Drilling Holes in Granite

[Choada_Boy]

Seriously. I have to drill 9/16" holes in a four inch thick slab of granite without breaking it. Questions:

 

1) Rotary hammer or hole saw?

2) What's the minimum distance I can space the holes using a rotary hammer and not expect cracking between them?

 

Any other advice?

[JosephH]

Wet, diamond core bit. Don't hammer drill. In fact, just take it to a countertop or headstone outfit and have them do it.

[Choada_Boy]

That's what I was figuring I'd need to do. Renting the hole saw is pretty spendy for eight holes. Thanks!!

[tvashtarkatena]

Beg to differ. Hammer drill works great. Done it a bunch a times. You're not gonna crack a 4" thick piece. Granite drills like buttah, btw. Regular hammer drill bit for granite - no diamond required. Water cooling advised.

 

Now basalt....

 

 

Edited November 1, 2010 by tvashtarkatena

[Choada_Boy]

Hmmm. 9/16th?

[tvashtarkatena]

Oh shit...didn't catch that part. No experience here with that size.

 

 

[ScottP]

http://www.ihs.issaquah.wednet.edu/teachers/fine/new_page_45.

[Off_White]

I'm with Joseph on this one, drill press would be nice too, and patience is required. I did this in a lapidary shop at TESC a long time ago.

 

You might do okay with the roto hammer, but I bet the hole will crater from the backside when the bit goes through, and the hole won't be as tidy.