Drilling

The most long-lasting and high-performance hollow drill bits have diamond chips around the drill tip. They cut a ring in a granite block, producing a core. The core can be extracted using an additional core removal tool. The service life of a diamond drill bit depends greatly on keeping the drilled hole clean, cooling, and maintaining a balance between drill pressure and rotational speed. Wear can be counteracted by re-sharpening the tool.

Classical sources of error and obstruction when drilling granite include an incorrect drilling angle and a lack of cooling lubrication. Drilling at the wrong angle must be avoided, i.e. the angle of incidence of the drill must be as close to ninety degrees as possible. Users should check for the centred, clean running of the drill, which can easily be verified visually at slow rotational speeds. If crystals of non-uniform size emerge from the drilled hole or during cleaning, the cooling water feed should be increased. Excessively high drilling pressure can warp the cutting end of the bit.