Treadmill permanent magnet DC motors are popular amongst home machinists because they are readily available from scrapyards and similar, as well as being easy for variable speed.
This post shows how I modify such motors to make them more suitable for the task of driving machinery such as small lathes, drills, mills and grinders. Some unusual machining techniques are demonstrated. The main focus is on grinders because they have addition problems due to magnetic grinding dust.
The video shows several areas of attention which needed improvement such as bearing fit, bearing alignment, general rigidity and for grinding use the need for sealing. Some unusual machining techniques are demonstrated.
The objects in question. (click images for full size.)
Before and after main bearing carrier (above).
Truing the casing.
Truing the flat belt pulley on the armature.
All the bits.