Hardinge VMC 1500XP3 Spindle failed rotary union


Contaminated bearings, leaking rotary union

Hardinge VMC 1500XP3, 8000 RPM, grease bearing lubrication, pulley driven

This vertical machining center spindle arrived completely disassembled, but it was readily apparent that a leaking rotary union had allowed coolant contamination to penetrate the entire spindle interior. Not only were the rear cover & drive pulley heavily corroded, but the grease was mostly washed out of the rear roller bearing and the front quad set of angular contact bearings, plus the drawbar assembly was full of sticky coolant residue as well. When we tested the tool retention force, it was 1300 lbs compared to a minimum spec of 1900 lbs. The light wear we observed on the gripper (collet) fingers may have contributed to this. We also measured runout of 30-40µ at the end of a 9” test bar.


To alleviate the excessive runout, we performed a kiss grind of the tooling taper in-house on one of our Kellenberger grinding machines. We then reassembled the spindle with all new bearings, Bellevilles, o-rings & assembly screws. Our customer opted not to have us install new grippers because they already had a set in good condition left over from a previously-replaced drawbar assembly. We test ran the spindle for 4 hours to break in the new grease while closely monitoring the vibration & thermal characteristics. When our customer received the rebuilt spindle, their 3rd party CNC service technician installed a new rotary union and the replacement gripper set. The rebuilt spindle is now making chips and performing flawlessly.


  • Washed out drawbar

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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