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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