Johnford DMC-1200 Spindle Repair

Johnford DMC 1200 Spindle Repair



CHALLENGE

Upon initial inspection, the bearings on this Johnford DMC 1200 spindle were noisy when rotated by hand. Bearing spacers were set up for super heavy preload. The rear support bearings were found to be contaminated. Significant damage had occurred to the rear shaft threads.
The outside diameter of the shaft nose had light rubout damage, which we could polish out. Drive dogs (keys) were damaged. The shaft pulley journal OD was previously plated and ground and had some fretting and pits, but was able to be reused. Measurement of the shaft’s 60mm encoder journal OD that the diameter is egged 0/-8µ with an excessive runout of 2-10µ.
The tooling taper ID was previously plated and ground. It was pockmarked with holes in the chrome. Gripper fingers (collet) showed significant wear. Drawbar nut was galled to the shaft threads. The shoulders of the encoder ring and drive pulley were out of parallel alignment.

SOLUTION

We adjusted the shoulders on the encoder ring and drive pulley for correct parallel alignment. No issues were found with the encoder and the customer declined our recommendation to grind, chrome plate & finish grind the 60mm encoder journal OD. We performed a kiss grind to the tooling taper ID to improve surface contact with the tool holder and smooth over visible pitting.

This repair included all new bearings, drive dogs, rear shaft and locking nuts, o-rings & assembly screws. A complete drawbar assembly was also required, including; drawbar shaft & nut, Bellevilles, and gripper assembly.

The spindle passed our rigorous final quality control inspection before being shipped back to the customer.

DETAILED CAUSE OF FAILURE

  • Poor chrome plating from another rebuilders previous repair

  • Drive dog and rub out damage

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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 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