I have a Sieg X2 Mini Mill from Harbor Freight. I modified it to use as a tool and cutter sharpener until I complete making a Bonelle T & C Grinder.
I have always been disappointed with the motor and the motor control. It has stopped working several times. I have broken several plastic gears and replaced them with metal.
Recently I decided to convert to a belt drive. I did online research. I made the parts. I used the kit by Sterling Steele as a guide, I used a two step pulley. I used the belt from Little Machine Shop. What I accomplished was to burn up the motor and controller. The controller just stopped. As soon as the belt was tightened the motor overheated, started to smoke and burnt several parts. Any more power after this point would burn the brushes, springs or spring connectors. I used a controller I had from Surplus Center to keep testing. I was able to repair the motor with parts from Little Machine Shop. I also used high speed sealed bearings in the motor. It ran much better with no load but any radial load would start it smoking. The controller can be repaired by Gerling Laboratories at Repaircontrol.com.
While I waited for parts I took the spindle apart to remove the two step gears. It was pressed together so tightly I could not remove it with a 3 ton press. I replaced the bearings with sealed bearings from VXB Bearings. I polished the spindle until the bearings would slide. It turns much better but I may polish it again as it still gets hot. I did a break in period for the new bearings. I experimented with pulley diameters. I wanted to get about 4K rpms top speed as I use diamond wheels for sharpening. I used a 1/2 hp Reliance motor, 1,700 rpm. This may be too slow for a future CNC conversion.
I finally replaced the motor and the controller. I can only guess that the controller stopped because of the motor load. I do not know why the motor will not work with the pressure of the belt on it. I did have trouble adjusting it when I changed the broken gears. If the gears were tight the motor would pop the circuit protection.
It runs smoother with much less noise. The finish from the grinding wheels is improved.
