I've used these for several jobs in only a short time. They are small drill bits, but that is the point of a MICRO set. I have used these to create holes to insert wiring on 1/48 scale radial aircraft engines, to hand-build 50 cal machine gun ports that were inexplicably absent on a WWII fighter plane, and to repair an old P-51's broken landing gear strut by hollowing it out to insert a small metal shaft. They worked flawlessly, and I would not hesitate to recommend them for this kind of crafting.