Novalina, You should check the Orchid archives for a lot more
about drilling in stones. But......here are a few little
things you need to know.
If you are drilling such long holes and many of them....you best use
sintered diamond bits...not coated. The coated are fine for a
little job here and there but they wear out quickly. The sintered
are quite a bit more expensive but will last a long time if used with
When drilling, you need to use an in/out motion. You must
completely remove the drill from the hole every few seconds to allow
the water to go to the bottom of the hole and wash out the swarth.
That might be difficult in a long hole so one thing you can do is to
drill half way from one end and then drill from the other the other.
Otherwise, you seemed to have a good grasp of what needed to be
done. Keep at it. If you want to do a LOT of holes, look into
purchasing a sonic drill. Cheers from Don at The Charles Belle Studio
in SOFL where it is already summer and where simple elegance IS fine