Monday 19 February 2018

Dewalt DW738 - Replacing rear thrust bearings

Over time the rear thrust bearing wear out and can be very easily replaced.
The replacement part is a 608-ZZ-EU (608Z) and has the following characteristics:

  • 22mm outside dia
  • 7mm width
  • 8mm inside diameter
  • double metal shields
  • deep groove ball bearing for thrust and load carrying

Set of new bearings and original bearing shaft

They are very cheap and easily available

To replace the bearings you do have to disassemble various parts of the bandsaw

For the lower bearing


  • Remove the table
  • Loosen the grubscrew holding the lower thrust bearing shaft in place.
  • Gently pull out the shaft. Beware that the grubscrew and nut can fall out so temporarily insert a 10mm drill into the hole and tighten the grubscrew.


For the upper bearing


  • Loosen and remove the nyloc nut and washer holding the rack and pinion adjustment knob in place
  • Remove the rack and pinion assembly complete with mounting shaft
Rack and pinion removed from bandsaw

  • Remove two screws holding the blade guard to the rack and pinion
  • Loosen the grub screw holding the upper bearing shaft in place.
  • Gently pull out the shaft. Beware that the grubscrew and nut can fall out so temporarily insert a 10mm drill into the hole and tighten the grubscrew.

Removing the bearing from the shaft

  • Place the shaft into a suitable 11-12mm inside diameter steel tube and insert both into an engineers vise loosely tighten the vise
  • The bearing should be supported by the tube
  • using a 6mm diameter drill drift or nail punch gently hammer the shaft from the bearing.
  • The shaft will fall into the tube
  • The bearing can be discarded

Replacing the new bearing onto the shaft

  • The new bearing works in both directions so orientation is not a problem
  • insert the stepped head of the shaft into the bearing hole. It will not go in as it is an interference fit.
  • Use a small 6mm socket from a 1/4" square drive socket set
  • Place the narrowest end of the socket onto centre of the bearing. It should be no more than the overall diameter of the inner section of the bearing.
  • Holding the shaft bearing and socket together insert it into the engineers vice and gently tighten the jaws

  • Make sure you have safety glasses on
  • Now gently tighten the jaws ensuring you keep the assembly as square as possible
  • The shaft will go into the bearing until it hits the step on the shaft.


Reassembly

Reassembly for both bearing assemblies is a reverse of respective disassembly

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