Calibrating Axis Straightness
- deepfritz7
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24 Nov 2013 03:34 #41136
by deepfritz7
Calibrating Axis Straightness was created by deepfritz7
Hi Folks!
I was wondering if LinuxCNC offers the capability to compensate for geometric errors of the machine axes?
For example on my mill: I posses the measurment equipment to measure the straightness of the 2m long X-Axis. I can measure the deviation from the ideal straight to the actual machine position. LinuxCNC could easily compensate this error using the Y-Axis, which is perpendicular to the X-Axis. Is that possible? And if not, how could i archive this ? I thought of programming a little tool for post-processing the G-Gode in order to compensate for the measured position errors, when LinuxCNC alone is not capable of doing this.
What do you guys think of this ?
I just know that on big professional cnc machines, the controllers allows to calibrate for spindle pitch errors, straightness errors, squareness errors and so on..
Greetings
I was wondering if LinuxCNC offers the capability to compensate for geometric errors of the machine axes?
For example on my mill: I posses the measurment equipment to measure the straightness of the 2m long X-Axis. I can measure the deviation from the ideal straight to the actual machine position. LinuxCNC could easily compensate this error using the Y-Axis, which is perpendicular to the X-Axis. Is that possible? And if not, how could i archive this ? I thought of programming a little tool for post-processing the G-Gode in order to compensate for the measured position errors, when LinuxCNC alone is not capable of doing this.
What do you guys think of this ?
I just know that on big professional cnc machines, the controllers allows to calibrate for spindle pitch errors, straightness errors, squareness errors and so on..
Greetings
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24 Nov 2013 20:47 #41146
by Rick G
Replied by Rick G on topic Calibrating Axis Straightness
You might want to look here...
wiki.linuxcnc.org/cgi-bin/wiki.pl?Kinematics
Also search this forum a bit as it seems to me that this was discussed here not that long ago.
Rick G
wiki.linuxcnc.org/cgi-bin/wiki.pl?Kinematics
Also search this forum a bit as it seems to me that this was discussed here not that long ago.
Rick G
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25 Nov 2013 07:15 #41152
by andypugh
Maybe....
LinuxCNC has built-in ways to compensate for screw-pitch errors, and there is a kinematics module that can compensate for out-of-square error.
But what you want to do is offset Y dependent on X and offset X dependent on Y.
I think you could so this with the lincurve HAL component. Pass X into the table and add the output to the Y value before passing it to the stepgen or servo.
If the corrections are significant then you might have problems with the f-error, so you should use the "offset" HAL component to add the offset to the motor position, then subtract it from the feedback position.
www.linuxcnc.org/docs/devel/html/man/man9/lincurve.9.html
www.linuxcnc.org/docs/html/man/man9/offset.9.html
Lincurve only exists in the development version of LinuxCNC, but it would be easy to copy the file across and compile/install it on your system using comp:
www.linuxcnc.org/docs/devel/html/hal/comp.html#_compiling
Replied by andypugh on topic Calibrating Axis Straightness
I was wondering if LinuxCNC offers the capability to compensate for geometric errors of the machine axes?
Maybe....
LinuxCNC has built-in ways to compensate for screw-pitch errors, and there is a kinematics module that can compensate for out-of-square error.
But what you want to do is offset Y dependent on X and offset X dependent on Y.
I think you could so this with the lincurve HAL component. Pass X into the table and add the output to the Y value before passing it to the stepgen or servo.
If the corrections are significant then you might have problems with the f-error, so you should use the "offset" HAL component to add the offset to the motor position, then subtract it from the feedback position.
www.linuxcnc.org/docs/devel/html/man/man9/lincurve.9.html
www.linuxcnc.org/docs/html/man/man9/offset.9.html
Lincurve only exists in the development version of LinuxCNC, but it would be easy to copy the file across and compile/install it on your system using comp:
www.linuxcnc.org/docs/devel/html/hal/comp.html#_compiling
The following user(s) said Thank You: finnstrom
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25 Nov 2013 20:04 #41156
by Rick G
Replied by Rick G on topic Calibrating Axis Straightness
Might want to look at millkins...
wiki.linuxcnc.org/cgi-bin/wiki.pl?Contri...y_XY_skew_correction
Rick G
wiki.linuxcnc.org/cgi-bin/wiki.pl?Contri...y_XY_skew_correction
Rick G
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