[Maxxheadroom]

Hello everybody I have a fadal VTC 8030 with a Fanuc 18i that I am having what I believe to be an oscillation problem between my X axis motor and a scale. When the motor is quickly moved, or quickly changes directions it begins a very loud chatter which is caused by the motor vibrating I believe it is having a feedback issue between the motor and the scale. I am wondering if anybody can tell me the steps to disable the scale in this controller? I am going crazy trying to troubleshoot this, also on a strange side note there is a very slight amount of play in the motor coupler (which I will fix once I get this issue fixed) just as a test I shimmed the slop out of the coupler. I went from being able to slowly move the X axis back and forth to not being able to move it at all before it began chattering. Any help would be greatly appreciated!

[drdos]

The slop is your problem. Because the feedback from the motor doesn't match that of the scale, the machine will hunt to find position. Turning off the scale will only mask this problem as it is no longer in the loop. To turn the scales off you must change the following parameters:

1815 bit 1 to a 0. xxxxxx0x (x = don’t change)

1820 = 2
2084 = 1
2085 =100
2024 = 12500

These will only allow you to move for testing only. You can not run the machine with these values. To run the machine you must get the parameter list from Fadal.

[Maxxheadroom]

So here's where it gets strange and frustrating, I am quite certain you are correct in that the slop is my problem however like I said when I shim it out it makes things considerably worse. Also I had a Fanuc tech out here for most of the day earlier this week his answer after spending quite a bit of time messing with all sorts of parameters was "I'm not sure it must be mechanical". Now in his changing things he said he turned the scale off with the same results, but I am not convinced he actually did. After spending nearly 8 hours here I would think he could come up with a better answer than it's mechanical. Now having said that I am not overly concerned about a bit of slop the parts this machine produces really do not need to be very accurate. If I could get this thing to run even with the slop that would be absolutely amazing.

[drdos]

You could try parameter 2017 bit 7 make it a 1. Beware , sometimes this makes it worse

[generaldisarray]

I have dealt with a very similar problem. Fanuc 15mb. Buzzy ramdomly jumpy X axis. Spent a bunch of time messing with the parameters and trying to work around the scale feedback. The ballscrew did not seem really bad, but it was noisy. We had it repaired by the people who originally made the screw. The jumpy buzzing problem went completely away.

Moral of the story, a minuscule problem in the axis feed system causes big problems with scales.

[Maxxheadroom]

Thank you everybody for the advice, the powers that be have decided to bring someone out and have the ballscrew replaced and setup. Hopefully with the bit of slop that we have this will be the resolution to the problem.