Homebrew PCBs

I just tried to grind a simple cutter out of a broken carbide drill.
The 1/8th inch shank is just the right diameter for M3 mounting holes.
I've seen pictures of cutters on the web where half of the drill is simply  
ground away flat, so i tried that.
I used a white grinding wheel in a plain (dry) bench grinder, and it was  
slow going, but the result works well enough to drill mounting holes.  
There is some burr at the exit, but compared to the commercial drills this  
tapered drill does not stall the small spindle i use for PCBs, which is a  
plus.

That drill material is very tough stuff, and i don't have the right wheel,  
but it worked OK for a first try. Does carbide lose hardness if it gets  
too hot like hardened steel? I didn't bother to cool it much and it got  
orange hot quite quickly. It was only a trial so i do not mind if it is  
weak.


ST