Mastercraft 9" Band Saw (055-6748-6) -- Rear Blade Support Bearing Failure

The rear blade support bearings lead a hard life, and both bearings on my machine have lost their outer seals. The lower bearing, showered as it is with sawdust, has all but seized up.

The saw has an upper rear blade support bearing (two views).

And a lower rear blade support bearing (two views).

                                                  

Replacement Bearings

The bearings are No. 606RS -- 6mm bore x 17mm O.D. x 6mm width, sealed both sides. Replacements are readily available from Amazon.

Lower Bearing Replacement

• Release blade tension and get the blade out of the way.
• With a 4mm hex key, loosen off the setscrew securing the bearing's mounting post. (A hole in the front of the saw's frame gives access to the setscrew's head.) Remove the post/bearing assembly.
• With a 4mm hex key, remove the M5 x 16mm screw fastening the bearing to the post. Mind the flat washers on either side of the bearing.
• Replace the bearing. Reinstall the post/bearing assembly loosely.
• Reinstall the blade and spin it manually to reestablish blade tracking. The back of the blade should be just touching the upper rear blade support bearing.
• Adjust the lower post/bearing assembly so that the blade is just touching the lower rear blade support bearing.
• Lock the post/bearing assembly in place with the setscrew.

Upper Bearing Replacement

The upper bearing's mounting post is different from that of the lower bearing -- it's not readily removable from the saw's frame with its bearing attached. Proceed as follows.

• Have the blade tensioned and running true. The back of the blade should be just touching the lower rear blade support bearing.
• Swing open the black shield concealing the upper blade guide.
• With a 4mm hex key, loosen off the screw fastening the bearing's mounting post to the saw's frame.
• Slide the post/bearing assembly back as far as it will go. The bearing is now fully accessible for removal.
• With a 4mm hex key, remove the M5 x 16mm screw fastening the bearing to the post. Mind the flat washers on either side of the bearing.
• Replace the bearing.
• Move the bearing's mounting post forward so the bearing just contacts the rear of the blade.
• Lock the post/bearing/assembly in place with the screw.

Note:

The saw's Instruction Manual calls for a 0.002" gap between the bearings and the rear of the blade. Such adjustment strikes me as difficult, pointless and needless. I simply adjust the bearings so that they are in contact with the rear of the blade.

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