SPS Spindle
Onsite Taper
Grinding

Call 866-868-6761 or email us

Spindle Taper Grinding Done Onsite at Your Facility

SPS Spindle provides an onsite service to restore the precision tool holding taper on your machine tool spindle.  Utilizing our custom designed CNC Spindle Taper Grinding system, an SPS technician can grind the taper to your required specification without removing the spindle from the machine.  Our onsite taper grinding specialist will be at your facility as quickly as possible.  We have all of the necessary skills, taper gauging, and tools to grind advanced CNC spindles and high-speed precision spindles.

Contact SPS

Our Process:

  • Complete Spindle Assessment Prior to Taper Grinding
  • Vibration Analysis
  • Drawbar Retention Force
  • Detailed Taper Inspection
  • Runout
  • Taper Contact
  • Test Bar Measurements
  • Tooling Inspection
  • Grinder Setup
  • Grinding in Place of the ID Taper
  • Grinding in Place of the Spindle Face (BIG Plus® & HSK only)
  • Constant Monitoring and Measurements Taken Throughout Grinding Process
  • Complete Quality Control Inspection After Grind
  • Drawbar Retention Force
  • Detailed Taper Inspection
  • Runout
  • Taper Contact
  • Test Bar Measurements


Our comprehensive spindle taper grinding services are handled by Phil Marmo, who travels across the U.S. servicing customers. To learn where Phil is going to be next and how quickly he can be at your facility to handle your taper grinding needs, call 866-868-6761 to schedule an appointment. WATCH PHIL’S VIDEO

CAT, BT, BIG PLUS®, HSK, AND MORE!

Our onsite service is available on all horizontal and vertical machining centers. Our comprehensive CNC Spindle Taper Grinding services are backed by over 25 years in the high speed spindle rebuilding industry. We always strive to keep your machine’s downtime to an absolute minimum.

The spindle taper grinding service is performed using the rotation of the spindle shaft within its own bearings. Therefore, it is critical that the condition of the spindle bearings and the complete rotating assembly be good in order to achieve the best results. To provide our customers with the most efficient service job, each SPS Onsite Taper Grind customer will be provided with a pre-grind checklist of instructions prior to our arrival.

Frequently Asked Questions

Q. How much material is removed from the spindle taper during a kiss grind?

A kiss grind removes only a very small amount of material from the spindle taper—just enough to restore proper toolholder contact without unnecessarily reducing the taper’s life. In many cases, the imperfections are not deep wear but raised material caused by toolholder fretting, minor damage, or debris transferred to the spindle taper.

During the spindle taper grinding process, SPS uses precision equipment to remove only the high spots while continuously monitoring material removal. Once the taper achieves approximately 70% or greater contact, we verify spindle runout to ensure the taper is performing within acceptable tolerances. If additional grinding could further improve contact, we discuss the options with the customer before removing any more material.

Our goal is always to restore spindle accuracy and maximize spindle life while removing the least amount of material possible.

Q. Will grinding the spindle taper affect my drawbar force?

In most cases, no. A properly performed spindle taper grind does not significantly affect drawbar force. Before any grinding begins, SPS measures the drawbar force to establish a baseline. After the spindle taper has been restored, we measure it again to verify that it remains within specification.

If we find that the spindle taper damage was caused by insufficient drawbar force, simply grinding the taper will not solve the underlying problem. A weak or worn drawbar can prevent the toolholder from seating correctly, leading to poor taper contact, fretting, chatter, increased runout, and premature spindle wear.

When low drawbar force is identified, we recommend repairing or replacing the drawbar before returning the machine to production. This helps protect your newly restored spindle taper, ensures proper tool retention, and maximizes machining accuracy and spindle life.

At SPS, our goal is not just to restore the spindle taper, but to identify and address the root cause of the damage so the problem does not return.