The HobbyMat BFE 65 again

Thanks to you Joe, John, and Martin. As with others who have contributed to this thread, I really appreciate your comments both electrical and mechanical.

I must also apologise if I keep repeating myself. My own knowledge of electrics and electronics is relatively flimsy, and although my father was an electrician, I still rely heavily upon others like yourselves for technical support and confirmation. Conversely, my friend has a respectable background in these fields, and used various pieces of test equipment to determine the motor issues.

With mains connected directly, ie. bypassing the START/STOP solenoid etc. the motor runs up to speed. However, there is a distinct hum which concerned my friend. As I’ve mentioned before, the centrifugal switch can be heard operating, but according to the current-meter reading, there is current flowing through the capacitor.

To close a few loose ends, when I tried the solenoid START/STOP operation with the motor disconnected, it failed to latch. But it did produce the pulsating mains hum I mentioned before. So there’s a `Non-latching’ fault which needs fixing. I suspect that if the centrifugal switch has failed to open and therefore failing to disconnect the capacitor during the running mode, the protection circuit may have suffered.

We didn’t investigate the centrifugal switch, but this afternoon, I removed the cowl, the nylon cooling fan, and the die-cast cover over the centrifugal switch. A long brass screw passes through a bush and the motor shaft to keep the rotating parts of the switch in place. However, without a puller tool, I wasn’t prepared to try removing the bush and the rotating parts. The bush was firmly stuck to the shaft!

It wasn’t possible to see the switch contacts or the wiring Martin, although I could move the sliding part of the switch, ie. the part which is usually toggled from one position to the other and back again. The mechanical parts all appear to work freely against their respective springs.

Having reached this point, I have decided to leave things alone until I’ve spoken with the owner of the HobbyMat lathe/mill. He may choose to take this on board himself, and I need to get on with finishing the clock.

By the way, although I don’t know what the current-meter is actually called, it has large, heavily insulated jaws which open to surround and close around a single wire. I presume that it determines AC amperage by means of the induced magnetic field.

Joe - thanks for your description of how to place the T-nuts. I did it once before, but it was all lying on the bench, and the bolts were at 12 and 6 o-clock. The first one went in a treat, but I had to jiggle around for the second one. A good blob of grease will do fine, but would you believe that my tin went out the door when I got rid of my workshop? Currently, that section of the mill is now on the vertical column, and the bolts are at 3 and 9 o-clock. I expect that I’ll have to fish a little.

Given more time, I would be inclined to machine a ring of wood or similar material to fit loosely in the T-slot. This would be cut into two pieces removing the extra material where the T-nuts normally sit. Given more time, a ring made of steel could be used, suitable threaded to completely replace the T-nuts. Of course this would require unscrewing more screws to access the back of the T-slot.

Thanks again.

Sam