Backlash?

[mgamber]

Are there any settings or adjustments that could cause reverse backlash? Meaning that when I change directions, I GAIN position?

[CNCnUtZ]

Originally posted by mgamber Are there any settings or adjustments that could cause reverse backlash? Meaning that when I change directions, I GAIN position?

Ive been a proud Gecko user for a few years, and Ive yet to see any settings on the drives that would cause that.

What drivers are you using?
What exactly is the problem........?

Details of your CNC, ect?

[HuFlungDung]

Are these stepper drives? I wouldn't trust a stepper without encoder feedback, because you can never tell if some kind of high load (cutter load or machine binding) causes your machine to lose a step or two. So, it sounds like the machine has not actually completed the previous move (due to load) and then, because it lacks a feedback loop, then it continues to make a full length move in the opposite direction.

[balsaman]

A backlash setting in the software that too high will cause that.

Huflungdung is correct if your machine is missing steps in one diretion it will act like it's going too far in the other.

As far as closed loop steppers, my machine is open loop and doesn't miss steps. If it's set up correctly you can run all day without missing steps.

What software do you use?

Eric

[mgamber]

servo's, not steppers.

Mach1

It appears that the machine only does this without a load. I am wondering if it is enertia.

[CNCnUtZ]

Sounds like you are running acme screws for the drives on each axis(or some real lousy ballscrews)

If I were you and I wanted cuts to be as precise as possible, Id change over to ballscrews.

[HuFlungDung]

Originally posted by mgamber servo's, not steppers. Mach1 It appears that the machine only does this without a load. I am wondering if it is enertia.

If your servo drives have encoder feedback, this would be a very strange problem to have. The parts of the machine you can check would be the motor coupling to ballscrew, and the encoder coupling to the motor or screw. Any looseness here could cause a misposition.

Servo loops cannot normally tolerate any misposition, because the feedback from the encoder forces a voltage differential that should force the motor to a position that minimizes the difference between the commanded position and the actual position. However, if a circuit board fails, anything becomes possible.

[routerman]

Pulse timing on a gecko is sensitive. Check the setup times