Lathe Milling Machine Speed Controller Potentiometer Guard

thingiverse

The Variable Speed Controller (Potentiometer) on some lathe and milling machines uses the same BLDC speed controller. There is a fundamental design flaw that can result in damage to the speed controller from the potentiometer shorting to the front panel which is earthed. The voltage measure between any of these terminals on the potentiometer to the metal front cover is 125VAC. The aluminum metal front cover of my milling machine is not painted on the back surface and when the potentiometer is installed, there is less than 1mm of clearance between the potentiometer and metal surface. When the milling machine is in use there is the potential for these to make contact with each other, due to vibration and cause a short circuit. The potentiometer shield/guard is designed to insulate the potentiometer terminals from coming into contact with the metal front panel surface.