uxcell PCB Drill Bits 1mm Tungsten Carbide Rotary Tool Jewelry CNC Engraving Print Circuit Board Micro Drill Bits 1/8 Inch Shank 10 Pcs

I use these bits in the 1.0mm size to open up predrilled holes on freshwater pearls. I've tried many different bits with a micro rotary tool, and most took a long time to drill, heating up the pearl and causing internal scorching. These bits are much sharper and drill 10x faster, and hold on much tighter. My only complaint is that some seem to be created with more fragility. I've had 2 break mid shaft in a row after 1 or 2 uses only to have a 3rd last well over 20 drills before snapping. But the ability to drill cleanly, quickly, and precisely is why I will keep buying these, despite the problem with breaking.

These work great with a high speed drill. I use a Proxxon bench drill running at 8500 rpm, works fine for drilling pcb boards.You will not be able to use this product successfully at low speeds, and with a hand held drill you will probably snap the drill bit when you have drilled a hole and are extracting the bit out of the hole. Been there, done that.

reasonable performance cutting hard wood on my CnC machine

Broke all bits and never finished job. Ran machine at lowest feed rate and -0.5 Z depth.