Adjusting the PRS Z-Axis Bearings • October 17, 2016
© Copyright 2016 ShopBot Tools, Inc.
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How to Adjust the Z-Axis
All adjustments take place on the front face of the PRS Z-axis. Note that the steps to adjust the left
and right sides differ in the direction the wrench is turned.
There are five bearings on each side of the Z-axis - three concentric, alternating with two eccentric.
The concentric bearings are in line and need no adjustment. The 2nd and 4th bearings from the top
are the eccentric bearings and may be adjusted. Slide the flat bar wrench (available from ShopBot
if necessary) between the bearing block and the captured rail until the wrench engages one of the
eccentric bearings. Use the pictures above for reference (Left or Right, facing the Z-axis) to loosen or
tighten the bearings.
To Tighten-
• Do not over-tighten. If bearings are forced completely around, it may cause premature failure, loss
of position, or damage to the inside of the captured rail. Tighten only until slight resistance is felt
on the finger tips, then check results. Repeat if necessary. Because the bearing is quite smooth, it
may feel that it is still loose when a finger is gliding over the bearing. Consider marking the bearing
with a small dot for a visual indication.
• Follow the direction of the arrows in the pictures depending on which side of the Z-axis is being
adjusted. This allows for tightening of the bearings without loosening the nut that holds the eccen-
tric bearing.
• Tighten the bearing until the top or lower bearing stops spinning freely or the Z-axis does not move
laterally.
