Thread: Erbauer ER2100 sparks after changing the brushes

The commutator on the end of the armature where the brushes run needs machining off to be clean and square.

Originally Posted by riverbuilder

The commutator on the end of the armature where the brushes run needs machining off to be clean and square.

Possibly; but done professionally would cost more than the router is worth. There are a couple of things you can try first; but you need to be able to remove the cover and access the commutator and brushgear.
1. Firstly; blow out the brushgear with compressed air. You may just have a heavy build up of carbon dust from the old knacked brushes.
2. Remove the brushes and inspect the commutator segments; if they are really badly burnt and damaged then skimming is the only fix but if the damage is light then wrap a strip of 400 grit around it and rotate the shaft to clean and polish the segments. Again, blow out the residue. Inspect the gap between each segment closely; if any copper has melted or smeared into the gap it must be removed by scraping. You can make a scraper from an old Stanley knife blade; just grind off the edge to make it blunt and square ended.
3. Bed the brushes; they were probably supplied with square cut ends. These need to be rounded to mate with the commutator. Do this by again wrapping a long strip of abrasive paper (paper not cloth backed) around the commutator but this time with the abrasive on the outside; 240 grit would be fine. Put the brushes in place and pull the paper ends back and forth so that the paper is gently abrading the ends of the brushes and contouring them; you might need to do one brush at a time.

Thanks everybody, I will try and see if it works.

Alberto