The Craftmans Shop > New from Old
Bridgeport J Head Pancake Motor
awemawson:
I managed to do a bit more investigation with the motor today. Of course the symptoms changed half way through :bang:
Six wires on this "Dahlander' pole switching motor that can be switch configured as two pole or four pole with a complicated switch to do the job. I made up a table matrix of the six wires and wrote down inter-wire resistance values and it soon became obvious that 'C3' was open circuit - it hadn't been.
Then I removed the rotor to closely examine the exposed windings, and found damage to three wires which my ohm meter tells me are connected to C3 - sadly I cannot remove the stator winding to see the other side - it seems to have been pressed into the 'blind' housing and will require something making up to jack it out, and it is on this far side where the wires go to the outside world.
My guess is that something metallic has been ingested shorting those wires which has weakened the outer connection which has now broken :(
I have been able to test the complicated switch (5 positions with 12 poles) against the Bridgeport manual, and it checks out (except it looks as though forward and reverse are exchanged)
Conclusion: I still need a new motor !
Sea.dog:
If that's the only damage evident I'd repair each of the three wires and meter it. What have you to lose?
awemawson:
Graham, the three wires are not broken they are still continuous just scalped but C3 is not connected to anything other than these wires - no external connection!
I found a reference on the web to the stator being a light press fit but retained by two grub screws. Seems mine only has one grub screw. (I even chopped off the rivets for the label in case #2 was underneath - but no!)
So by warming the aluminium casing, supporting the windings / stator stampings with my fingers, and using a plastic mallet tapping the casting I have moved the stator 19 mm in an outwards direction. I had to stop as by this time the stampings had warmed up too much for a temperature differential, but by the morning they should have cooled enough to start again.
Sea.dog:
I couldn't make out whether or not one of them was broken, but I suppose that would be the first thing that you would check. Good to see that you're making some progress Andrew :thumbup:
awemawson:
I had a brief further go this morning Graham but couldn't put much enthusiasm into it.
I came down this morning to find our older dog Cleo had died over night - she was ten. So first job was to dig a large hole in the orchard and bury the poor thing. Frankly bashing on the motor housing was just to release a bit of frustration and not very productive.
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