Hi all,
I wonder if I could get some advice on saving a 70-year-old drill. It's a Stanley H12-B, 120v, single phase, single speed, geared, non-reverse universal three amp motor. One field burned out and I rewound it with the same ga. wire and number of turns but it now turns backwards. Diagrams I've found all show series wound, either one line going to one field then to one brush or a line going to both fields in series and then to both brushes in series. They all say it can be reversed by simply swapping wires to the brushes. I've tried both configurations and every combination there is and it always turns the same way. Any suggestions? Thank you.

Rick A

 

If the drill motor runs backwards then somehow the magnetic flux relationship between rotor and stator has become reversed. It may be that only one of the two fields is reversed and the other one is not having much effect. You do not mention if the torque is the same or not. So it may be that ONE stator winding is reversed and the other is not active.

 

Are you sure you wound the coil in the same direction? See: https://web.ua.es/docivis/magnet/righthand_rule.html

Can you reverse the leads to/from the coil you rewound?

 

What you could do is to power the fields in the same series configuration as you have them now and pass a small DC current through them, then using, say, a compass, see if the fields are of opposite polarities and then see if both change when you swap the DC power polarity.
Max.

 

Sounds like the Field windings are out of phase with each other, try Max's suggested approach test for polarity with a compass.

 

Thank you for your suggestions. Gives me something to try. I'd thought about reversing the field coil I rewound; sounds like that might be the problem. I'll let you know in a day or two.

Rick A

 

Thank you again, everyone. Per your suggestions I swapped my homemade field winding face-to-back and the drill works fine now. I don't know enough about the internals of motors to understand why, just glad there are guys like you around to turn to.
It's mounted in my DIY mag drill.

Rick A

 

You most likely had the same polarity on each field, they have to be opposing i.e. a N and a S, at any given time.
Max.