SX3 Spindle Modification

[Old Megawatts]

Since my machine was new, it has never sounded really smooth. I have cleaned, repacked and re-adjusted the bearings several times. I finally decided to make a concentrated effort to make it run smooth. I pulled everything out again and cleaned everything until it was spotless. I removed the top thrust bearing and put it away as I didn't intend to use it again and made a spacer to compensate for the difference. I then ordered a new Timken bearing for the bottom (NTN 32907X, 32907XU) and an angular contact bearing (Consolidated 7006 B 2RS) for the top. I also modified one of the spanner nuts by drilling and tapping for a setscrew. The other spanner nut I put away. The bearings were pressed on the spindle and put back in the quill and adjusted for clearance. Everything was then placed back in the head. After doing so, I realized that it is nearly impossible to get at the spanner nut when it is in the machine. My answer to that was to drill a 1/4" hole in the casting about 1.250" below the top of the head casting behind the bottom panel and tap it for 5/16-18 for a short plug just to keep crap from getting into the electronics. I can now insert a piece of 1/4" drill rod that has been turned on the end to fit into the slots in the spanner nut on the spindle. After backing off the set screw in the spanner I can insert the the rod through the hole and lock the spanner then I can turn the bottom of the spindle to adjust the clearance when needed.
After doing all of this, the machine sounded pretty good but still had a noise in it. This was tracked down to the drive pulley. It is mounted in a single row bearing and the clearance in the bearing allows the inner spline in the pulley to rattle on the OD of the spline on the spindle. I attempted to find a double row bearing to replace the single row without success. After scratching my head for a while I decided to replace the single row with two bearings. The original bearing was a 35 x 62 x 14 and the new bearings are 35 x 62 x 9. By modifying the bearing housing and the pulley shaft they can be installed without making anything new.
After making this modification and installing it the machine sounds beautiful. It was well worth the effort! I am attaching the drawings in pdf formay so most everyone can read and print them.

OM

[Old Megawatts]

Sorry, I forgot to post one of the drawings and to post the number of the replacement bearings on the pulley shaft. They are #16007 2RS.
Sorry about the mixup.

OM

[iGG1e]

Thanks for the information. I've been gathering bearings etc. to do the job and this will help a lot.

A quieter spindle and the possibility to get it under full CNC control - must be dreaming

[cjdavis618]

Thanks for the post Old Megawatts, I have a similar post over in the benchtop forum. I will link this over there so they may also see this option.


Great work, I'm ordering these bearings now for my upper pulley bearing.

Thanks
Chris