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Specialist in on-site, spindle taper grinding for repair and restoration of precision

Repair of Face Drive Keys


Gunn Machine & Tool Co. can, in some cases, repair the damaged spindle drive keys without spindle disassembly, on site. However, in some cases the spindle would have to be removed.

The process depends several factors:

1) If the keys integral to the spindle or separate and located in a keyway or pocket.

2) The size of the spindle taper.

3) The top spindle R.P.M.

4) Machine type, make and model.


In most cases, machines such as Horizontal Boring Mills with NMTB, CAT, or BT tapers, can be repaired on-site. This is done by machining the keyway, in-place. We use our special equipment to machine the keyway as needed and make new step keys to fit.


In the case of integral keys, there are different ways to repair. The spindle face can be altered to accept new keys, by machining pockets which will locate new keys, that are then held in by screws. Careful consideration is given in choosing a method of repair that best suits the application


In high speed spindles, that require a high degree of balance, we prefer the spindle be removed.  We can than make sure the balance of the spindle is not changed.

Call now for immediate attention 1-800-859-7979