HAAS Counterweight Failure
Close
Login to Your Account
Page 1 of 2 12 LastLast
Results 1 to 20 of 27
  1. #1
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default HAAS Counterweight Failure

    Will post a more detailed update later, doing everything I can to get parts out the door on my backup machine right now...

    Saturday night I heard a bang and then repeated thuds while machining some softjaws. Somehow the counterweight in my '93 VF3 snapped one of the chains. It is now dangling from one chain, wedged sideways inside the column. I stopped the machine when I realized what was happening, but in a panic did not have the presence of mind to realize the chain was slack on the remaining side and the Z servo was taking all of the load instead of sharing with the counterweight.

    I rushed off to tractor supply to get similar sized chain, lifting gear, eyebolts, etc, and when I got back I had a Z servo overheat alarm.

    The mill had gone into Estop, dropped the head (luckily hung up before smashing my tool and vises), and apparently cooked the Z motor even though it alarmed out....so now on top of a mechanical issue I have a dead servo as well. Short to ground.


    I disabled all the axes so I could get it to come up and let me "run programs" without zero returning any axes. I blocked the head and attached the broken half of the second chain to a piece of steel spanning the column.

    I removed the toolholder from the spindle, manually opened the toolchanger door by removing the guide pin from the back, and retrieved my tools with M39 T# so I could use them in my other machine.



    It's been a hell of a weekend. I have been up all night trying to get parts finished and start working on fixes.


    Basically, I am thinking of doing the following:
    -Weld up a lifting frame that fits over the column
    -Attach eyebolt to weight
    -Hoist counterweight to remove weight from chains.
    -Place steel bar through support holes in column to support counterweight in a stable manner.
    -Replace both chains whenever the HAAS parts site comes back up or I can get in touch with my HFO
    -Remove Z servo, send it off to be repaired
    -Removed Y servo, swap it in to the Z position while Z is being fixed
    -Jog Z off table, test counterweight. If needed, this can be done before changing the chains- I'll have to see what access is like.
    -Hopefully have a working mill again?


    In any case, time to go machine shopping because I can't afford to have downtime like this anymore.

    I will update with progress, pictures, and more coherent descriptions when I have slept and as available.
    If anyone has recommendations for someone to repair a HAAS brushed servo or where I could find a replacement that won't cost a fortune, please let me know. Thanks.

  2. #2
    Join Date
    Sep 2006
    Location
    Long Island, New York
    Posts
    572
    Post Thanks / Like
    Likes (Given)
    180
    Likes (Received)
    74

    Default

    Quote Originally Posted by npolanosky View Post
    Will post a more detailed update later, doing everything I can to get parts out the door on my backup machine right now...

    Saturday night I heard a bang and then repeated thuds while machining some softjaws. Somehow the counterweight in my '93 VF3 snapped one of the chains. It is now dangling from one chain, wedged sideways inside the column. I stopped the machine when I realized what was happening, but in a panic did not have the presence of mind to realize the chain was slack on the remaining side and the Z servo was taking all of the load instead of sharing with the counterweight.

    I rushed off to tractor supply to get similar sized chain, lifting gear, eyebolts, etc, and when I got back I had a Z servo overheat alarm.

    The mill had gone into Estop, dropped the head (luckily hung up before smashing my tool and vises), and apparently cooked the Z motor even though it alarmed out....so now on top of a mechanical issue I have a dead servo as well. Short to ground.


    I disabled all the axes so I could get it to come up and let me "run programs" without zero returning any axes. I blocked the head and attached the broken half of the second chain to a piece of steel spanning the column.

    I removed the toolholder from the spindle, manually opened the toolchanger door by removing the guide pin from the back, and retrieved my tools with M39 T# so I could use them in my other machine.



    It's been a hell of a weekend. I have been up all night trying to get parts finished and start working on fixes.


    Basically, I am thinking of doing the following:
    -Weld up a lifting frame that fits over the column
    -Attach eyebolt to weight
    -Hoist counterweight to remove weight from chains.
    -Place steel bar through support holes in column to support counterweight in a stable manner.
    -Replace both chains whenever the HAAS parts site comes back up or I can get in touch with my HFO
    -Remove Z servo, send it off to be repaired
    -Removed Y servo, swap it in to the Z position while Z is being fixed
    -Jog Z off table, test counterweight. If needed, this can be done before changing the chains- I'll have to see what access is like.
    -Hopefully have a working mill again?


    In any case, time to go machine shopping because I can't afford to have downtime like this anymore.

    I will update with progress, pictures, and more coherent descriptions when I have slept and as available.
    If anyone has recommendations for someone to repair a HAAS brushed servo or where I could find a replacement that won't cost a fortune, please let me know. Thanks.
    This happened to me at my last job, I had a forklift though so I was able to put a strap around the counterweight and lift it up with that. There was no problem with the Z servo though.

  3. #3
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    Found somewhere who will rebuild my motor for about $1k. Going with that option, and meanwhile trying to sort out how to lift this thing. Due to machine positioning, a forklift isnt really practical.

  4. #4
    Join Date
    Jul 2006
    Location
    Hillsboro, New Hampshire
    Posts
    6,476
    Post Thanks / Like
    Likes (Given)
    1546
    Likes (Received)
    4514

    Default

    Wire rope come along? And does it make any sense to look into a nitrogen/hydraulic cylinder counterbalance rather than mass? That's what's on my 97/01 Haas mills. Around 1.5" (VF-2) and 2" bores (VF-5) with ~750psi.

  5. #5
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    Yeah, that's pretty much where I'm at. I have a chain hoist rated for 3t and a wire rope come along rated at 1T. Just going to grab some big steel tubing and build a pseudo-gantry-crane in place. Damn thing is so tall though, will need to buy more steel. I only usually buy 6 or 8ft lengths since they fit in my truck easily.
    I have no idea how I would retrofit a nitrogen cylinder, and I don't really feel like creating yet another project. Just want my mill running, ya know?

  6. #6
    Join Date
    Jan 2017
    Country
    UNITED STATES
    State/Province
    Oregon
    Posts
    2,198
    Post Thanks / Like
    Likes (Given)
    404
    Likes (Received)
    1608

    Default

    This story kind of freaks me out,I have a '93 VF2.

    Where did the chain fail? Was it up high where it goes over the sprockets? Was it lubricated? Is the counterweight provisioned for a lifting eye? Can you reach it?

    This sounds like kind of a nightmare scenario.

    I've hit mine with chain lube, but never serviced it beyond that...

  7. #7
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    I'll take some pictures for you in a bit. Yeah, it failed up high over the sprockets. One of the chain pins sheared. The counterweight is provisioned for a lifting eye, dead center. It should be within reach but I am nervous working around it right now in case the other one fails.
    I may need to pull back the cable track for best access. It was lubricated, but near 30yrs of fatigue must have done it in. It is about an inch below the access holes in the side of the Z column- I just need to lift it enough to shove a beam through there and take the weight. The bearings still seem fine, but I may look at replacing them while I am at it just to be safe.

  8. #8
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    Edit: Aaaand they all uploaded sideways, of course. Whoops. Sorry bout that.

    Attachment 248485
    Sad HAAS

    Attachment 248486
    You can see the crooked counterweight through the slots. If I can lift the bottom of it above one of these slots I can support it to make the repairs.

    Attachment 248487
    You can see the failed chain on one side. That'll be fun to access. Not sure how to do that yet.

    Attachment 248488
    A little bit of insurance, maybe. Broken chain half being held by the kant twist on a piece of steel in case it un-wedges itself before I have it supported.

  9. #9
    Join Date
    Jan 2017
    Country
    UNITED STATES
    State/Province
    Oregon
    Posts
    2,198
    Post Thanks / Like
    Likes (Given)
    404
    Likes (Received)
    1608

    Default

    Dang, I think I better give mine a thorough inspection.

    Add that to the list of things that can go wrong anytime on these old machines.

    At least it didn't cut loose completely and take out the Y-axis motor too.

  10. #10
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    Hey, it's not over til gravity wins. We've still got some precarious lifting to do. But I have parts to make first, so I'll do that once I ship these headache-inducing parts.

    Went shopping for a machine this afternoon. Found a candidate (2010 VF2) but turned it down for the moment- There's another machine, slightly older, but loaded with options and in pristine shape that I think fits the bill for us.

  11. #11
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    The lifting hole is 1/2-13 thread and 2" deep. Buying 1x mcmaster 3014T491 for the counterweight and 1x 3018T29 for my lifting rig.
    Using a 2000lb rated cable come-along. I have a 3t chain hoist but it's hooks are way too large for the eyebolts.

    Chains were $180 from HAAS, and Haas 0728-06-029, 93-32-1300, VF1 & VF2 Axis Servo Motor Repair | Motor Repair & Rewinds | Eurton Electric is repairing my motor for $950 or less if it doesn't need a full rewind. Getting new bearings and brushes with that too.

    Looking for bearings right now- They are 6206D2S. I assume that is 62x30x16mm, Deep Groove, Sealed both sides.
    Edit: Got bearings. Called Boca Bearing who is local-ish and they found me what I needed. MR6206-2RS by Boca Bearings :: Ceramic Bearing Specialists

  12. Likes jancollc liked this post
  13. #12
    Join Date
    Jun 2013
    Location
    Northern Il
    Posts
    1,202
    Post Thanks / Like
    Likes (Given)
    657
    Likes (Received)
    1169

    Default

    Quote Originally Posted by npolanosky View Post
    Found somewhere who will rebuild my motor for about $1k. Going with that option, and meanwhile trying to sort out how to lift this thing. Due to machine positioning, a forklift isnt really practical.
    Why do you think your motor is bad? I would suspect an issue directly related to possible shorted wiring.

    The servo motors and amplifiers are pretty robust and just because you get an alarm and especially the short to ground, does not mean the servo motor is bad.

    Unless you actually verified the servo motor was shorted to ground by checking the resistance across the winding legs and to ground at the motor with the wiring from the servo amplifier unplugged, you likely have another issue which might be a lot cheaper to remedy.

  14. #13
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    Quote Originally Posted by Ziggy2 View Post
    Unless you actually verified the servo motor was shorted to ground by checking the resistance across the winding legs and to ground at the motor with the wiring from the servo amplifier unplugged
    Yep, that's what I did. It definitely cooked itself. Low resistance continuity to ground.
    I get about 2 ohms across the windings, and 88 ohms to ground. That should be measured in megaohms, correct?
    The motor folks say if it doesn't need a full rewind it'll cost less, which works for me. I just know that if I send it to the pros it's on them if they screw it up, whereas if I crack it open and ruin it I need to buy another from HAAS for $3500. I'm too busy putting out other fires anyway, so I'm happy to pay the man and just have it fixed.

  15. #14
    Join Date
    Jan 2017
    Country
    UNITED STATES
    State/Province
    Oregon
    Posts
    2,198
    Post Thanks / Like
    Likes (Given)
    404
    Likes (Received)
    1608

    Default

    Quote Originally Posted by npolanosky View Post
    The lifting hole is 1/2-13 thread and 2" deep. Buying 1x mcmaster 3014T491 for the counterweight and 1x 3018T29 for my lifting rig.
    Using a 2000lb rated cable come-along. I have a 3t chain hoist but it's hooks are way too large for the eyebolts.
    I was thinking- if you don't like sticking your arm down in there, you could thread a piece of all-thread into the counterweight. Then use the all thread as a kind of "puller". Thread it into the weight, and span the top of the casting with a steel bar with a clearance hole for 1/2". Put a nut on it, and go after it with a wrench to take the weight off the chain and bring the weight up to a position where it's easier replace the chains.

  16. #15
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    That is way simpler than the rig I just designed, FEA simulated, and am halfway through welding. Hah. Oh well, if it's worth doing it's worth over doing. And if anyone else has a counterweight failure...i guess just lemme know since I have a tool for it now? Hah.

    I also needed a change of scenery, and overengineering a project is always a nice distraction from the usual stress which still feeling semiproductive.

  17. Likes ferretlegger liked this post
  18. #16
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    Finally got the motor back. Thank goodness I have another mill. Putting the poor HAAS back together tonight, hoping it goes smoothly. I assume I will need to reset the toolchange position and maybe a few other things.

  19. #17
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    Counterweight rollers have new bearings
    New counterweight chain installed
    Counterweight hanging under it's own weight.
    Z motor reinstalled
    Z motor works
    Machine homes
    Jogged to table, checked distance with haimer- .1134" off from previous distance. Easy enough to tweak.
    Rapid back to home, encoder fault. Jog quickly, encoder fault.
    Alarm 141, Z Servo Z Fault. Dammit.
    I wonder if it got damaged in shipping or during the motor repair. Sigh.....
    A shame, because everything is running smoother than ever otherwise.

  20. #18
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    Alright, so it seems perfect at or below 75IPM/25% rapids. It has issues beyond that intermittently. Is there any way to clean/repair the encoder, or do they just "go bad" and that's it?

    Edit: Turned the machine on this morning. 184 cable fault. Of course. Time to pull it all apart and figure out what the motor repair people screwed up. They fixed the motor and broke the encoder or cable.
    Last edited by npolanosky; 03-02-2019 at 03:37 PM.

  21. #19
    Join Date
    Apr 2016
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    358
    Post Thanks / Like
    Likes (Given)
    281
    Likes (Received)
    110

    Default

    Pulled everything apart. Found a cracked solder joint on the A/ line of the encoder coming off the PCB. Also found a smashed connector between the encoder and the cable that runs through the motor to the junction box on the back of the motor. When I put the cap on the back of the motor it dislodges the VCC line on the encoder cable (among others) and causes the alarms.

    The 184 cable fault indicates there isn't a valid differential signal coming from the encoder. I guess that would be the case if the encoder wasn't powered up

    When I had everything open I took apart the encoder too, inspected it under a microscope, and cleaned off some dust particles from both the disc and the sensor with isopropyl alcohol and kimwipes. There was definitely some debris that could have caused the Z channel errors at high speed. It's amazing how small the 2000 slots are for the incremental count.

    For future reference by me or others, the encoder has the following specs:

    5v
    Differential (pins A, /A, B, /B, Z, /Z, 5V, GND)
    Z/index channel
    8mm through bore
    1.78"ish mounting pattern
    2000 count per rev

    The one in this particular servo was a "Changchun Rongda Optics Co LTD. NVC37T8-G0.15M1L-2000BM no. 20180503041" which is a mouthful, but I am not confident this one is original. It could have very well been replaced in the past based on the witness marks on the end of the motor not matching the silhouette of the current encoder's mounting bracket.

    In any case, I am ordering a spare encoder of the same specs from AutomationDirect to have on hand, applying some hot glue to the wiggly wire, and putting the old mill back to work!

  22. Likes Milland, Chris59, BGL liked this post
  23. #20
    Join Date
    Jul 2006
    Location
    Hillsboro, New Hampshire
    Posts
    6,476
    Post Thanks / Like
    Likes (Given)
    1546
    Likes (Received)
    4514

    Default

    I like your persistence! Good luck getting it working right, and thanks for the updates.

  24. Likes Chris59 liked this post

Tags for this Thread

Bookmarks

Posting Permissions

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