Servo Motors missing input signal & making clunking sound

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Mac&Mark
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Servo Motors missing input signal & making clunking sound

Post by Mac&Mark »

We have just got our Optimum milling machine setup with 750w Servos with Dyn4 Servo amplifiers.
We bench tested the acorn and all seemed to be good
We then connected the Servo Drives one by one and tested the communication between the servo drive and the servo motors. All drives and motors tested ok.
We completed the auto tuning for each servo drive and the motors were quiet and the motion of the servo was smooth in both directions.
We tested the motion sending pulse signals using the DMMDRV software with pleasing results where the motion of the servo was quiet and smooth as per the tuning.
We then connected the drives up to the Acorn Controller and jogged each axis. We then homed the machine which was OK. We then attempted to carry out the fine tuning of each axis following the fine tuning procedure as per the Centroid Fine Tuning Procedure . The first movement was smooth and came out to be approx. 0.07 mm off the required dimension. We then updated the mm/rev for the X axis. On returning the axis back to the starting position. The servo started to make a clunking sound with intermittent movement and on returning to the datum the readout value was incorrect by a significant amount. We then found that the dial indicator did not show movement when jogged in +1 mode but showed increment on the screen. On watching the coupling, the motor appeared to be getting the signal but didn’t move. We then proceeded to re-tune the servos thinking that it might have been the servo parameters that might have been not optimum but this did not seem to fix the problem. We then auto tuned the settings again and tested finding the problem was still there.
Tonight, we isolated each axis and tested them one by one. All axes seemed to be quiet and moving smoothly. We turned the machine off and turned all drives on and proceeded to home the machine. The machines motion seemed smooth and it seemed that the drives were moving as instructed. We thought we would try and run the fine-tuning procedure again. On setup of the gauge blocks the machine was then jogged to zero off at the end of the gauge blocks. The datum edge was zeroed and the dial indicator was then jogged towards the other end of the gauge block stack. On doing this the servos started making a clunking sound again and on checking the indicator the table didn’t move as the table was jogged.

Please find images and video of the machine, cabinet internals and screen shots of settings https://photos.app.goo.gl/75Qh8fWJMZAwQHif6

Please advise what steps We should take to eliminate these issues.

Thank you
Regards
Mark & Mac
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martyscncgarage
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Re: Servo Motors missing input signal & making clunking sound

Post by martyscncgarage »

Mark & Mac.
First thanks for all the information you provided.
What you have there defies logic. If the drive is receiving the step pulses, the drive should move that motor the define movement amount. If it can't it should eventually fault out.

Users are reporting better results by connecting the DYN4 drives to the DB25. You might give that a go.
There have been posts on this issue in the last day or two.

I would be curious to know how you make out if you choose this route.
Marty
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cnckeith
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Re: Servo Motors missing input signal & making clunking sound

Post by cnckeith »

does the motor make the noise when Uncoupled from the machine?

ps, those couplers you are using are terrible.. get some made for CNC couplers.
cnc couplers.jpg
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joneg
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Re: Servo Motors missing input signal & making clunking sound

Post by joneg »

there is nothing wrong with his zero max servo couplings, i have used them with excellent results with high end siemens motors and controls with no problems
cncsnw
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Re: Servo Motors missing input signal & making clunking sound

Post by cncsnw »

Definitely test with the motors uncoupled from the machine. Ideally, I would remove the couplers and then remount the motors, so everything is the same except there is no mechanical load. Do you still get the clunking sound?

I agree with joneg that, in principle, there is nothing wrong with those couplings. They are very similar to ones I have encountered on Mori Seiki machining centers. However, it is suspicious that the clunking sound seems to come every 90 degrees, each time a coupler screw comes around. Perhaps the couplers are misaligned or stressed in some direction?
martyscncgarage
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Re: Servo Motors missing input signal & making clunking sound

Post by martyscncgarage »

cncsnw wrote: Tue Apr 14, 2020 1:52 pm Definitely test with the motors uncoupled from the machine. Ideally, I would remove the couplers and then remount the motors, so everything is the same except there is no mechanical load. Do you still get the clunking sound?

I agree with joneg that, in principle, there is nothing wrong with those couplings. They are very similar to ones I have encountered on Mori Seiki machining centers. However, it is suspicious that the clunking sound seems to come every 90 degrees, each time a coupler screw comes around. Perhaps the couplers are misaligned or stressed in some direction?
I must have missed something. It appeared they were moving the axis incrementally, but I didn't see the DTI moving? Maybe I didn't see it correctly....
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
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Mac&Mark
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Re: Servo Motors missing input signal & making clunking sound

Post by Mac&Mark »

Thanks for the suggestions.
We checked the alignment of the servo motor to the ball screw shaft and adjusted to eliminate any chances of misalignment. We did a test with the coupling removed from the machine and the motors didn't make the clunking sound. We then reattached the coupling and jogged the table around. The clunking sounds came back. Just to see what the motors sound like when driven using the DMMDRV software and connected with the same coupling we did a test of 80000 pulses forward and back the sound did not appear. https://photos.app.goo.gl/P1VPHoqDBEFXucSs9
If the coupling was the cause of this problem wouldn't the clunking be heard when using either the DMMDRV or Centroid Software?
We will continue to investigate the couplers and will try connecting the DYN4 drives to the DB25. We will let you know the results.
Thanks
Raceman17
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Re: Servo Motors missing input signal & making clunking sound

Post by Raceman17 »

Your problem sounds like mine. I'm waiting on DMM to tell me what to do to fix the issue. I'm thinking it's the db25 connector as well.
slodat
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Re: Servo Motors missing input signal & making clunking sound

Post by slodat »

I highly recommend trying the Acorn DB25 step and direction outputs.
cnckeith
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Re: Servo Motors missing input signal & making clunking sound

Post by cnckeith »

those zero max couplers have to be installed just right..they are not very forgiving for diy users on the installation. we have seen problems many many times that was traced to these type of couplers so i am speaking from experience and do not recommend them for DIY installations.
When requesting support READ THIS POST first. http://centroidcncforum.com/viewtopic.php?f=60&t=1043

Please ALWAYS post a FRESH report. To make a report: https://www.youtube.com/watch?v=Ecvg0VJp1oQ.

(We pride ourselves on providing timely solid technical support but, without good information we may not be able to help and/or reply until such information is posted.)
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