I picked up a handfull of dental drill bits for next to nothing. 3 for a buck. The heads are small, tiny, little things, you can barely makeout the shape with the naked eye. They are great for detail work, BUT, you still need to be careful about tearing (as has been said). The location in town is called Active Surplus. I don't know how to describe it. Surplus, Recycler, odds and ends? The store has everything from pen springs to aluminum ingots, electronic parts and medical surplus. My googling involved the words "dental drill, Gorilla Costume, acrylic and carriage bolts"
1) Be patient, and move the tool as light as posible and as slowly as possible. Instead of carving, it's more like sanding away material.
2)Grab some scraps and prep them diffrently. Some methods work better with those bits than others, and your actual leather is another variable. Use one bit on the scraps to get a feel for the cut and the rate of dulling. Pay attention to your pressure and speed.
3) Some rotary tools have a clutch that can "theoritically" be adjusted. If you are mechanically competent you can open it up and see if there is a way to adjust it. (This will void warranty, is mildly dangerous, and may anger your personal deity). I can't tell you how much you need but my gauge is this:
With it spinning, I touch the bit to my fingertip. It should be light enough that firm pressure will stop it, but will begin to cut (abrade) if you pull back slightly. Or you could use a scrap piece of leather and test your setting (that is probably much smarter)
4) If you can't adjust the tool itself, you can go a bit light on the locking collect. This is not consistent, but it's better than nothing. Either way your tool should get to a point where if its not cutting it will stop (like when it's about to tear)
Have fun. But the more you practice the better off you'll be before attacking an actual project.
