Thirdly, use the fastest speed possible. This helps disperse any
fragments of glass from the hole and reduces the temptation to lean
too hard on the drill to make progress. lastly, try and mark a
groove on the kerf of the drill bit to allow fluid to remain in
contact with the glass/diamond interface and lessen local heating.
Here is the old method for drilling obsidian. Take a brass rod of
required diameter. Put the end of the rod against old file and give
it a sharp blow with a hammer. Rod end now have sharp indentations.
Dip end of the rod in oil and sprinkle some diamond abrasive on it.
Abrasive should adhere temporarily. Bring this end against some flat
chunk of iron and give it another blow with a hammer. The
indentations will close up entrapping some diamond abrasive. You
have just created a drill, which is more superior to commercial ones.
Abrasive is distributed very sparsely and such drill will not
generate a lot of heat. Also brass is much better heat conductor
Mount your work on the bottom of some container. Mounting it with dop
wax is a great advice. Use drill press. Fill container with water. I
recommend the slowest speed possible. Bring drill in contact with the
surface and arrange for constant pressure. The simplest way is to
hang some weight from the handle bars used to advance drill head. It
is better to use smaller weight, then larger one. 5# is good starting
Once setup, no attention is required. You can go an do something
else, while it is going.