I use an old dynamite dial charger, you set the time & the amp rate with a dial, works good, i can vary the rpm by the anount of amps with the dial, the six cell battery will work but you will be turning a lot of rpm, try using just four cells.
I also use a 4cell pack for my lathe. What I did was turn a 6 cell pact into 1 4 cell and 1 2 cell. I use the 4 cell for the lathe and the 2 cell for breaking in the motor.
The lathe spins a little fast when the pack is full. Just remember to always use cutting fluid on the comm and you will be able to get perfect cuts easily. Alot of shops sell an rc cutting fluid or you can get some at your local hardware store.
You can use the "Good Olde" AT PC power supply, the standard power supply in almost all computers made in the last century. I have one and I've accidentally jumpered the output wires many times and it still lives.
You ususally get 5 volts between the black and the red wires and 12 volts between the yellow and black wires. The lathe would turn a bit too fast with the 5 volts, nothing you can't live with, but if you connect discharging bulb in series with the lathe motor you get just about perfect speed and the bulb acts as a load indicator, it glows brighter the more load you put on the lathe. The 12 volts are of course fine for your charger.