Tuesday, 20 February 2018

Dewalt DW738 - replacing the drive wheel and upper wheel

Unfortunately the rubber tyres on this bandsaw are not capable of being replaced and the wear on the upper wheel after nearly 10 years is considerable. Spare parts are still available (2018) for this machine so I decided to buy a new set of wheels to prolong the life of the bandsaw.

The wheels come as a full assembly complete with bearings, new rubber tyres and are a simply bolt off bolt on arrangement. I also bought a new set of rubbing bearings as the old ones had considerable wear.

The procedure to do this is:

  • Open the access door
  • vacuum any residue from previous operations.
  • Remove the table
  • Remove the blade after loosening the upper wheel tensioner

I also removed the upper rack and pinion assembly complete with bearing assembly. While I was at it I removed the lower bearing assembly.

Slacken the motor

The lower drive wheel removal first of all required the drive belt to be slackened. There is a socket head screw holding the motor in place. Slackening that off enables the tension to be slackened.

Remove nut and washer

Next there is a nut and washer to be removed from the axle on the enclosure side.
Turn the key clockwise

There is a left hand thread holding the shaft to the machine frame. Turning the socket head in the shaft with an allen key loosens the shaft.
Ultimately the wheel assembly comes off.

The new one is installed with a reversal of the above process.

The upper wheel is easy to remove but you do have to be aware of parts that can fall out.
Old upper wheel assembly in situ

Loosen the tension knob until it disengages from the central screw shaft.
There are 2 washers and a thrust bearing at the top that can fall on the floor so be aware.
The wheel assembly can then be slid down the guides in the frame.
Note that the washer is in the frame

The spring will also come loose. There is another washer under this spring.
View showing the coach bolt in place on the wheel assembly

Remove the central adjustment shaft from the wheel assembly. This is just a square headed coach bolt.
New wheel on the left
Old worn out wheel on the right

As can be seen here the old and new wheels so a radical difference in wear.

Assembly is a reverse of disassembly.

Note the order of the components in the tensioner

There is a washer, thrust bearing and another washer before the spring

This time you have to carefully place the spring, washers and thrust bearing over the shaft before engaging the nut. You also have to make sure the square headed coach bolt is engaged and the wheel assembly slid between the guideways on the frame.

It is fiddly but with care is easy to do.

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