Using granite blocks for a supporting base for a cnc router ?

[the great waldo]

Hi Chaz
Yes I got that. No worries I won't be shifting granite gravestones about the place. Just out of interest does anyone on the forum any experience of drilling granite? I want to drill a few 12 mm holes through the slabs which are 25 cm wide. I've got a pneumatic hammer drill.
Cheers
Andrew

[phill05]

No you don't want Pneumatic hammer drill you need a diamond tipped core drill (PCD) and lots of water.

Phill

[JAZZCNC]

Just out of interest does anyone on the forum any experience of drilling granite? I want to drill a few 12 mm holes through the slabs which are 25 cm wide. I've got a pneumatic hammer drill.

Whatever you do, don't turn hammer on it will crack it like Eggshell. While it seems rock hard Granite actually fractures very easily if handled wrong.
Ideally, you need a Slow speed Drill with high torque and like been suggested PCD Core bit and lots n lots of clean water. Do not try cutting without Water with PCD otherwise, they just fail quickly.

[the great waldo]

Hi All
I think i'll give up the idea of tie rods and just epoxy or cement the two blocks into a steel welded frame. Does anyone have any ideas as to fixing the base onto the granite. I figured just drilling some holes through the granite and connecting them with bolts and t-nuts into the ali extrusion. I've attached a couple of photos of the base plate. It's machined flat the base is 20mm thick and the ali extrusion is 60mm square. All comments gratefully accepted

cheers
Andrew