Cincinnati Sabre 1000 loss of preload causes spindle to fail


Possible cause of failure:
Front and rear bearings failed from contamination that caused lack of preload to the bearings.
Inner bearing spacer spun on shaft causing damage.
Rear shaft journal has 8-10 microns of runout and has a rubout band caused by the inner spacer.
Front shaft journal has rubout damage caused by the inner spacer.
Shaft taper has 40-60 microns of runout, slightly bell mouthed, taper gauge sits below gauge line.
Where the bellevilles ride on the shaft tail is severely worn.
Drive dog is worn.
Drive pulley teeth are worn.


Recommended action:
Clean, inspect overall dimensions.
Grind, chrome plate and finish grind the front and rear shaft journals.
Grind, chrome plate and finish grind the CT 40 taper.
Grind, chrome plate and finish grind the shaft tail.
Manufacture a new inner bearing spacer.
Replace bearings, gripper balls, bellevilles, lock washer, seals, orings, drive dog and drive pulley.
Adjust preload, balance, assemble and break in. Final quality control inspection.


  • This is the inside of the front cover. Notice the contamination throughout the cover porting.

  • Picture of the contamination present in the angular contact bearings

  • Damage to the shaft from the inner spacers spinning on the shaft.

  • Damaged taper

  • The new pulley being balance on our Schenck balancing equipment. This equipment lets us component balance the rotating parts of the spindle before the spindle is assembled. This step enables us to make very small adjustments during the final trim balance of the spindle. Other rebuilders often skip this step to save time which means they remove large amounts of material on the final test run. When that is done they sometimes are not removing the material exactly were it is needed as they can no longer access the area so they need to compensate with larger removal of material.

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Repair History - Here are examples of similar spindle repairs that may contain additional information that will help you. If you have additional questions, please contact us.

I really didn’t expect this; You guys really pulled it off! My many thanks to Sandy, Louis and your outstanding crew for helping us get back into production.

Dan Eaton, Taylor Metalworks

Lou all in all everything is running good. Just had a call from Sandy just the other day, its funny great minds think alike. Its great not to be sending spindles out on a regular basis since you addressed my problems, but I know they will still be coming sooner or later. Never a problem when we get them back , run better than new. Hope everything is ok there. Please tell everyone there that we here appreciate everything that you do to keep us up and running and the quick turnarounds. Have delt with the rest now deal with the best. Have a great week end and up and coming holiday.

Northland Customer

Thank you Debbie just received spindle today and WOW ! what a nice job. Can’t wait to use it. Thank the Northland team for us for a job well done 

Northland Customer

Both of the spindles that you repaired are on the machines and running great. We don’t have any spares for those grinders. We probably will not be purchasing a spare, as you have been able to turn around the repairs quickly and the price of a spare is cost prohibitive.

Northland Customer

I am writing to thank Northland Tool for going the extra mile and saving my company from expensive machine downtime and expensive repairs. We have always sent our Chiron spindles for repair as a shaft with bearings. None of our previous rebuilders pointed out the bearing fretting or the fact that the housing in the machine was out of tolerance and causing premature failure to the spindles. After Northland fixed the housings the spindles have never sounded as good or run as well! Great job guys!

Northland Customer

The detailed cause of failure reports and the expert technical advice that Northland Tool provides is bar none the best I have ever seen. We struggled to keep two of our large our milling spindles running for longer than 6 to 12 months. Northland Tools evaluation showed that the hydraulic nuts were not holding the assembly together causing premature spindle failure. We discussed this in detail and mutually decided to modify the spindle shaft to prevent this from occurring again. The first spindle we performed this on is still in the machine running like new after 3 years. That’s over three times the life of previous repairs and it’s still going strong. Easily over $40,000.00 of savings so far on that one machine and counting.

Northland Customer

Your people go above and beyond the call of duty when it comes to spindle repair. When we had difficulty with the spindle installation and we were able to talk directly to a spindle technician that helped us troubleshoot the issue it helped us out of a bind. We have sent several spindles to you and have nothing but great things to say.

Northland Customer

Thank you for your attention with my quick turn spindle repair. Your status updates allowed me to plan around machine downtime and I now know that you deliver on your promises. In the past other spindle repair vendors talked a big game and consistently failed to deliver. You not only delivered my spindle before the due date but you kept me informed throughout the entire repair process.

Northland Customer

You performed a miracle with my BIG PLUS spindle. After crashing the spindle severely damaging the taper we found that a replacement spindle was not only cost prohibitive but had a long delivery. Your repair was a fraction of the cost of new and you never would know that the spindle was damaged to the extent it was.

Northland Customer