4th Axis Servo motor Oscilate when idle

[dexter910]

Hi guyz,

we are building 4h axis for CNC milling mashine. Everything was ok until we made a decision to switch to servo (from stepper). The reason was the idea to get high speed and to use 4th axis as lathe...

Hardware:

Servo motor is original Chineese servo

https://www.aliexpress.com/item/Serv...ceBeautifyAB=2

The problem is that the driver does not have USB connection so we can not adjust parameters using any software. Its done by UP, DOWN, ENTER, BACK on the panel....

You can see the problem in the following video:

https://drive.google.com/open?id=128...QZJiMI3cmJ7UjN


We need to have the motor withuot oscilation but we have no idea how to set all those PID parameters.


Here is also PDF with all parameters of the servo driver:

https://www.machsupport.com/forum/in...0;attach=44811




Any help is welcome!


Thanking you all in advice!

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[CoAMarcus]

Does the problem happen only when you push that block by hand? Is the motor stable normally until it is pushed out of position?

This looks like it is going to be a combination of two things: A misadjusted PID loop and too high of a gain setting on the PID loop. What is your encoder line count?

[awerby]

If you're using a normal rotary table with planetary gearing, there's no way it's going to go fast enough to operate as a lathe. You'll just destroy your rotary table by trying to do that. If you really want to make your milling machine into a combination mill/lathe, adapt a lathe head to the bed and power it with a regular motor - it doesn't have to be a servo - using a pulley cluster to get various speeds. If you want to be able to mill on the turned parts, work out a way to fix it firmly in position while you do that - or swap the rotary table back onto it, with its restored stepper motor.

[dexter910]

Does the problem happen only when you push that block by hand? Is the motor stable normally until it is pushed out of position?

This looks like it is going to be a combination of two things: A misadjusted PID loop and too high of a gain setting on the PID loop. What is your encoder line count?

This happens only when I try to rotate the shaft. When I stop it, it stays idle (does not start to move from itself).


I dont know where to find the information for encoder line count. It has some kind of electronics gear (3 parameters) to set units per...

[dexter910]

If you're using a normal rotary table with planetary gearing, there's no way it's going to go fast enough to operate as a lathe. You'll just destroy your rotary table by trying to do that. If you really want to make your milling machine into a combination mill/lathe, adapt a lathe head to the bed and power it with a regular motor - it doesn't have to be a servo - using a pulley cluster to get various speeds. If you want to be able to mill on the turned parts, work out a way to fix it firmly in position while you do that - or swap the rotary table back onto it, with its restored stepper motor.

Lets say that it should work as combo, so both of your ideas wont work...