[Robert t]

Have recently picked up a job finishing a bathroom. I have done construction for over 20 years but have never seen tile this hard! I have drilled hundreds if not thousands of holes in stone, conc, tile, slate,so I have experience. I used glass/tile bits, carbide, and SDS hammer drill bit, 7 in all only managed 2 of the 8 holes I need. Tried start small and work up, tried slow speed with lots of pressure. It's a vertical surface (shower door) so won't stay wet to cool the bit. Installer deceased so I don't know what kind of stone tile it is,homeowner does not know either. Need 6 more 1/4 inch holes to complete. Considering relocating holes to grout joints but would have to re-drill slotted holes in shower frame. Any one been here before?

 

[bbo]

i bet a pic of the stone would garner a couple good guesses.

diamond tipped bit would work best. use a spray bottle to keep wet. you definitely need water to cool it down and help remove the stone dust. trying anything to drill this dry simply will take excesively long time.

 

[zircon]

Probably porcelain tile. Agree diamond core bit is the best. It's hollow and looks like a short piece of tubing. It will want to walk when you try to start the hole. Wedge a piece of wood with a vee on the top against the wall with the bottom of the vee where you want the hole. You will need two hands to hold the drill so you need an assistant with the spray bottle.

 

[Canarywood1]

Just be sure and get the right bit,they come in different flavors,glass,tile, concrete,asphalt, and what you need porcelain tile.

Linky http://www.contractorsdirect.com/Diamond-Hole-Saws-Core-Bits