Odd request perhaps. I'm having a new clock case made to replace one that has been damaged. It will be made from 20mm thick granite or maybe marble. The front panel of the case is giving problems. This is 190 x 205mm and contains 2 apertures, first is 100mm square and the second is 20mm beneath the first @ 50mm wide x 35 high. Cutting the panel to size and the first aperture are no problem. My stonemasons mechanised tools are too large to make the smaller aperture. He is more used to kitchens/bathrooms/fireplaces etc. He can do it by cutting/shutting/gluing but this would leave unsightly joins on the front of the case, I would prefer not to use this method. Both apertures are filled by glazed metal frames so the finish to the apertures need not be polished, although they have to be quite accurate. I'm wondering about having go at making the smaller hole myself.
I have woodworking experience and some metalwork but no masonry knowledge. As the material is very brittle I imagine conventional chiselling would be a non-runner. An alternative might be removing most waste by drilling and cleaning up with a suitable tool. Anybody know of (1) a suitable tool or (2) any alternatives? Hope the above makes some sense.
Many thanks
Nick.