Drilling through stone

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Freshta

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Raleigh, NC
Funny that I've been doing electrical work for 25 years (mainly commercial/industrial/controls) and I've never once had to drill through stone for any reason. I have a customer wanting a GFCI outlet installed on the front of the their house to provide power for low voltage lighting and the front is stone. Any tricks to drilling to ensure it doesn't fracture?

Thanks,

Tony
 
the front is stone

1/2" thick facing stone, 3" river rock, or 1/2 ton granite boulders ?

Big difference in technique to drill.

Bosch bulldog (or even HF equivalent or rental) for larger stuff or air impact drill.

If just facing 'stone', 1/2" drill with carbide bit.
 
I would do it in steps if you think it may crack.

Drill 1/4" with sharp carbide/masonry bit
Drill 3/8" "
Drill 1/2" "
All done with a rotary hammer drill

Up to the size you need for cable entry. 1/2" should do it for that and just what ever size your mounting screws are for the box.

Any chance you could drill through below the stone and conduit up to the box?
Or you could find a grout joint for the cable/wire and drill through that.
 
...do not start to drill with the hammer action engaged, it will fracture if thin stone. Start drilling without hammer, similar when drilling bathroom tiles.
 
jusme123 said:
...do not start to drill with the hammer action engaged, it will fracture if thin stone. Start drilling without hammer, similar when drilling bathroom tiles.
Click to expand...

Yep, I should have mentioned that. I don't ever start on hammer action even on my cordless stuff. Just start it slow on drill, then when I have made a good start I switch to hammer.
 
I have lots of experience with bricks, blocks and rocks.
If you post a pic I can tell you how I'd tackle it.

Thought: have you considered surface mount box?
The LV landscape lighting transformer is going to be surface mounted anyway.
And that way you only need a small hole.
 
As you drill save the stone dust.
Any cracks or imperfections can be hid.
Put a little 100 percent silicone,( clear.) over the cracks. Then sprinkle the dust into the silicone, tapping it in until it sticks.
 
Freshta said:
Funny that I've been doing electrical work for 25 years (mainly commercial/industrial/controls) and I've never once had to drill through stone for any reason. I have a customer wanting a GFCI outlet installed on the front of the their house to provide power for low voltage lighting and the front is stone. Any tricks to drilling to ensure it doesn't fracture?

Thanks,

Tony
Click to expand...

Hilti makes x-head hammerdrill bits that cut smoother and faster than traditional bits.

If it's stone veneer, a diamond/carbide holesaw will prevent chips. Drill from the outside in. Dont drill near an edge or corner, and if you can drill a groutline, go for that.

If it's stone on block, you will need a long bit (18"). If you have to use an extension, make sure your hole is large enough to get the extension thru.

Pull out the bit often to clear dust/chips, and keep that drill level or it'll bind and try to break your wrists.

Carry an extendable magnet with you to check for rebar/lag bolts in the hole.

You may also need a long wood boring bit if you are going into the band or other wood behind the block/stone.

eta: the largest hole you can drill without sds-plus drive is 1 1/8". Difference between a $250-$350 10lb dewalt or bosch hammer drill or a 25lb rotohammer that costs 2x as much
 
Bosch Carbide Hole saw

Bosch Carbide Hole saw

These can be run wet and they work very well.
After dealing with the sight of very many penetrations in cinder block at this facility that were very badly done with hammer drill bits, I wanted something that would make clean cuts in cinder and these work perfectly. They also make diamond grit models that run on the same mandrel.
While everyone else made a total mess of the cinder, these give a very clean cut.
 
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