I have a Proxxon miniature power tool, a bit like a Dremel but allegedly better made. It's pretty good, handy for drilling small holes in baseboards and running a small diamond saw which I use for accurate cutting of rail ends.
But: There is no insertion mark on the arbors, and if you push them too far in you end up cutting the rails at an angle.
If, on the other hand, you don't push them in far enough, then the vibration at speed is sufficient to cause the arbor to bend, pull itself out of the (tightly fastened) chuck and fly off at great speed into your eye. If you are lucky you will be wearing polycarbonate safety lenses and your eye will only be cut and bruised, like mine was. I have found some pieces of the lens: it looks like a direct hit in the middle of the eye. The ophthalmologist looked at the eye and reckoned the force was very, very close to the level at which the eye would have been destroyed. He asked me if I knew how lucky I am. Yes, I do.
Needless to say I have just ordered a replacement (kitemarked) lens. In fact I've decided to go the whole hog and have a pair of safety specs made up, with side guards and all. I always used to have a pair of prescription safety glasses, but stopped bothering when I stopped doing "dangerous" workshop work. Little did I know how dangerous it could be building a model railway!
Let's be careful out there...