Cincinnati FTV850-3700 Spindle Repair

Cincinnati FTV850-3700 Spindle Repair

The Cincinnati FTV850-3700 is a large CNC vertical machining center.  It can come fitted with this oil mist lubricated and pulley driven spindle that is capable of running up to 6,000 rpm.

Cincinnati FTV850-3700 Spindle Repair


Our customer sent in this Cincinnati FTV850-3700 spindle stating they were getting low drawbar pullforce.  Once the spindle arrived at Northland Tool we completed a full disassembly and evaluation.

Cincinnati FTV850-3700 Spindle Repair

This is what we found:

  • We were only seeing about 1300Lbs of draw bar force. (Print specs 3300 Lbs.)
  • The inside of the shaft was heavily corroded and rusted, one of the factors in the low force.
  • The draw bar shaft was heavily corroded and we recommended it be replaced. (Pic 3)
  • Ball cage was also heavily worn and needed to be replaced.
  • The ( Shaft ID ) housing for the brass ball cage was corroded (Pic 2)
  • All four bearings were worn and the rear bearing grease was contaminated with a dark brown grease (Pic 1)
  • ID 50 Taper had poor contact and measured “AT wrong” on our air gauge
  • The Bellevilles were worn
  • The OD bearing journals had score marks



The following actions were performed on this Cincinnati FTV850-3700 spindle:

  • Replace Bolts, O-rings, Bearings, Bellevilles, Belt, Brass ball cage, and Draw bar
  • Grind-Plate-Grind (GPG) ID 50 taper due to poor contact, low gap and failing on the air gauge system
  • GPG ball cage housing in rear ID of shaft
  • GPG tail of shaft where Belleville’s pilot due to heavy corrosion
  • Polish OD bearing journals in assmembly



After reassembly of all components, adjusting bearing preload, and undergoing break-in and testing procedures, this spindle passed our final quality inspection before being returned to our customer with a 1-year warranty.


  • Brown grease in bearings (Pic 1)

  • Corrosion inside the shaft (Pic 2)

  • Corrosion on the drawbar (Pic 3)

  • Sludge in the coolant loop

Does your spindle need repair? GET A QUOTE TODAY

More Case Studies

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 your outstanding crew for helping us get back into production.
— Dan Eaton, Taylor Metalworks
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 NTE 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
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