new laser trouble with servo motor

Hi, i just bought a new laser 4x8 feet. this laser made with servo motor and rack/pigon. it use a rudia 6332m dsp controleur nad i use it with lightnurn. my toruble is whne i try to make round at fast speed 50mm/sec the round come ovale in diagonal. when the round is ccw the oval is from right to left and when the round is cutted cw the diagonal is from left to right. i tried to change offset setting and acceleration setting but always get similar result. when i try to cut a 15 or 20mm/s it very better. i think teh trouble sould be teh pid in the servo drive itself. is it posible to try to ajust pid on servo drive to have more acceleration?

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Originally Posted by arachid78

Hi, i just bought a new laser 4x8 feet. this laser made with servo motor and rack/pigon. it use a rudia 6332m dsp controleur nad i use it with lightnurn. my toruble is whne i try to make round at fast speed 50mm/sec the round come ovale in diagonal. when the round is ccw the oval is from right to left and when the round is cutted cw the diagonal is from left to right. i tried to change offset setting and acceleration setting but always get similar result. when i try to cut a 15 or 20mm/s it very better. i think teh trouble sould be teh pid in the servo drive itself. is it posible to try to ajust pid on servo drive to have more acceleration?

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Maybe the Acceleration/deceleration time constant is too small which caused the overshoot is too big.
Try to Increase acceleration/deceleration time constant.

Acceleration wouldn’t cause oval circles. Check that the belts are tight. Check all pulleys to shafts to motor are tight. Check calibration on X and Y axis. Does it draw a square? Are all settings on X-Y stepper motor drives the same? Are all X-Y settings on the controller the same? That assumes pulley diameters are the same.


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If You bought a big new laser, it´s assumed for a business.
Get someone experienced to come and take a look.

For 500$ you can get excellent advice, and the problem may or may not be solved.
No way You will get great results online, trying with unknown machine and quirky controller and random servos.

A facetime/zoom consult from someone will almost certainly help a lot, and for 200$ or so in 2 hours or less.

Hi,
the best toolpath following requires the highest acceleration possible, so it not improbable that your problem may be helped by increasing the acceleration.

The issue you have is that you did not program the servo drives to start with, in fact can you even tell us the brand and model number? Have you tuned servos before? If not, then don't fiddle with them,
its more likely that you'll make it worse as it is you'll make it better.

I personally would not touch them UNLESS I had the servo manufacturers manual in front of me, and had the manufacturers set up and tuning software, and the manual that accompanies it.
If there is no manufacturers set up and tuning software then you have to program the drive by pushing buttons like programming a microwave.....don't do it! It is very time consuming and
error prone.

Without the manuals and setup software you would be advised to follow hanermo's suggestion, get an expert to take a look. Whats the bet an expert, perhaps especially an expert,
would shy away from fiddling with the servos without the manuals and the software.

If you've just bought this machine why does the supplier not help you out?

Craig