International: 269-553-2557
Specialist in on-site
spindle taper seat grinding
for repair and restoration of
precision to your machine spindle
Gunn Machine & Tool Co.
Gunn Machine & Tool Co.
Gunn Machine & Tool Co.
Gunn Machine & Tool Co.
Gunn Machine & Tool Co.

Service Info

In-Place Spindle Taper Grinding:

Gunn Machine & Tool Company can restore the precision and accuracy of machine spindle taper seats, on-site. We use special precision equipment, designed and built by us, for this purpose. Our machines feature a set up gage, which is indicated in to your machine’s spindle, setting the proper geometry for grinding the seat, on taper, regardless of the machines alignments. Rotating the machine spindle, as we grind, ensures the seat will be concentric to the spindle’s rotation within its bearing center line, just as in the machines normal operation. This method eliminates the error of tolerance stacked up upon assembly and is the most accurate method of grinding the taper seat true to spindle rotation. We have used this method on new spindles, for machine and spindle manufacturers, when closer tolerances than the norm, are required by their customers.


  1. Inspection of spindle prior to grinding. Visually inspect for damage. Determine the amount of contact area, using precision taper gage and bluing. Test for run out, using precision test bar and indicator. Test drawbar clamping pressure, using Drawforce test gage.
  2. Set up and grind taper seat for proper contact and runout. In process inspections to ensure minimal material is removed.
  3. Final inspection of contact, runout, and drawbar clamping pressure. All inspections are documented and discussed with customer. Inspection report is presented to customer.

Contact us for CNC repair.