Dremel Tool Salvage?

4

4WDlifeform

NAXJA Forum User
Location
Beaver Falls, PA
I got a Dremel 400 XPR for Christmas, maybe 3 years back. I love this tool. It always seems to end up contributing to just about every project I work on, in some way.

Sadly to say, I was cutting some hard-to-reach sheet metal under the fender, and she started spittin and sputterin really bad. The past few times I had used it, it started getting hot really fast, and giving off an odd smell (yes, im sure it was coming from the dremel :laugh3:). But, this time, she completely crashed. It will still turn on, and run, but its not pretty.

You are now thinking... BRUSHES! But... I don't think so. I pulled them out, and there is plenty of carbon left. According to the booklet, once it gets to about 3/8" of carbon, time to replace. I have near 3/4" remaining. Im asking if any of you are familiar with this (or similar) devices, what I should go about doing/trying? I suppose I will try new brushes, just for kicks. Just curious of some feedback though before I drop money on it.

Thanks a ton!
 
I had a dremel that lasted 2 months, normally I have good things to say about quality pieces... but I went with a cheapo Mastercraft (Canadian name) one and have had good luck.

if its spittin and sputtering, does that include wobbling of any kind? any chance the bearings overheated and have bugared the motor, or the bearings themselves are bugared??

I tried contacting dremel and since it was a gift they would do nothing for me (no receipt)... but you could try that route and see if they will help out anyway.
 
I had something similar happen to my old Dremel (probably 15 years old or so,) and it turned out the bearings on the rotor were shot.

Do recall that the rotor is good for up to 30Krpm, and the bearings are sealed units.

Good news - you should be able to order a new rotor assembly (including bearings) from Dremel for rather less than the cost of a replacement tool - email or call them and see. Mine only cost something like $20 shipped - but mine is an older tool (as I mentioned.)

Throw the old rotor in the "electric coils and cores" bin for later scrap metal sale. It's what I do with small transformers and electric motors that I salvage (they take them as "dirty electrical copper." Where possible, I'll strip wire or unwind coils & cores - that's "electrical copper," and pays about three times as much. Wire that's too fine to strip goes in the "Comm Wire" bin.)
 
since you are comfortable removing and replacing brushes (a lot of people aren't) i would take the whole thing apart, clean the armature and winding with a decent electrical cleaner (like CRC's "Lectra-Motive" Electrical motor cleaner) and lightly sand both the face of the brushes and the commutator (the area of the motor the brushes directly contact). If that doesn't clear up the problem I would take a look at any circuits and wiring inside the unit, looking for scorched or melted parts.
 
I bought a 2xx last year to replace a 1xx that had lasted 15+ years, and the new one only lasted a couple of months tops. It started making a grinding noise and running really hot. I took it apart and the plastic bearing/bushing that holds the output shaft fell out in pieces.
 
Thanks guys. Actually, now that I'm thinking more about it, I would not at all be surprised if its a bearing failure. I should have some time tomorrow to strip it down, and see what I can find.
 
Once you have the rotor out, turn the bearings with your fingers. A failure will be obvious (and will actually be more likely on the rear bearing than the front, due to leverage in use. That's why the manuals and common wisdom say that you use about as much force on your Dremel as you do when writing. Let the speed of the tool do the work - the bearings aren't that heavy!)
 
Alright. Finally got around to doing this... Got bad news...

Here's the rotor assembly, right out of the dremel:
DSC_0607.jpg


Bearings were OK. The "stator" (the copper colored part that the brushes ride on??) (im a mechanical engineer... not electrical haha) so if my vocab is off, im sorry. But... i thought it looked dirty:

DSC_0599.jpg


...so I found some 800 grit sandpaper and lightly cleaned it up.

Also noticed some metal filings in the magnet cage thing... cleaned them out as much as possible. Put it all back together. Ran it. and, no different. Double checked the brush springs, took it back apart, almost immediately. Stator looked like this. Before I ran it, it was almost completely bare copper (no black, basically):

DSC_0605.jpg


the rotor (where the coil windings are) was really hot!! only after... 5 seconds or so of running. Electrical short maybe?? Put back together. ran it again, and i think its done for good now. Spit real bad, i tried turing up the speed, and it left one last big pop, stopped rotating, and some black smoke rose from the vent.... :explosion I think I lost.

What are you guy's feel on this?? time for a new dremel? Still hope??
 
yeah... that looks like you probably should have used finer sandpaper, and done it by putting the end of the shaft closest to the commutator (the striped copper bit) into a drill press and spinning it up while holding the sandpaper against it. This would result in a good cleaning without making low/high spots like doing it by hand would. It may have been too rough, it looks like it caught on one of the brushes and arced + burned out a coil by remaining stationary with the full current flowing through it too long. When that happens, the only thing limiting the current is the resistance of the wire, the energy is no longer being converted to rotational movement so the coil goes :flame::explosion

Looks like time for a new one to me...
 
I dont know what a new dremel runs, but I think its around like $160. At work, we use Dumore grinders; they are MUCH more heavy duty than my 400 series Dremel and have last for longer than I can remember and we use them most days (sometimes for extended periods of time in a fixture on the lathe to grind carbide). They are more heavy duty than needed for the most part, but they purr like a kitten when you turn them on (much quieter than my dremel).

It's a heftier price tag at around $310 new, but worth every penny honestly. I will be asking for one for my upcoming birthday (We still make a big to-do about birthdays so I might as well utilize it; I'm 23 years old though).

It's an option for you since you're looking for a new dremel, but there are a few things to note:

You lose variable speed, but this thing run 2.2x faster than a 400 series dremel (22k rpm)

You gain strength and rigidity in your collet setup (you use two 7/16'' wrenches instead of that button that wears out and the tiny wrench provided. )

You can use 1/4 inch bits and 1/8 with the brass collet adapter.

The Dumore doesnt fit in your hand quite like a dremel and it doesnt have a flex cord attachment, but I still prefer it over my Dremel anyday.

It takes much longer for the Dumore to overheat/ get hot (even at 10+ years of age) vs. my rarely used Dremel which is about 2 years old.


http://www.mcmaster.com/#dumore-die-grinders/=6f8fts

That is where you can order it that I have found to be the cheapest, but if you find somewhere cheaper, then please let me know. (Item K toward the bottom, Price is around $310).

Hope this information benefits someone.
 
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