimental reasons. Good luck!

    George
    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  15. #15
    Join Date
    Jun 2005
    Posts
    104
    Hey George,

    Thanks for the information. I contacted GT again this morning and their response was: "The oil line repair and control changes were done by a certified technician and was done in the proper manner".

    I also had an industrial controls technician look at the drives modification this morning and he has determined that the new drives are setup on A/B switches on the side of the cabinet and are not active until selected by the A/B switch. Apparently they were using an external controller to control the machine. For what reason we aren't sure. These universities do some strange things. We plan on removing that mess at some point in the future. At this point it doesn't look like it is causing the problem.

    The tech checked the voltage on the machine and set the tap on the transformer to run on 245 volts. He was getting some high voltage readings on some of the electrical connections. He also said the cooling fan not working needed to be fixed. There was no fan blowing on the Z-axis drive. I moved the working fan over to blow on the Z-axis drive.

    Thanks for your input. Very much appreciated.

  16. #16
    Join Date
    Jun 2005
    Posts
    104

    Update

    Here is what I have done to address some of the issues I have been having with this machine.

    1. Removed all of the aftermarket drives and associated wiring that Georgia Tech installed. Reconnected axis motor leads directly to the OEM drives like they should.

    2. Found that the Z-axis brake was wired into the emergency stop loop. Put that back where it is supposed to be.

    3. Replaced the dead cabinet fan.

    4. Got a "Guards not in place message" while machine was running. Everything stops. The wires for the door switch were spliced where it comes out of the cabinet. Someone just twisted the wires together and wrapped with black electrical tape. Fixed that.

    5. Took the Z-axis motor to a qualified motor repair shop. They replaced the bearings. Said the bearings looked like crap. Commutator looked good, brushes looked great, and resistance through armater was .6 ohm. So motor is in good shape now.

    Machine runs great. Smooth and quite. Very accurate. Only one problem I have to address now. After about 3-4 hours of running, I get a "Following Error Limit Exceeded" message. Not sure what is causing that. I am thinking that the encoder cable needs to be replaced. Any Help?

  17. #17
    Join Date
    Nov 2004
    Posts
    3028
    Following error limit exceeded in which axis?

    George
    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  18. #18
    Join Date
    Jun 2005
    Posts
    104
    Sorry about that. It is in the Z-axis. I also noticed that this machine has a very high acceleration and deceleration rate in that axis as well. In fact, when it moves in the negative direction in a rapid move, it actually has a bounce at the end of its travel. Seems like there should be a parameter to curve that acceleration and deceleration rate. Parameter #10 (Accel/Decel Profile Selection) looks like it may have something to do with this. Parameter #128 (Z Axis Velocity Balance Flag) looks like it may have an influence on it as well. I changed this one to 15 myself because in the notes it says that "slideing head machines like Torq-cut should be set to 15". It was set to 0. The only other one I changed was #8 (Z-Axis Traverse Rate). I metered it down to 250 ipm because it was accelerating and decelerating so abruptly. I was thinking about re-installing the DX-32 software since the Georgia Tech Engineering Department experimented with an auxilary drive system on this machine. Who knows what all they may have altered while they were performing these experiments. Or at least reload the BMDCPRMS file to its original settings. I have attached the current txt version of the BMDCPRMS file. Unfortunately, GT could not find the software disk so I do not have a copy to perform a re-install. Currently it has version BOSS BPC-MC V4.79.22/6.89/57 installed. Know where I might get a copy of this or newer version?
    Attached Files Attached Files

  19. #19
    Join Date
    Nov 2009
    Posts
    30

    same problem

    I had the same problem last year
    and i made the same thing by changing the parameter
    of the z axis rapid movement

    and it works well now

  20. #20
    Join Date
    Jun 2005
    Posts
    104
    Just reading in the Maintenance Manual in Chapter 4 Section 2 under "The DC Motor Power Supply" it states that "Transformer T2 is tapped at 92 VAC and 100 VAC. These two taps permit a choice of 128 or 140 VDC applied to the axis motor drive cards. The voltage may have to be selected to accommodate the weight of the Z axis when accelerating in the plus direction. The 92 volt taps are terminals 10 and 13. The 100 volt taps are terminals 17 and 18. To change voltages, change wire 1 from terminal 13 to terminal 18 and wire 3 from terminal 10 to terminal 17". I wonder if this would help Z to keep position better so I don't get the "Following Error Limit Exceeded" fault. Anyone ever tried this change?

Page 1 of 2 12

Similar Threads

  1. Replies: 2
    Last Post: 11-24-2018, 09:15 PM
  2. X axis won't home? Bridgeport Torq-Cut 22 DX-32
    By hrhoward in forum Bridgeport / Hardinge Mills
    Replies: 20
    Last Post: 11-24-2013, 12:32 AM
  3. Torq cut 22. axis power supply failure,low voltage
    By Dirtman in forum Bridgeport / Hardinge Mills
    Replies: 0
    Last Post: 06-04-2010, 02:00 AM
  4. VF-1 alarm 162 Y axis over current
    By regen in forum Haas Mills
    Replies: 7
    Last Post: 10-23-2008, 01:38 AM
  5. Install of a Troyke 4th axis on Bridgeport Torq-Cut 22
    By RedGTZ in forum Bridgeport / Hardinge Mills
    Replies: 10
    Last Post: 10-15-2007, 03:10 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •