drilli9ng stone

[butch]

i am trying to drill into a riverbed stone imported from mexico. gray to black , fist size, used as decorative stone in gardens. i need a 1/2" hole 1" deep. tried a glass bit, carbide bit, small starter holes but this stuff is so hard it takes a lot of pressure and oil and then it breaks in two. it heats my bits to a dull red before they penetrate. ruined 5 bits and 5 stones so far. anyone have experience that might guide me it would great.  thanks  butch

[Hillbilly]

You may have to use a masonry bit and just take it slow and easy. It's bound to go faster and easier than the traditional method of spinning a cane stem by hand with sand under it.

[mullet]

  Use a masonary bit on low speed with water in the hole and on the bit. If it is real hard use oil. When it starts to smoke, stop and let it cool down

[DirtyDan]

You might try using a diamond burr to make a small hole first and then use small masonry bits until you get a hole big enough.

Dan