Drilling granite wall

Very long bits can be dangerous when the hole isn't deep.

Bill

No you just don't press on.

Bill

Easier said than done.

Bill

A fraction of a degree. Don't forget, you don't need the holes to merely meet, they have to meet exactly, or there's a pinch point.

Guys I've been drilling holes through thick walls all my life and believe me, drilling from both sides is a bad option.

Also, I'd like to mention something else. The OP needs a 10mm hole. Well a 12mm or 14mm or 16mm hole contains a 10mm hole.

Bill

That assumes that both surfaces of the wall are smooth and perfectly parallel in both planes. Few walls are smooth like that. If the wall is rendered or plastered there's a random error immediately.

Bill

In my 1908 house the original paster was approx 1 inch thicker at the top and bottom of the internal walls so a large area was not even parallel to the bricks beneath.

Mine, which is an old cheap McAllister, I can vary the hammer with pressure on the bit. So surprised at that statement?

Another reason to use a shorter bit and move to longer bits where you've run out of bit in the hole.

I used one of the early Ferm SDS drills, and it had an on/off trigger with no speed control, and the bit when in chisel mode was free to rotate. So for doing something like chopping out a socket back box it was very hard to control - you could not keep the chisel in line, and could not start gently to establish a line for it to self follow.

It is a world apart from using my Makita where you can twist to chisel to whatever angle works for you and then lock it off at that angle. You can also hammer very gently if required - so you can neatly score through the skim coat on the plaster, establish the edge of your chase and then rapidly sink to full depth once you are established in the chase.

A shorter bit can help, but it can still be difficult if the drill is bouncing it all over the place. By the sounds of it, the titan linked above is more refined than many of the cheap ones used to be, which probably makes it far less of a handful.

Granite walls are generally made from fairly rough-cut blocks (wall blocks). The faces are not machined to mm accuracy.

In the vertical plane using a spirit level, but not in the horizontal plane.

Bill

What method of alignment would you use then?

Bill

No, you're talking rubbish. Or to borrow one of your favourite words, 'bullshit'.

Bill

Not applicable here but, what I envisaged reading TNPs suggestion (way back up thread) was a pair of tubes welded to arms long enough to reach the target area through an opening (window etc.) One arm fixed and the other able to slide and be clamped to a cross piece.

The tubes being long enough on the work side to reach the work area clear of cill projections etc. and also long enough to act as a direction guide for the drill.

Lot of work for a one off hole easily done as suggested but might find a use on a building site where the job recurs.

A lot of recommendations for SDS here, but I wouldn't expect it to do granite. I've encountered [other] stone that SDS just can't do. I'd go with SDS max.

The OP only wants to make a hole in the wall, not demolish it.

And you can get SDS extenders for those, but they are uber expensive.

Sorry, but this is not the case.

Bill

So you have a drill bit that will reach 97% but not 100%? That seems statistically unlikely.

Bill

You have to be totally accurate or you create a pinch point.

Bill

Pointing the drill in the right direction is not enough. The drill will have its own ideas about where it actually wants to go depending on the variability in the stone or brick. John