After replace motor carbon brushes, it sparks badly.
This may caused by many reasons.
1, commutor uneven surface
worn commutator where the insulating separators are proud , this can cause arcing, also cause carbon brushes worn out rapidly. we need to machin commutator with lathe.
2, dirt (greasy carbon dust) on the commutator
Please clean all dust with compress air, we also need to clean out the mica insulation slot. After that, please also polish the commutator with fine sand paper.
3, armature winding short
this may cause excessive current, severe sparking, reduced speed and power, and overheating. The thermal protector, fuse, or circuit breaker may trip. measure resistance of armature winding, if there are any short, we need to replace the armature.
4, rotor winding short
measure resistance of rotor winding , if so, we need to replace the rotor.
5, dry or worn bearing
replace it with new bearing
6, springs do not move freely
adjust spring and brushes holder
7, brushes holder is lose/not stable
tight it up to the base, make sure carbon bushes are in right position.
8, brushes holder is too far away from the commutator
adjust the distance of holder, it should be between 1-3mm.
9, poor connection between carbon brushes and commutator
polish the surface of commutator and carbon brushes, remove all oxide and dust.