Dremel sputters after brush/ switch replacement

9 years 3 days ago #1325 by roekone@hotmail.com
Dremel sputters after brush/ switch replacement was created by roekone@hotmail.com
Hey guys. I have a Dremel tool (MultiPro 395) and the multi speed switch wore out. It felt smooth when switching to different speeds rather than having defined notches. It would also sometimes start, sometimes not. I replaced the switch with a new one. Upon startup, nothing happens unless switched to the fastest speed. It does not continually spin, only sputters. I bought new brushes and have the same result. I realize a new Dremel is the easiest fix but this one was a gift from a relative who passed away so I want to fix it if possible. Thanks for any advice. Video posted below.

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9 years 2 days ago #1327 by MTR-Admin
Replied by MTR-Admin on topic Dremel sputters after brush/ switch replacement
Thanks for the post!

Not sure exactly as I'm not with the tool, but it sounds as if the brushes are not making contact with the commutator portion of the armature.

It sounds intermittent, as if there isn't a constant feed of electricity to the armature.

It could also be a bad armature with bad sections on the commutator itself. You can take it apart and see if the armature commutator has missing sections or if they're damaged, if the brushes are worn or not touching the commutator.

- MTR
The following user(s) said Thank You: roekone@hotmail.com

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9 years 2 days ago #1328 by roekone@hotmail.com
Replied by roekone@hotmail.com on topic Dremel sputters after brush/ switch replacement
thanks for the reply. The commutator isnt missing any sections but was pretty tarnished. Probably the wrong term for it. So I sanded it shiny again. I wonder if that could have damaged something? The brushes are new and appear to be touching it.

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9 years 2 days ago #1329 by MTR-Admin
Replied by MTR-Admin on topic Dremel sputters after brush/ switch replacement
If the commutator is varnished at all, it could possibly be a cause for loss of continuity, so it can cause the problem you're experiencing.

See if polishing it up did the trick and if not, well we'll dig a little deeper!

- MTR

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9 years 2 days ago #1330 by roekone@hotmail.com
Replied by roekone@hotmail.com on topic Dremel sputters after brush/ switch replacement
Well I can tell you that I have already sanded it. The video shows it's behavior after sanding the commutator. So its currently perfectly shiny and still stuttering. Thanks again! I'd be happy to open it up and take some photos of it tonight if that helps

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8 years 11 months ago #1339 by roekone@hotmail.com
Replied by roekone@hotmail.com on topic Dremel sputters after brush/ switch replacement
Any other thoughts or things to try?

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