Is this normal for a Model G

[crazykirbydude]

I finally got around to rebuilding my Electrolux Model G. The carbon brushes were mere slivers, so I replaced them with a healthy set. After testing it, I noticed more arcing than usual. The commutator has a groove worn into it, but it didn’t arc like this with the old brushes. Is this normal, or did I just damage my motor?

 

[crazykirbydude]

I forgot to mention that I can hear arcing. Otherwise the motor is healthy.

 

[rowdy141]

I can't see a great level of detail from your photo, but it is usual for new brushes to arc a fair bit, until they're run-in.

There is a processes called dressing(?) which speeds-up that settling-in period by grinding a hollow in the brushes to match the curvature of your particular commutator.

The worn groove in you commutator may have been caused by the brush-casings when the brushes wore down to slivers, depending on their design.

I would expect your new brushes to wear quickly where they're arcing now, until they match both the commutator curve and groove, then they should settle down.

You can gently sand your commutator with very-fine abrasive paper. That will remove dirt, glazing build-up, and smooth out the groove. So long as there's enough 'meat' on it so as not to go through the thin copper entirely.

 

[crazykirbydude]

These weren’t brand new brushes, they were used, but they are in great shape. They already have a curve worn into them.

 

[rowdy141]

Unless those brushes were worn on a commutator of exactly the same radius, they will still need to bed-in. Even if you swap brushes around 180 degrees when checking for wear, they have to re-seat again.

That worn groove is going to cause arcing and/or noise too, isn't it?

 

[crazykirbydude]

I ran the motor for about 30 minutes to seat the brushes, but it still arcs. Do I need to give it more time?

 

[dysonman1]

You need a carbon brush seating stone. The excessive arching will ruin the armature if you don't seat the brushes correctly. It only takes about 5 seconds, hold the seating stone so it touches the armature as it's rotating, place it right before one of the brush holders. It will make the new brush concaved to the armature and reduce the arching to 'normal'. Also, remove the brush holders and CLEAN THEM with a small brush. You want all the old carbon dust out of there so the new brushes slide freely back and forth. You can order carbon brush seating stones in a box from the internet. I work on vacuum for a living, and haven't used up all the stones I got ten years ago. Best if you can just get ONE stone from a vacuum shop.

 

[crazykirbydude]

Well, these brushes were pulled out of a Electrolux Model 30, which has a very similar motor to the Model G. The brushes were already concave. Do I still need to do the stone treatment?

 

[dysonman1]

Each commutator is different. You always need to seat the brushes to a 'new to the brushes' motor. Makes a huge difference.

 

[electrolux-dude]

It's possible that your model G has larger brushes than a model XXX, some model G have 1205 style brushes, and if you put model XXX brushes, they will arc more, because your brushes will wobble in the housings. If the vacuum motor does indeed have the larger 1205 style brushes, you'll have to replace with the 1205 style brushes then use commutator stone to seat the brushes. Usually a model G motor that has bigger brushes you'll see red windings instead of black windings.

 

[crazykirbydude]

The motor is from an early Model G, so I would imagine that it would use the smaller carbon brushes. I’ll open it up to make sure. The brushes didn’t feel wobbly when I put them in though.

 

[electrolux-dude]

One way to tell, the larger brush housings are usually red, and model 30 housings are black.

 

[crazykirbydude]

Yeah, then I definitely have a Model G with Model 30 style brushes.

 

[panasonicvac]

I'd second with dysonman1

That's the first thing I would usually do. Definitely makes a big difference. This is one box that I've been using for a year now at work. Out of hundreds of vacuums that I've repaired, I've only used this twice.