why core drilling is so slow ?

(This is particularly a problem if drilling through granite, which I once spent a summer doing).

http://www.theoildrum.com/node/5629

And if you push too hard on the bit, then you can push the diamonds down into the matrix, so that the matrix is rubbing against the rock, rather than the sharp diamond edge, and this slows things down. (This is particularly a problem if drilling through granite, which I once spent a summer doing). And so the question came as to how to make this sort of drilling faster. We would still need the diamonds, to cut into the harder rock, but couldn’t we find a better way of making an artificial diamond – after all we only need to have it on the surface of the bit, and perhaps just apply it as a coating to a bit.