Anyone know how to wire a drill motor?

[Travelover]

I have an old Milwaukee 3/8" drill that had the reversing switch disintegrate. The variable speed trigger still works. To avoid paying $40 for a new control switch, I'd like to replace the reversing switch function with a mini toggle switch. My question is how to rewire it? There are 4 wires in the circuit - two from the brushes and two from the field.

1) To reverse the rotation direction, do I just reverse the polarity of the field connections with the respect to the brushes?

2) Are the field coils wired in parallel to the brushes or in series?

Thanks in advance.

[franz frippl]

How is the present switch wired? How many terminals are there? Is the current switch SPST or DPDT?

I would take the switch to your local electronics shop and see if they can help you find an appropriate switch and maybe even give you some ideas on how to wire.

[Tom]

The current reversing switch has a rotating contact assembly, but because it fell apart, it is impossible for me to tell if it functioned as a SPST or DPDT. There are four terminals.

If I knew how the field should be wired, I can duplicate function with a toggle.

[franz frippl]

Can you locate a schematic online or in owner's manual?

[Don Young]

To reverse rotation, reverse the connections of the field with respect to the brushes, as you said.

The field coils are connected in series with the brushes.

A common DPDT switch will be good for a reversing switch. One without a center OFF position is best. Wires from the brushes should go to the common terminals, normally in the center. Wires from the field coils should go to one pair of the other terminals and two short wires crossed over in an X to the other pair of terminals. Double check that you never get a dead short between the brush leads or between the field coil leads in any switch position and you should be good to go. If it should make it any easier to connect you can interchange the brush wires with the field coil wires on the switch.

Don Young

[Joe]

Who in the world told you the switch was that pricey? I have a 3/8 Milwaukee that used up the reversing switch a few years ago, and IIRC the price then was about $8. Shop around, maybe some electronic surplus might have what you need. Good luck/\\.

Joe

[Tom]

Thanks to all that replied. I think Don has the answer for me. The switch prices were from internet parts suppliers.