DDR Smalcalda Drill: Sparking Brushes on Commutator - Causes, New 6x6mm Brushes, & Solutions

Hello,
I have a drill made by DDR Smalcalda and when I got it, it turned out that there are brushes to replace. Not because of wear, but simply one that burst and the cable fell off. I bought brushes 6x6 [mm] and after assembly they caught the attention of sparking on the brushes. I am not able to say for sure if such sparking is a cause for concern.

I noticed some facts that may affect this behavior:

1. The new brushes are profiled at the ends to a round commutator (which I think is a big plus) but the part that connects to the commutator is not smooth, but it still has small fringes, can it reach? Because of this, it does not adhere exactly to the commutator. If this can cause such a problem, I can always try to grind them on but I do not know if I can keep the shape adapted to the round commutator.

2. The new brushes are as if "less" carbon, that is, the old ones were black, as if all made of carbon, and the new ones probably have some larger admixture of copper dust you can see it by color.

3. The capacitor on the power supply is quite bad and quite strange at all. The inscriptions on it, unfortunately, not very legible I assume that it is 0.1uF. In addition, the capacitor has a tap on a metal part of the stator. I put a drawing of the capacitor and ask for information why there is an additional tap on the metal part of the stator? Is this a rather rare solution? Can the capacitor itself, which is parallel to the power supply, affect sparking, or maybe this tap on the stator dirty? Thank you for your help.

Pictures of the drill and sparks during operation:


The capacitor seems to me that it has this structure:

Pioro33 wrote:

But the part that connects to the commutator is not smooth, but it still has small fringes.

These fringes are not reaching, but this is how you see the commutator contacts that switch the windings in the rotor during motor operation.

Hello - have you used replacements or the first better 6x6mm?

We didn't understand each other about the stripes
The commutator plates are of course one thing and everything is fine here.
Just the part of the brush in contact with the commutator is not smooth, I found a picture showing what I mean.


Brushes were bought in a power tool store, for the drill that I need. Generally, they are not dedicated to my drill because it is historical. Perhaps it is better to choose the material from which they are made. Any hints what to buy and where?

Hello - the contact surface of the brush with the commutator should be smooth (depositionable)
to the commutator surface).
Please try other brushes - for example;
http://narzedzia-katowice.pl/produkt/6683/Szczotka-6x6x16-na-PRCB-500W,350W.html

Sparking of brushes, especially new ones, indicates that brushes reach the commutator.

jar190 wrote:

Sparking of brushes, especially new ones, indicates that brushes reach the commutator.

First of all, this is a pathology and indicates the wear of the commutator. The plots should be cleaned and in the absence of access to the lathe, use fairly thick sandpaper. I run the device through the autotransformer and apply a piece of paper from the side. It should not be sparking or barely noticeable.

And how do you do it on a lathe? Please enter a way.