Ball Bearing 605040-27

Remove the motor from the gear case, Remove motor leads from the switch, remove the the brushes. Remove the back motor cap. Remove the screws from the motor housing, then using a mallet tap on the gearcase to separate the housings. Remove the armature. Remove the retaining rings. I have a friend that let me use his arbor press to remove and install the bearings. (You can try a tool repair shop for this also.) Remove the old sleeve from the housing. and install the new one. Then install all of the parts in reverse order.

Removed the armature
Pulled the old bearings
Installed new bearings
Polished the commutator
Reinstalled the armature
Reinstalled the case
Made a test run to verify the repair

Remove the standing head Remove the Bearing Carrier Replace the bearing put the burden Carrier back on, Screw to sanding head back on with 4 screws

The first problem was that the bearing sent were not correct. Outer diameter was 35 mm, rather than 40 mm required. My Black and Decker saw was model # 7740/3421 Type 2. The bearing required was 17mm id, 40mm OD, 12 mm thickness. The bearings sent had a 35 mm OD. Strangely I bought the correct bearings from Amazon, 2 for $21. At least two other parts houses had the correct size identified.

Replacement of these bearings is difficult, required pressing the old bearings off and pressing new ones on. It is not a hard interference fit, but challenging, because of access and difficulty find a sufficiently strong spot to set the puller. the interference fit to shaft (ID) requires hundreds of lbs force but the outside fit to housing is very easy, 50#. The major problem was tying to get the forward and rear section of the motor body apart. There are two roughly 1/4" alignment steel pins hard driven into the aluminum castings and these had corroded offering tremendous resistance to movement. I used JD weld metal filled epoxy to put 1/4" x 1/2" x 1" tabs on the side of the housing. I drilled the tabs and installed short 1/4 x 21 cap screws to provide a grip for the gear puller. After what seemed like a very high force applied, they broke loose and I managed to get the rotor out. I used a rubber hammer to drive the rotor shaft out of the forward housing and a gear puller to pull off the rear bearing. The rear bearing shaft was carefully cleaned, was lubricated with an anti corrosion spray and the bearing driven on using a deep 3/8 drive socket. The forward bearing was, after careful cleaning of the socket, tapped into place with a piece of 1/2" high density poly and a rubber hammer. The rotor and shaft were then pushed through the forward bearing and pulled into place with a pipe spacer and the reverse threaded brass nut that hold the blade on. The rear section bearing fits fairly easily into rear housing and is tapped home with the guidance pins and rubber hammer. The long bolts are put in place to hole the motor together. Hopefully these bearings will last another 50 years, much longer than I will.

I did not return the incorrect bearings because they are worth $8 total and postage would be $12. The correct original bearing number for front and back is 330003-16. The type 1 motor had different bearing fore and aft and perhaps this was the issue.

I would suggest on items like bearings, it would save a lot of time if you provided the three dimensions. Of all the websites I looked at, only one provided the dimensions. I then had to trace two more current replacement model bearings and found the right ones by typing in the current model number on Amazon. I probably had 12 man hours in finding the right bearings. Prices on the web varied from $1.86 to $27 for what appeared to be the exact same bearing.

R. Dryden PE

1. Flip saw over and remove the four screws that hold the plastic case onto the gear box. You may need to set the saw blade to 45 degrees to get good access
2. Remember to unplug the saw...
3. Remove the plastic case by pulling straight back
4. Remove the armature assembly by pulling straight back. You may need to rock it back and forth.
5. Remove the bearing using a bearing puller
6. Press the new bearing into place.
7. Put everything back in reverse order.
8. Say a prayer and then start the motor

took the sander apart to get to both bearings on the motor. used a puller to pull bearings off shaft. put it back together. The reason I fixed this sander is its one of the old 1/2 sheet vibrator sanders that you can't buy anymore, but I use them a lot for my wood working projects.

Most difficult part was removing the bearing inner race because it was really stuck so cut it through diagonally with dremel cut off wheel carefully not to damage the shaft and pulled it away with pliers. All the rest went easy enough

Checked out problem, took sander apart, remove bad parts and install new parts after they arrived.

Remove side cover
Remove belt
Remove drive gears
Remove main sub assy including motor
Carefully remove old bearings
Assemble