CNCKeith's "How to measure Backlash" Method. Video

[cnckeith]

CNCKeith's "How to measure Backlash" Method.



Centroid CNC backlash compensation is a feature used in CNC (Computer Numerical Control) machines to improve accuracy and precision during machining operations. Backlash refers to the small amount of play or lost motion that occurs in mechanical systems, like the ballscrew support bearings, ball nut connections, axis motor pulleys, or other components of a CNC machine, when the direction of movement changes. For example, when a motor reverses direction, there can be a slight delay or looseness before the tool or workpiece actually begins moving in the new direction. This can lead to errors in positioning and affect the quality of the machined part.
Centroid, incorporates backlash compensation into its CNC12 software and controllers to counteract this issue. The user enters the amount of backlash in the machine—typically in units like thousandths of an inch or millimeters—and then CNC12 automatically adjusts the movement commands to account for it. Essentially, when the machine changes direction, the controller adds extra movement to "take up" the slack before proceeding with the programmed path. This ensures the tool follows the intended trajectory more accurately.
In practice, backlash compensation is set up during machine calibration. The operator or technician might run tests to determine the backlash in each axis (like X, Y, or Z), and those values are entered into the Centroid control system. Once configured, the compensation runs seamlessly in the background, making real-time adjustments as the machine operates.

[cnckeith]

i copied this post over from the Acorn forum.

[Snap-On Phil]

Nice video, found this very informative.

[Houseman303]

I have a problem with the backlash function. I entered the measured values, saved them and shut down the control completely and restarted it. When homing the axes, it stopped after Z. Error X axis position error. Turned the machine off again and restarted it. Now immediately the Z axis position error. Am I doing something wrong or is there an error in version 5.06? OAK control.

I only wanted to update the software when TCP is available for xyza or when I no longer have to rely on the Probe app for tool measurement and workpiece measurement. I am not a fan of external program extensions in the software. So far, version 5.06 is running and they always say, never touch a running system.

The machine runs again without problems if I deactivate the backlash function and restart the machine.

[cncsnw]

It is unlikely that testing and adjusting backlash compensation has anything to do with the inability to move your X axis.

Use the yellow jog keys, in Slow, Continuous mode, to test each axis. Don't try to home the machine; just try to jog the axes, taking care to stay off of the limits.

Evidently your Z axis is working. Is your Y axis working? Does the X axis fail to move in either direction? Or does it move one way, but not the other?

Note that, after any "410 ... position error" stall, you will have to press and release emergency stop or the VCP reset button to clear the fault, before you can try to move any axes again.

If it is only the X axis that fails to move, is there any indication on the servo amplifier to tell you why it is failing?

[Houseman303]

without backlash function the machine has been running for a year without any errors

[cnckeith]

without backlash function the machine has been running for a year without any errors

great.

[Houseman303]

without backlash function the machine has been running for a year without any errors

great.

Keith, that doesn't help me. I'd really like to use the backlash feature. I think I even paid for it, if I'm not mistaken.

[cnckeith]

without backlash function the machine has been running for a year without any errors

great.

Keith, that doesn't help me. I'd really like to use the backlash feature. I think I even paid for it, if I'm not mistaken.

hi, i'm here to help.
i'm not sure what your question is!

[centroid467]

without backlash function the machine has been running for a year without any errors

great.

Keith, that doesn't help me. I'd really like to use the backlash feature. I think I even paid for it, if I'm not mistaken.

I strongly suggest trying what cncsnw posted in response to your post about this issue and reporting back the results. I do not believe we are aware of any issues in CNC12 V5.06 that would have this effect.