Here's something from the Chipping Away wood carver's newsletter I found interesting. You shouldn't let your flex shaft handpiece hanging when not in use.
Huh. I loop mine up and over the motor hanger - leaves it horizontal and up over my head. Easy to reach when I want it, out of the way when I don't.
Did some early morning work on Sunday while the ever-indulgent wife was sleeping in and forgot one small disadvantage of my setup: I'm actually just beneath our bedroom. Right under my side of the bed, in fact. The flex shaft's hanger is screwed into a roof joist in the garage. Of course my roof joist is the bedroom's floor joist. It might be nice and quiet for me but I was reminded rather firmly that it makes a lot of noise up above.
vibration aint for everybody, i guess. be careful, you may be cookin yer own breakfast every time you use the flex tool. as for overheating-- never noticed it when i used the foredom.
Never had a problem with either my handpiece or the flexshaft heating up in 30 years, although I don't use them continuously. Wouldn't be a bad idea in taking it down to clean out the sheath, and for general inspection. I do have some high tech grease for the purpose, but, again, mine doesn't heat up.
After a lot of years running and servicing Foredom flex-shafts (not nearly as many as Brian), I have seen a couple over-heating handpieces. I never really figured out the exact cause of the first one, but found that by out-smarting the handpiece by installing aircraft quality sealed bearings (with well greased ball bearings), made it get extremely hot even faster. Going back to the shielded bearings (with relatively dry ball bearings) took the warmth of the handpiece back to a useable level.
Too much lube in a Foredom hand piece is not a good thing, but it takes significant heat to liquify a good quality shaft grease so I'll continue to hang the hand piece "the wrong way".