I’m not sure what the accepted wisdom is when enlarging drill holes
in stone beads, but I found something that worked well for me today.
I decided to drill larger holes through some Chrysocholla beads I
have, in order to thread them onto thicker silver wire (to make
silver links). The original holes would only accommodate 0.8mm thick
wire, which is still a little bendy even if you twist to harden it -
and I feel that more substantial wire equals nicer quality too. I
started out using an HSS steel drill bit but even though a soft
stone, it was dulling my drill bit very quickly and I only had two
drill bits of that size.
To lengthen the life of my drill bits I used a tapered, diamond
covered burr to enlarge both ends of the hole and prevent breakout
then went back to my drill bits.
After a long introduction I’ll get to the point! As my drill bit was
so dull anyway, I thought there was nothing to lose by trying to
sharpen it, so having read a couple of articles about sharpening the
cutting faces of drill bits I held the bit lightly against a cheap,
wide diamond coated burr at an angle, while the bit span in the
flexshaft handpiece. I suppose a flat faced diamond coated file
would have been better, but it put enough of an edge on the cutting
faces to continue cutting through my beads. After every few beads, I
repeated the process and restored the cutting edges. I managed to do
about a hundred beads with one drill bit.
There are probably better products for doing that, but I used what I
had and the drill bits would only have been thrown away anyway.