I want to drill a 2-3cm diameter hole in a ceramic tile. There are diamond-coated hole saw bits, and I read that a cordless drill is recommended if water is used for cooling. I own a 10.8V 30Nm torque drill, but there are more powerful 45 and 85Nm versions too. Is my drill OK for this, or should I invest in a more powerful one?
I'm not a professional, but have drilled a lot of holes in masonry. For a tile, I don't think that the torque will matter much, just chuck it, set it to high speed and drill. Drill a test hole in a piece of scrap first, so you will know what to expect. I think your toughest problem will be trying to get the hole started on your center accurately. Nicking the tile with a punch may help.
Drilling an 8" x 3/4 inch hole into 10 year old concrete will require a bit more torque.