the Walnut Diary

Because of family schedules, Bet and I spent both Christmas and New Year’s days by ourselves this year, so we used the time to pursue less festive activities than the norm. Today’s task for me was to revive the motor in the photograph, and elderly Delta 3/4 hp 220 motor from a 6″ General jointer. Its user claimed that it would still start the jointer, but when the wood arrived, it would not cut it. I suspected an expired capacitor, but none was to be found. Instead, when I removed the end plate, I found this:

It was a combination mouse nest and shaving accumulation, but the poor motor was plugged. So we took it apart and cleaned it out. Reassembly took longer than the cleaning, but the old Delta was well made from good materials, and it tolerated a good deal of foolishness and still started up when asked. We had to learn the way of thinking of the motor’s builders in order to assemble it. The brushes were like new in a motor older than I am, but putting them back in was a head scratcher until we figured out the point behind a peculiar loop on the wire joining each pair of adjacent brushes. We found that loop was perfect to hold the brushes away from the commutator as we slid the assembly over the bearing. Then on subsequent attempts we discovered that the brushes can be jammed in the “up” position, to be released later to fall into place by a probe through the service ports after the unit is in place.

But replacing the two screws you see on the end of the motor was enough to drive a deacon to drink. The screws had twisted out of a pair of sleeves rather resembling empty .22 cartridges which slotted into their places on the inside of a large washer. Getting them into position and keeping them there was the problem. I decided that a bent and worn fibre/plastic insert was obstructing progress and deserved a visit to the shop floor. Then the assembly went together.

The worst thing about old motors is the length of the leads to the switch box. Connecting wires in tight quarters was aided by good lighting, but my old fingers just aren’t up to the traditional mar connectors with a bronze sleeve and screw, covered by a bakelite protector. Eventually I gave up chasing the little brass screws around the floor and twisted the more recent mars I found on the bench.

Two lengths of uninsulated wire connected the four brushes. I made sure that the long screws which hold the motor together were not touching these wires. Then we took deep breaths and hit the on switch. It started right up and ran smoothly, even though the end plate was a little off. A couple of sharp taps with a hammer rectified that.

Instructions in manuals list the motor installation as the reverse of the removal. We decided that #12 Robertson screws had not been available the last time anybody worked on this jointer, and that was why they used 1/4″ carriage bolts to sandwich the motor feet and two layers of 3/4″ plywood to the thin metal floor of the stand. Four screws and washers pinned the motor to the pad. We carefully tipped the jointer up enough to drive four more screws up through the slots underneath and into the plywood again, providing a satisfying level of tension on the belt. Then I hoisted the heavy cast iron belt shield into place, determined that it did not rub against the pulley, and bolted it into place. The thing was largely done.