Dremel - Bits Wobble?

[Ruler2112]

I made a jig for my lathe that holds the dremel in a set location, allowing me to rotate the lathe by hand & pierce circumferential grooves through the bowl mounted in the lathe. Had problems with the first bowl I tried using it on (resulting in the bowl exploding in my face - glad I had on a shield! ) because of shortcomings in the jig, but those have been fixed & the jig now works great. In fact, I'd likely have a nice pierced bowl right now except for one small problem - the rotary saw wobbles when I turn the dremel on! It's such that I cannot turn it all the way up without excessive noise from the vibration. Running slow makes it obvious that it's going to cut a very wide kerf, if it doesn't tear the bowl apart that is... walls are right around 1/16" and so don't have a ton of structural integrity.

I've never noticed this before, probably because I've never mounted it before and my hands/arms absorb any vibration present. (I confirmed this by turning it all the way up when holding it instead of in the jig without changing anything else; no noise.) I have 2 more off-brand dremel-like tools, both of which were still in the box and unused until tonight, and both have exhibit the same behavior. I've tried several different bits, even the machinist-grade carbide cutters I have, and now that I know what to look for, I can plainly see the wobble even when rotating the head by hand. It's hard to see when running under power at anything under a few dozen RPM, but it's there.

Has anyone else noticed this in their dremel tools? Any tricks on how I could eliminate it? (Hate to think that I've built & revised this jig to now turn around & chuck it in the trash... )

[Robert Adams]

The older model Dremel was not a very well designed tool. It had a seperate motor and output shaft. The output shaft had tiny bearings that were smaller than many in rc cars. They couldn't take any load before wearing. It also used a rubber tube that coupled the motor to the shaft.
The bearings wore fast and the tube would break. In fact they didn't have repair parts shortly after they changed the design. Lots of wobble in those versions.

The current ones have a one piece armature and output shaft which allows for a stronger tool and bigger bearings.

That said I have had massive amounts of slop in the older styles even when new but the current style I haven't had a problem. Mine is dead smooth with any bit I put in it.

Any time I have seen wobble it's due to using the chuck Instead of the collet or just a bad collet. I don't use mine very much bit it does come in handy .

[bgosh]

I have found that what Robert said is true and sometimes it is the bit is either out of round or has worn somewhat on one side to make it out of balance.I have brand new ones that are like this and the only way to stop it is to back off the rpm of the Dremel.Also check on the recommended rpm of the bit,I don't remember what the rpm of the Dremel is but some of these machines are as fast as 40000 rpm. You can check that bit if it is out of round by looking at the wear of the bit or the collection of dust on it.It should be continuous and not just on one side.It also could be a bent shaft,I have that happen also if I stick it too far out of the collet or chuck, causing it to wobble.

[bgosh]

I have found that what Robert said is true and sometimes it is the bit is either out of round or has worn somewhat on one side to make it out of balance.I have brand new ones that are like this and the only way to stop it is to back off the rpm of the Dremel.Also check on the recommended rpm of the bit,I don't remember what the rpm of the Dremel is but some of these machines are as fast as 40000 rpm. You can check that bit if it is out of round by looking at the wear of the bit or the collection of dust on it.It should be continuous and not just on one side.

[bgosh]

Sorry about the double post.

[EricU]

I think they got rid of the rubber tube models 20 years ago. Lots of luthiers use dremels, and Dremel actually listened to them when they complained about the design. Having said that, it's pretty hard to make a cheap, high speed design.

Last time I looked, they would replace a tool for a reasonable price

[Robert Adams]

Yeah I looked at sending in my old one and by the time you ship it then pay the repair price you are at the cost of just buying one at the store.

Their balancing has gotten much better over the years too. Those things spin pretty fast. I usually use mine when I break a bolt in something...

[oakey]

I use my dremel tool some for inlay work with a plunge base and a little free hand use
for sure dremel tools are made at a price point rather than a precision tool
try some different collets that is one thing I have found that helps
and the collets do not last long so buy extras
they damage easily once damaged they allow the bit to wobble all over the place