Background
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If you decide to make an adjustment, be careful to avoid assuming the error. It could be attributed to a specific problem, or from the combined effect of several problems.
Example
The Z-axis gib is too loose, which causes the spindle head to tilt slightly downward toward the column. It's easy to assume that the issue is with the column and base connection (often referred to as tram), and make an adjustment by inserting shims between the column and base. Instead of correcting the real issue, though, this adjustment causes the column to slant back to correct for the head leaning down. Now, the machine is running in a slight parallelogram — and it still has a loose spindle head.
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For information, see "About Angular Contact Bearing Pre-Load".
Required Tools
To Adjust the Angular Contact Bearing Pre-Load
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Under typical use, no adjustment of pinned connections should be necessary. In the event of a hard crash, you can use shims to make minor alignment adjustments between pinned components. Small adjustments (less than 0.010 inches) will generally not require a full disassembly of the pinned connection. In these cases, the alignment dowels can be left in place, and the shims can be inserted into a small opening created by loosening the bolted connections.
Looking for more information?
This is a section of the PCNC 440 operator's manual. To view the whole manual, go to Tormach document UM10372.
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Backlash Compensation
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Backlash compensation is only available on Pathpilot version 2.2 and above for all machines |
Backlash compensation is used after the gib and angular contact bearings have been adjusted to less than .001” of lost motion.
Use the “ADMIN SET_AXIS_BACKLASH” command in the MDI line to apply backlash compensation. Use X/Y/Z following the command to indicate the axis to apply backlash compensation to and a number following the axis to indicate the amount of compensation to apply. Compensation is limited to .005” per axis.
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The “ADMIN GET_AXIS_BACKLASH” command will display the current amount of backlash for each axis. The “ADMIN RESET_AXIS_BACKLASH” command will reset the backlash values of all axes to 0.
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Note: There is no backlash compensation for the A axis.