Thread: re- replaced brushes now sparking

Look in yhe Triton Forum above and see where to get parts in the UK.

Hi Peter, sometimes new brushes will spark a lot untill they bed in. Old brushes have a curve worn into them giveing them good surface contact, the new ones still have a flat surface (with less surface contact) untill you have used the tool for a while at which point it should settle down.

Dear Peter,

Claw has got it spot-on. I will add that if the Brushes you modified were already "used", they will have developed a curvature on their ends that might have a slightly different radius to what you need, because the Slip-Rings on the Armatures of different motors will all have slightly different diameters. The sparks that result if this is the case will eventually die down after a bit of use.

Again in the case of their already having been used, you could also try twisting them around by 180deg in their little housings, because the shape of the curve worn into their ends can become biased after use in the direction of the (old) Armature's rotation due to slight tolerances between the brushes and their housings, and you might have inadvertantly put them in with the resulting wear-bias facing in the wrong direction...

They also need to have a fairly good front-to-back (as opposed to left-to-right) fit in their little housings, otherwise they will drag over too far upon contact with the Slip-Ring, which can possibly lead to overheating and excessive sparking.

Best Wishes,
Batpig.

I would suggest that you dress the brushes to fit the commutator.

The usual approach is to take a thin strip of emery paper that is a little wider than the brushes and sit it between the brush and the commutator with the paper-side down on the commutator. You then slide the energy back and forth to hone the face of the brush to the shape of the commutator (Okay, okay, the radius will be a little bigger on the brush due to the thickness of the emery).

The other thing to look at is the commutator. It too may need dressing if it is worn and grooved. A flat file works well on the commutator (spin it in a lath or drill and bring the file to bear on the commutator - but don't slip and hit the wires).

The segments of the commutator should have a slight bevel on each edge - a quick (and careful) pass with a triangular file between each segment should do the trick.

After all the above, clean the commutator and brushes as you won't want metal filings in your motor.

I agree with all above and add what you know already, probably, that even at the best of times, brushes will spark a little.