rewire vsr drill for home project

[bill campbell]

Hello- I am wondering if I can take a 8.5 amp VSR (variable speed reversible) drill with I believe a universal motor and rewire it externally so I can hook up a rheostat (speed control) and a toggle/ push button switch (forward /reverse). Theoretically, the speed control and push button will replace the trigger, direction switch and speed dial. My application is for a mechanism that will have a back and forth motion that is speed controlled. So far I have visited countless motor sites including Grainger. The motors are either too costly, wrong type, or too large. I have also been met with barriers such as the Clean Air Act. I have tried going the route of using a motor similar to garage door openers but Id rather not mess around with additional capacitors and receiver boards. Is it as easy as plugging the drill into a rheostat that includes a directional switch? Im guessing not. Thank you in advance. Bill.

 

[Minder]

Using a Universal motor you need a Triac (dimmer type) controller for speed control, when reversing a universal motor you have to reverse the series field WRT the armature.
These are all integral in the drill switch, the Triac is often mounted separately on a heat sink.
M.

 

[bill campbell]

Using a Universal motor you need a Triac (dimmer type) controller for speed control, when reversing a universal motor you have to reverse the series field WRT the armature.
These are all integral in the drill switch, the Triac is often mounted separately on a heat sink.
M.

Minder- Electronic are not my strong suit..."reverse the series field WRT the armature"...I googled that and am still uncertain. Layman's terms please. Is this do-able? If so what do I need to do. If shown, I am good to do whatever. Is there a site with a diagram showing how to do this? I found nothing on Youtube. I dont want to do an autopsy on the drill. Id prefer to do basic wiring if thats all required. Also, quick question here, if I have the dimmer wired externally, why do I need a heat sink. Isnt a heat sink's purpose to dissipate heat? Thx, Bill

 

[Minder]

Yes you can use one of the external (dimmer) type power tool speed controllers, the problem is reversing the field leads.
Usually this type of external variable controllers have a heat sink included for the Triac semiconductor.
You would need to set up an external toggle switch or relay that swapped the field pair.
If I find a DWG out there I will post it.
Google motor reversing toggle switch and it should bring up lots of examples, except instead of power and motor, you will just be reversing the 2 wires going to the field, usually one has power the other goes to the armature.
So just intercept the two leads on swap them over via the switch.
M.

 

[CDRIVE]

The forward/reverse switch is most likely a DPDT (Double Pole Double Throw) switch. Also less commonly known (in the US) as a Changeover Switch. The speed control is simply a Potentiometer but the slider type instead of the round (turn knob) type your familiar with. Since you said the drill motor draws 8.5Amps I'm guessing this is a low voltage (DC) battery operated unit. If so, the Pot is most likely controlling a Pulse Width Modulation (PWM) circuit. Understanding of which is unimportant to accomplish your task.

The connections to the switch and the pot can be severed and replaced with an extension cable with a DPDT toggle switch and Pot connected to the end of the cable. The problem with this arrangement is the 8.5A your motor draws. This necessitates heavy gauge cable for the FWD/REV switch circuit because it's in the motor's power supply circuit. The longer the cable run the heavier the cable gauge will have to be for the forward / reverse switch. The speed Pot isn't in the motors path so it can use lighter control gauge wire.

Chris