Unisaw Bearing Replacement
by Jesper Gronvaldt
Formatted by Loren Hutchinson


[Unisaw]Replacing the bearings on Delta's Unisaw is not covered in the manuals, but has to be done sooner or later. This is well within the capabilities of any woodworker with a little mechanical skill, and does not require any real special tools. The specific model described here is a Delta 36-812 built in 1994 - sold as a Model 36-830.

This saw has been working in my shop for five years, and was starting to rattle a bit, although there was not yet any sign of wobble in the blade. I decided to disassemble the arbor and replace the bearings and anything else I found wanting attention.

The numbers in brackets refer to Delta's parts drawing CS-4K-10 (Rev 3-15-93)

You will need the following before you start:

  • 7/8" socket and open-ended wrenches, a really skinny 7/8" open-ended is useful for assembly.
  • 5/32" hex wrench.
  • Hammer, block of wood and a drift or screwdriver.
  • Bearing puller.
  • 8" long piece of ¾" copper tubing.
  • Two Bearings (103) 40 mm x 17 mm x 12 mm wide sealed ball bearings #6203. Standard bearings are fine, there is nothing special about these bearings.

Note: All the threads are right hand threads, except the arbor nut holding the blade.

Disassembly:

  1. Follow the Delta instructions for removing the belts - remember to unplug the saw.
  2. Remove the blade and re-install the flange and flange nut.
  3. Vacuum out the sawdust from inside the saw at this point - it makes it much easier to find the small parts later when they fall off the shaft.
  4. Use a 7/8" open-ended wrench to hold on to the flange nut, and use a 7/8" socket to remove the bearing nut (110) from the shaft.
  5. Loosen the two hex socket screws (107) in the arbor pulley (106) and use a drift or long screwdriver to drive the shaft out of the rear bearing (103). The whole shaft with the front bearing will come out, and you can catch the pulley, the bearing load spring (104) and the two bearing spacers (105) as the shaft comes out. The lock washer (109) was not installed on my saw, and is not really needed.
  6. Use a drift - or spanner if you have it - to unscrew the spanner nut holding in the rear bearing, and remove the bearing.
  7. Remove the front bearing from the shaft with a bearing puller.
  8. Check and clean everything.

If the bearings were tight on the arbor (101) - and the arbor is not scored or otherwise damaged - everything except the bearings is re-useable. If the inner bearing races were loose on the arbor, you will need to replace the arbor.

Assembly:

The bearings are interference fit on the shaft. If you do not have an arbor press, you need to help shrink the shaft and expand the bearings a bit to make assembly easier. Put the shaft in the freezer for an hour, and heat one bearing in an oven set to 150.F (70.C) at the same time.

  1. Support the shaft in a vice, and drive the bearing onto the shaft, using the copper pipe to drive only on the inner race. If you are a little too enthusiastic, and the seals pop out of the races, no harm done, simply press them back with a putty knife till they snap in place.
  2. Now you can re-assemble everything in the opposite order it came off. Note that the bearing load spring goes between the front bearing and the front bearing housing in the arbor bracket.
  3. Tighten the bearing nut, which will clamp the inner races, the pulley and the spacers together. Re-install the spanner nut, which will clamp the rear bearing in the housing. Any clearance and expansion/contraction is taken up by the bearing load spring between the front bearing outer race and the front bearing housing in the arbor bracket.
  4. Re-assemble the belts as described by Delta after tightening the pulley set screws. Re-install the blade, and check adjustment of the distance gauge on the fence.

Except for working in cramped quarters inside the saw, there is nothing difficult about this job. There is no need to align the belts if they were in alignment to begin with, it all happens automatically.

Remember that a bearing and the bearing load spring go on the blade end of the shaft before the assembly. Then a spacer, the pulley and another spacer. Assemble in arbor bracket, and add the last bearing, bearing nut and spanner nut from the motor end.

This is two to three hours' worth of work, and your saw is ready for several more years.


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© 2003 by Ellis Walentine by special arrangement with Wayne Miller of Badger Pond. All rights reserved.
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