Dremel tool question?

I cannot help you directly. However, Dremel does have a help line. 1-800-437-3635 7AM -6PM M-F Central Time.

Good luck. I hope you get your problem solved.

Chris

LVHR

A few items of thought:   Are you holding the unit so that the motor vents are covered and hence little or no air circulation is passing through the motor? 

         Also, some of these units use  BUSHINGS  and not  BEARINGS  on the armature shaft and would need to have periodic lubrication to reduce friction  that would produce heat. 

        Also any dust from grinding can be drawn into the motor area by the vent fan that is on the armature and collect along the components holding in any heat that is    generated.  Check these out to see if it helps.  Dennis M.

As Dennis mentioned, most of these have bushings.  At Sears(and other stores that carry Dremel) you can buy replacement brushes.  It will be with the Dremel bits/accessories.  This is very easy to replace and may solve your problem.

I have had mine for almost 20 years and haven't lubricated it.  However, I clean it often with compressed air and changed the motor brush once.

What are you using the tool for? Anything different than in the past? I noticed that mine tends to heat up very quickly when I am using it to cut track. The cutoff wheel slows down a lot under the stress of cutting metal, and the motor heats up quite a bit. The larger the diameter of the bit being used, and the greater the pressure applied, the more stress on the motor and so more heating. When used with an ordinary grinding wheel or polishing tool, mine hardly heats up at all - it's the large diameter cutoff wheel that makes  it get hot. 

Thanks guys.

I use small burrs and the small Dremel cut off wheels.

How do I lubricate brushes?

Bob

DO NOT LUBRICATE THE BRUSHES!

I have yet to run across an electric motor where it is necessary or desireable to lubricate them. They are composed of a material that is self lubricating.

I think that Keith may have given a bit of confusion in that he agreed with me about  BUSHINGS  needing lubrication, but he also mentioned that  BRUSHES could be replaced easily (perhaps feeling that they may be contributing to the problem). BUSHINGS - BRUSHES; close but no cigar!

As Burfle says, you do not lubricate  BRUSHES  But you need to lubricate BUSHINGS. I'm sorry for the closeness of the words.  Dennis M.

I guess I didn't word it correctly.  I meant to agree with Dennis that a little lube on the BUSHING may help...I just haven't done that yet.

When I brought up BRUSHES, that is just another thing to look at.  Many times when a Dremel suddenly starts acting erratic, running rough or noisy, changing the Brushes solves the issue.  It's possible a good cleaning and brush replacement might do the trick.

I have a Dremel I've had for almost 30 years.  I've replaced the brushes once, and I've cleaned the commutator a couple of times with Scotchbrite while rotating it in a drill.  It will overheat if the brushes get worn down, so that's the first thing to check.

Does the shaft turn freely?  If so, brushes or a dirty commutator are the top suspect.

I have noticed that the older tools seem to run hotter than the newer ones. I think this due mainly to the fact that it is hard to hold them without blocking some of the cooling vents. The best ones are the ones with the flexable shaft. This allows you to place the tool where it can get plenty of ventalation and gives you a smaller easier to grip working tool.

Al

The flexible shaft adds a considerable amount of load to the tool, so I'm not sure that's the best option unless you're doing very light work and don't flex the shaft too much.  I have the flex shaft, but I've only used it a couple of times over the years.

Another name for bushing bearing is sleeve bearings which might avoid the confusion with brushes.

Charlie

Some Dremel models have sleeve bearings, others have either ball or roller bearings (not sure which).

This is not based on the year of manufacture, its based on the model.

An old price list that I had handy lists the model 395 as having ball bearings. Since it does not specify the type on their models 275/285, they probably have sleeve bearings.

When I purchased my first Dremel, a model 260, I was told that the 260 had sleeve bearings, and that the more powerful 280 had ball bearings.

High torque tools will increase the amount of work the Dremel must do.   Those 1.5" or larger cut off wheels quickly load the motor.  If you are doing heavy extensive work with the tool you need to move up to something a bit more commercial.