how to synchronize two servomotors

Jasper 3 wrote: my servomotors get there cmd's in step dir signals. I set my servodrive up, so he runs in position mode. But not sure if you mean that?
The P value 1 is also ok but the servo overshoots a lot. For the p values I used the halscope. But I didnt connect the gantry cause of the whistle.

I have never set up a system with step/dir servos in position mode and with a PID in LinuxCNC HAL, though I am aware that it is the preferred method.

However, I _think_ that with such a system the P-gain should always be 1000. (and I _think_ that the other gains should all be zero)
Can you try this and see what happens?

hey,
I tried it but i makes fast oscillating movements.
when I run my motors in openloop modus than it works great. But than I have no possibility to synchronize my servomotors. After a while than by driver turns off and said overcurrent (I think because both motors work against eachother).

Jasper 3 wrote: when I run my motors in openloop modus than it works great. But than I have no possibility to synchronize my servomotors.

I don't think that is the case at all. Many people are using open loop stepper motors on gantry systems. Even though your motors are servos, in position mode they should work identically.

If the motors are fighting each other then it sounds like some sort of homing/squaring problem.

If the drives are running in position mode, Then they WILL have internal loops that must also be tuned before you can do anything with tuning them in Linuxcnc. Was that done?
Usually that has to be done using the drive manufacturer's own drive configuration software. (Often using a Windows PC.) Doing that could be a complicated trick on a duel motor gantry.

hey,
thanks that makes sense. I know they have an internal loop, otherwise they wouldn't work in openloop mode. On my X and Z axis erverything works well. (There the internal loop is ok - i think) And I can run my servomotors in a closed loop in Linux. Tuning the X and Z axis was no problem.

So now I tried to run my Y-Axis with one motor connected via timingbelt to both ballscrews. In closed loop it doesn't work (always oscillates and tuning was not really possible) But in openloop it works great and it's not possible that the motor turns off. It get's a bit warm because one motor alone is a bit weak for that load.

When I have both motors on the Y-Axis with no timingbelt:
My Y-axis runs in Openloop modus for about 2 minuts well. Than one servo turns off.

If the motors are fighting each other then it sounds like some sort of homing/squaring problem.

mh makes sense but there is nothing to hear. Maybe they aren't working against each other. It could be possible that only one motor is truly working and the other one just runs behind the Motor.

When I close the Loop in Linux nothing works maybe because the internal loop isn't tuned well enough.

I'm sure I have to tune they driver with the Leadshine software.

so you suggest tuning the Y-Axis drivers via leadshinesoftware and then try again with linux?

Jasper 3 wrote: Maybe they aren't working against each other. It could be possible that only one motor is truly working and the other one just runs behind the Motor.

I think you need to be sure about this. Can you measure the motor currents (if they are equal and opposite then they are probably fighting each other).
If there is a belt reduction, can you feel the belt tension?