Fabricating a forward & reverse switch for a Black & Decker drill

One day I was using my Black & Decker drill to unscrew a hinge from a wooden door which I was thinking of reusing. Nowadays wooden doors are becoming pretty expensive depending on the type of wood and size. So, I was going to keep the door as it would definitely be useful one day.

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Coming back to the drill, I needed to screw back some of the screws into the door minus the hinge for storage. When I tried to reverse the drills direction of rotation for screwing in instead of unscrewing, the switch failed. Well, after almost seven years of faithful service something was finally breaking down.

Later when I had the time I opened up the drill and scrutinised the circuit. The toggle switch had worn out and would need to be replaced. Unfortunately my drill was such an old model that the part was no longer available. Since the motor itself was still in good operating condition I decided to fabricate an external toggle switch.

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Following the internal circuitry of the drill it was clear that the drill reversed it’s rotation when the live and neutral (single phase) were reversed. It was then a simple matter of buying a double pole, double throw toggle switch, housing it in a small plastic box and appropriately connecting it to four wires joined to the original contact points of the faulty toggle switch. Cross connecting the top two poles of the switch with the bottom two poles and with the center being common ensured that throwing the switch from end to end would effectively reverse the circuit.