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  1. #25
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    Default Re: Scary VM10U problems

    Problem came back, the machine is down more than it's up. Now most recently the cutting is pushing the C axis around and it's losing the encoder position. That doesn't make any sense to me. The encoder shouldn't ever lose position- from what I understand it is a glass scale and it should always know where the table is even if the table moves in an undesirable manner (the servo and the encoder have different responsibilities- the servo to move the table, and the encoder to know at all times where the table is).

    The C is being pushed enough to trip the parameter and stop cutting, and re-zeroing isn't returning the table to the same position. I wish this was a problem someone could guaranteed fix for some amount of money but I feel like if I had Hurco service it, they might be servicing a good working machine of this type and that they might leave and the machine continue to operate like this. We have had it serviced recently by hurco- the new encoder install. We have rebuilt the o-rings, so it's absolutely air tight- when we were in there the brake metal parts seemed minty fresh. I don't get it. We have a Mazak with a Nikken 4th- it operates perfectly fine. We have a Mazak VCU 500A 5X and it works. We have 5 subspindle lathes with Fanuc controls and they operate 10 combined rotaries that never lose position and always work right. This Hurco rotary doesn't work right and I can't wrap my head around it.



  2. #26
    Member Jim Dawson's Avatar
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    Default Re: Scary VM10U problems

    Quote Originally Posted by Green0 View Post
    Problem came back, the machine is down more than it's up. Now most recently the cutting is pushing the C axis around and it's losing the encoder position. That doesn't make any sense to me. The encoder shouldn't ever lose position- from what I understand it is a glass scale and it should always know where the table is even if the table moves in an undesirable manner (the servo and the encoder have different responsibilities- the servo to move the table, and the encoder to know at all times where the table is).

    The C is being pushed enough to trip the parameter and stop cutting, and re-zeroing isn't returning the table to the same position.
    I would say that there is a mechanical disconnect between the encoder and the table, or the encoder and/or wiring is defective and there is noise on the line. I guess the problem could also be the encoder counter on the controller.

    I would expect the axis to trip out (thus shutting down the machine) on an excess position error, but it should not lose the table position unless the encoder signal is not properly getting to the controller or is mechanically slipping.

    Jim Dawson
    Sandy, Oregon, USA


  3. #27
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    Default Re: Scary VM10U problems

    Quote Originally Posted by Jim Dawson View Post
    I would say that there is a mechanical disconnect between the encoder and the table, or the encoder and/or wiring is defective and there is noise on the line. I guess the problem could also be the encoder counter on the controller.

    I would expect the axis to trip out (thus shutting down the machine) on an excess position error, but it should not lose the table position unless the encoder signal is not properly getting to the controller or is mechanically slipping.
    We tightened the jam nut on the encoder to the table and check tightened the bracket, so the belief is that the encoder is not mechanically slipping. The end mill is pushing the C position during a cut, or feedback is happening during the cut because we can see movement of the C axis registering during the cut before the machine stops cutting. At that point the table is now moved is the new part of that problem.

    I agree with your thoughts. What I guess is terrible about having this problem is that I don't get the feeling Hurco has the knowledge to send a tech who is able to 100% definitively diagnose and fix this machine inside that visit or even two visits. I wish I had a better feeling about their technical ability to resolve it so it doesn't re-occur. On our Doosan machines, I have about 100% confidence that ellison will resolve a problem. The biggest difficulty in saying 100% is that we just don't have problems with the Doosan machines- they are nearly unstoppable brick ****houses. On our Mazaks it seems mazak can troubleshoot and identify the problem but may have trouble getting a field tech out to work on it. On our Yama Seiki's, Yama seems very good at diagnosing and can get people on a plane if the customer wants them on the plane to fix it. On the hurco, we can get a tech out, but we've had different support here twice (once an encoder had failed, this last time it was believed the marker was too close to the proximity switch in degrees, we also replaced all the brake O-ring seals, and the problem is still here, and has even developed now into a second problem of losing position of C.

    This could be the wiring, the servo, servo wiring, or servo drive, the plc, the encoder, or the brake, or a combination of these. If it was an encoder, it would mean the Fagor IP64 (not waterproof, but humidity resistant) encoders might only last 2 months in the field.



  4. #28
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    Default Re: Scary VM10U problems

    I guess another possibility is that there is slippage between the drive and the table. In the drive system, if there is some kind of mechanical connection between where the encoder is connected and the table then the problem could be there.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Scary VM10U problems

    Has anyone checked the belt between the servo motor and the rotary table. pull that cover off the front of the C axis, the belt should be tight and take some finger pressure to move..if the the brake was bad and It leaked oil or coolant got into the cavity it could have made the belt weak,
    the brake should for the most part hold it in position but there are special circumstances that can over come the brake. I have seen people have A axis at 90 the a long part drilling with a large bit outside the radius of the table.it over torque the c axis. just strange now one can zero in on it.



  6. #30
    Member Mecanix's Avatar
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    Default Re: Scary VM10U problems

    You should have received a support contract upon reception of your machine tool. Therefore, and *in the real world*, we normally log mechanical failure and when this was reported to the supplier's support in-writing (down to the minute). This should be CC'ed to both supplier's sales mgt & support teams with scanned signatures. Needless to add that this log should include any financial losses due to the equipment failure(s). Taking the proper steps in getting your suppliers to fulfill they promise, and to prevent them from suffering from a breach of contract, can lead to some quite impressive response time customer service-wise (talking about hours, max!).

    Equally important; and if "out of service contract", your internal risk mgt team should have a budget for spares and/or emergency replacement parts from at least two different suppliers (with PO ready for this).

    Irrelevant to your current mechanical issue, I understand, although I hope this could help in the future.

    G'luck



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    Default Re: Scary VM10U problems

    Quote Originally Posted by Jim Dawson View Post
    I guess another possibility is that there is slippage between the drive and the table. In the drive system, if there is some kind of mechanical connection between where the encoder is connected and the table then the problem could be there.
    This is the major problem- the Hurco support phone puts a wait of several hours between the customer and getting some form of communication back. So the process is segmented into many 3-8 hour blocks of communication hoping to reach someone with some mechanical understanding of the machine such that they can take the symptoms and diagnose the source of a problem to resolve.

    I have no confidence we've reached anyone who has total understanding to the effect they can actually take the symptoms and diagnose a source to target for repair, so it seems more like we would have technicians out who would confirm the table moves under its own power with no cut, leave, and we would have continued issues and need for more 3-8 hour blocks of lost time communicating on a path to a solution. Not having any understanding of the length of time between us and a solution or the cost, it is really tough to make a financial assessment of what makes sense. It leaves you wishing the machine was 3 axis with a 4th rotary or something more simple that could be diagnosed and repaired effectively in the field.

    This machine is in a 4 machine cell, and the settup operator in the cell loses production on one or more of the other machines when he spends time trying to work the Hurco support for some sort of information or path to a resolution. It's unlike any other manufacturer support problem we've ever had, it seems more like hopeless. What you want to hear is, "for $6000 we can have that reliable for the next several years or something like that." not watching multiple attempts fail to resolve the problem for more than a few weeks.

    I just called a local supporting dealer here and after explaining what has happened asking if they had confidence and knowledge to work on table issues and they suggested they didn't know much about the rotary table issues and we should continue to work with Hurco for support. It is odd because the VM10U is the entry level 5 axis machine, so it would seem that it should be the most common 5 axis machine in the Hurco lineup, and the most known and understood.

    Last edited by Green0; 08-22-2019 at 12:04 PM.


  8. #32
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    Default Re: Scary VM10U problems

    I think this machine is going to be a never ending battle until you drag it out the door. Here is the solution https://us.dmgmori.com/products/mach...ing/dmu/dmu-50

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Scary VM10U problems

    Quote Originally Posted by Jim Dawson View Post
    I think this machine is going to be a never ending battle until you drag it out the door. Here is the solution https://us.dmgmori.com/products/mach...ing/dmu/dmu-50
    If Hurco support never improves I think you're totally correct. I don't even look at 3 axis Hurco's anymore, it's just too much risk to have even a decent machine that has low quality support.

    We have a Mazak VCU500A-5X here and the only issue with it is that the settup parameters aren't perfect for TCPC so we are probing parts on different rolls to make good cuts with it. It arrived with a warped trunion leg because it was shipped with a pad loaded on the truck, and there are a few thousandths the table is not flat on account of that far leg being pushed upward from centerline. The Hurco TCPC worked good until the table started to lose its encoder position. The DMU-50's are interesting I've seen a few almost new at affordable prices like $99K but usually with 8000RPM spindles and we're cutting aluminum so it seems like that would be pretty slow.

    The hurco can make impressively accurate work when the machine is letting itself cut through a program, but the table brakes are very weak so you have to really baby the heck out of it or it's going to trip over itself- refuse to go on, or worse lose table position completely.



  10. #34
    Member Jim Dawson's Avatar
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    Default Re: Scary VM10U problems

    If that Herco were in my shop, I would just make it work like I wanted. If that means re-engineering the system and replacing all of the controls then that would happen. I can't imagine bringing in tech support to service my equipment. I am the tech support, even for my new Haas.

    But, my shop is not a commercial high production environment, just a step above a home hobby shop. My production is limited and is for my own in-house products with a little product development and prototyping thrown in. Sometimes my machines sit idle for weeks at a time. If I were trying to make a living as a real production job shop then I would replace the machine with something that would make me money rather than cost money.

    Jim Dawson
    Sandy, Oregon, USA


  11. #35
    Member Mecanix's Avatar
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    Default Re: Scary VM10U problems

    You must have a technician in your shop who can trace (log) the encoder's signal? There are only 3 signal wires on a scale (??), get him/her to do some work a bit. Establishing whether the encoder, joints or plc is at fault takes roughly an hour or two. Ideally you'd also need to trace the time the brake takes to engage and disengage (in ms) and sync the motion. I'm suspecting rotation before the brake's full disengagement - that could be a reason your encoder gets fooled. You've tried placing a short period G4 before rotations and see if that helps?

    What sort of control/plc Hurco runs on this VM10? looks like a custom siemens vnck package



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    Default Re: Scary VM10U problems

    Quote Originally Posted by Mecanix View Post
    You must have a technician in your shop who can trace (log) the encoder's signal? There are only 3 signal wires on a scale (??), get him/her to do some work a bit. Establishing whether the encoder, joints or plc is at fault takes roughly an hour or two. Ideally you'd also need to trace the time the brake takes to engage and disengage (in ms) and sync the motion. I'm suspecting rotation before the brake's full disengagement - that could be a reason your encoder gets fooled. You've tried placing a short period G4 before rotations and see if that helps?

    What sort of control/plc Hurco runs on this VM10? looks like a custom siemens vnck package
    The control is Windows NT or something like that based. We don't have people here who can troubleshoot the trunion or electronics internal to the company and hurco techs have been out here. It almost seems like ideal for the machine would be a rebuild service where they just took it apart, inspected, and reassembled with torque wrenches and stuff to confirm everything was put together to whatever specifications they have, and replacement components used if needed. That might fix it. In Taiwanese machines, there are often assembly issues that cause problems to happen in my limited experience with Taiwanese machines. I prefer to buy Japanese or South Korean machines on account of their higher quality in my experience. I've had not the greatest luck with Taiwanese machines.

    I think Taiwan could do the world a service and just get out of CNC machines altogether.



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