Death of my Dremel

[Chems]

Fired up my dremel this evening as I had hoped to use it for some routing tomorrow wanted to see if any bits I had worked. On starting it up its making a crunching noise. Took it apart and gave it a good blow out and had a look around. No obvious signs of a problem. It spins perfectly when I twist it with my hand but when I start it up its making horrible noises. I'm at a loss to see what wrong with it anyone have any ideas?

 

[9fingers]

Are you getting sparks from the brush gear?

if so either brushes too short/springs weak/brushes jamming

or bad new armature damage - replacement needed - possible priced at more than a whole new tool.

Good Luck

Bob

 

[Eric The Viking]

Fired up my dremel this evening as I had hoped to use it for some routing tomorrow wanted to see if any bits I had worked. On starting it up its making a crunching noise. Took it apart and gave it a good blow out and had a look around. No obvious signs of a problem. It spins perfectly when I twist it with my hand but when I start it up its making horrible noises. I'm at a loss to see what wrong with it anyone have any ideas?

12V or mains version?

It could be the brushes have given up. If it's been unused for a while, that might be it. You could gently take them out and inspect (tip: put a spot on one face of the graphite block with Tippex to get it back in the correct way round, and, if you can, do one at a time, for the same reason). You can clean the commutator with Dura-glit wadding, followed by meths to clean up. I wouldn't use Brasso as it's too abrasive and messy. If they've been sticking that might fx it.

I had a B+D equivalent burst into flames (exciting!). I think it was the brushes wot started it. I've now got a small mains Proxxon, which is pretty good.

If it's the motor speed controller, that may be a bit harder to fix in a hurry.

 

[Chems]

The brushs spark a lot, as I'm running it with half the case off so I can see clearly. There is a fair amount of wear and this was my first ever tool so had it for a while. Its a mains jobby.

I didn't realize the brushes could cause such problems. Would grinding them back to a level surface help? Its getting very hot after about 5 seconds.

 

[9fingers]

If it gets that hot then it is most likely the armature knackered although it is just possible that if it is running slowly due to brush problems, the cooling air from the fan is in sufficient.

My money is on you needing to replace it

Bob

 

[George_N]

I don't have any help to offer on the dead Dremmel front I'm afraid, but I would like to ask you about routing with the Dremmel. I was looking at the Dremmel section in B&Q the other day and I saw some of the tiny router bits. I wondered at the time what sort of projects they might be used for and what sort of job they do? Sorry, don't mean to hijack the thread.

 

[Chems]

Well I was planning on doing inlay, they are only good for tiny things as the bits are so weak.

I can't see anything wrong with the armature but that would make sense as the brushes look like they are doing the work.

I won't buy another dremel, pendant motor and flexible shaft would be better.

 

[Eric The Viking]

The brushs spark a lot, as I'm running it with half the case off so I can see clearly. There is a fair amount of wear and this was my first ever tool so had it for a while. Its a mains jobby.

I didn't realize the brushes could cause such problems. Would grinding them back to a level surface help? Its getting very hot after about 5 seconds.

Suggestions:

1. clean the commutator (the bit the brushes touch), as discussed. When it's clean, check for pitting at the edges of the copper pads, and using a sharpened matchstick, clean the gaps between the pads (gently!), so that there's no carbon bridging the gaps. If badly pitted, you'll have to discard the tool.

2. stretch the springs slightly, so that the brushes make slightly better contact.

3. replace the suppression capacitor (usually near the switch) - this may reduce the arcing a bit.

The brushes should wear to take the shape of the commutator. This is correct -- don't flatten them off! If the brushes look as though bits have broken off, or appear rumbly at the edges/corners, they are failing.

Similarly, if they're very worn down they may not contact square-on to the commutator, leading to sparking. You can correct this to an extent by stretching the springs, but if they're very worn down, they may not run straight in the housing, and will tend to scuff rather than slide smoothly. As a guide, when they're roughly square (or the same length as the diameter if the round type), they need replacing.

If you can't get replacements, you may have to junk the tool.