This instructable may seem a little counter-intuitive, why would you take a cordless drill and put a cord on it?

Well I bought this ROK 14.4V cordless drill to use as a cheap screw gun about a year ago (I use my good 18V cordless to drill the holes). The drill came with 2 batteries and I have obviously favored one as it now only holds a charge for about 10 mins. The drill cost about 70 euro and I do like using it as its well balanced, however, I could not track down a replacement and a local tool center quoted 110 euro to rebuild so it would be cheaper to buy a new drill.

I have seen some tutorials on fully converting to corded but I still have one good battery and I also have a good corded drill so I came up with this. I use a mains voltage to DC converter and adapt the failed battery housing to supply the drill from the mains and I can still swap to the battery and go cordless when needed.

WARNING!!!!

THIS INSTRUCTABLE DEALS WITH MAINS AC POWER, THERE IS A RISK OF SHOCK RESULTING IN INJURY OR DEATH. PLEASE ONLY FOLLOW THESE INSTRUCTIONS IF YOU ARE COMPETITENT TO DO SO. ALSO THIS INSTRUCTABLE DEALS WITH MODIFICATION OF A POWER TOOL, THIS MAY RESULT IN DAMAGE TO THE TOOL AND WILL VOID ANY WARRANTY YOU MAY HAVE.

Step 1: What I Used

For this instructable I used:

Cordless drill with dead battery
230AC -> 24DC power supply (10A)
2 pole MCB (6A)
gG fuse holder and fuse (6A)
Fibox enclosure
DIN rail
16mm cable glands x3
4m 3 core 1.5mm sq cable
Assorted ferrals and barrel crimps

Step 2: Power Box

As I said earlier, the drill is 14.4V. After measurement, I found that the drill draws 6A at full speed and no load.

This results in 14.4V x 6A = 86.4W

I had a spare 24V 10A power supply, using the adjustment I could dial this down to 22V, not really caring about the drill that much and knowing that they are usually fairly tolerant I tried it and there was no excessive heat or burning of the motor. I did not test the drill running continuously, this is used as a screw gun and is used in short bursts, there is no hammer action so I do not use with masonry. If you plan on running continuously then you need to better match the power supply to the drill.

The resultant current requirement is 86.4W/22V = 3.92A

I started by fitting 2 cable glands on the side of the box.

I cut and mounted some DIN rail inside and mounted the 6A MCB, power supply, and the fuse holder.

I wired the 230V AC supply through the MCB for mains protection and to provide isolation if needed.

From the 24V output, I wired the + though the fuse. In an ideal world, I would have used red/black 2 core for the DC, but all I had to hand was regular 3 core.