I want to share with you how you can power on a wiper motor with a PC ATX power supply.
Basically, this is what I'm using to power my small ball mill and it works perfectly for my needs.
All you need is a 12 powered car wiper motor, an ATX power supply and 2 wires, below are the steps:
1 - Identify the low speed connection of your motor (usually labelled with the number "53")
2 - Get 2 wires: 1 from any yellow (+12v) power supply wire and another from any black (ground) power supply wire
3 - Just connect the yellow to the motors low speed and the black to the motors metal body (any not painted part)
You can also see a simple video I posted on YouTube about that: https://youtu.be/dDjhqq-70g4
The next step is to power it remotely (using an Arduino board and a Bluetooth or Wi-fi shield) but I need to get the parts.
Hope to help someone that wants to use a wiper motor powered ball mill.