When you get tired of recharging the battery all the time. Its time to make an adapter. Now I have a variable power supply and I just needed a way to attach the wires to the dremel but I wanted to be able to use a battery as well. All you need to do is print this model, make some contact points and wire it to your power supply. I used some 14 gauge solid copper wire to make the contact points and some stranded wire to connect it to the power supply.