Drill that rock!
November 29, 2006 11:46 AM   Subscribe

How do I drill a hole through a rock? Details inside.

I'm looking for the right tool(s) and method for drilling holes in/through rocks. I'm not talking about the ground, or bedrock, or rock walls, or small pebbles to string on a neckace. I'm specifically talking large movable rocks, say 1 foot cubic.

I realize the type of rock could affect things, etc, but I assume I would need something like a drill press and then perhaps a method of cooling the drill bit, like water or antifreeze or similar. Are we talking masonry bits, or something much much different?

Basically, I would like to take a large rock, and drill a nice 1/2" hole right through it completely. Pointing me towards resources is perfectly acceptable, but most things I've found on my own have been of the "drill through bedrock to make a well" type things.
posted by Ynoxas to Sports, Hobbies, & Recreation (14 answers total)
How about an impact drill? They use these to drill into concrete. Not really sure if they have half-inch bits for impact drills, though.

I know they're not really made of stone, but a bowling ball maker/retailer might be able to help you. They have to drill into those things to size finger holes, right?
posted by backseatpilot at 11:54 AM on November 29, 2006

You'll be wanting a rotary hammer drill, like a Hilti and a big old masonary bit
posted by zeoslap at 12:01 PM on November 29, 2006

What type of stone would you be drilling?

Carbide percussion drills "may" work well enough if the stone is fairly soft and there is not a massive quantity to drill.Cracking may be a problem though.

The best solution for clean accurate holes with essentially unlimited usage would be diamond coring/drilling bits.You should be able to rent a small hand held system economically.

You could also look for a diamond bit that will have a compatible drill press shank for you drill press but you would want to go with a dry bit as jury rigging a wet system would be a pain.

Blumol I believe sells diamond coated hole saws,for another economical method.

Hilti diamond coring system
posted by plumberonkarst at 12:02 PM on November 29, 2006

Depends on the rock. It was easy to drill a hole in the limestone-block exterior of my old house using a long masonry bit and plain electric drill (not impact)—but limestone is very soft stone. Granite would probably be a different story.
posted by adamrice at 12:08 PM on November 29, 2006

My local Home Depot has a display of large impact drills where they're all stood up by their bits, in a large... rock.

As backseatpilot mentions, not sure about a 1/2" bit though. Most of them are more like 1" or 2".

But you can certainly get long drill bits that would probably work on a rock. You'd probably have to clear out the hole fairly often. And an off-the-shelf bit may dull fairly quickly. Here's the kind of bit you need - carbide tipped, masonry, works with an impact drill, 1/2" diameter, lengths up to 18" long.

But it shouldn't take anything more exotic than a standard impact drill.
posted by GuyZero at 12:08 PM on November 29, 2006

I don't think that conventional steel masonry bits are going to work. Depending on the kind of rock, you could be dealing with substances much harder than concrete or brick (neither of which are really hard compared to, say, granite or quartz). A hammer drill may make a hole that's rougher than you want, too. I think you're going down the right path with a drill press and lubrication, but you're going to want carborundum or diamond bits. A good machinery/shop-supply store (probably not a hardware store) will probably be your best resource. They will have cutting oil as well.

If there isn't anyplace local, McMaster-Carr is the standard mail-order source for odd tooling. I can't deeplink to it, but if you click on "Drill Bits" under "machining and clamping" you'll start to see what they have.

You also might want to read this article, which seems to detail the procedure (smaller holes, though):
posted by Kadin2048 at 12:20 PM on November 29, 2006

I have drilled a lot of sandstone with a hand held 1/2 inch capacity drill with a hammer drill option and carbide tipped masonry bits. What stone you are drilling is important. And wear a good quality dust mask!! Stone dust kills.
posted by Iron Rat at 12:46 PM on November 29, 2006

Use valve lapping compound and copper pipe.make a dam of clay to trap the water and abrasive. it helps if there is a slot cut in the pipe to help feed the abrasive slurry to the cut. A large tall drill press is helpful but it can be done with a hand drill and patience,use light pressure, let the abrasive do the work. If you get an inch or two an hour you are doing good.
posted by hortense at 12:50 PM on November 29, 2006

Using antifreeze as a coolant doesn't seem like a smart thing to do. Antifreeze is, after all, poisonous, and shouldn't be leaked into the environment. More to the point, though, you aren't gaining any benefits from using it. Remeber - it's designed to not freeze. You want something designed to absorb heat and carry it away.

Running water is probably the easiest option. Local stone cutters I've worked with use a regular hose clamped to their drill sets.
posted by odinsdream at 1:06 PM on November 29, 2006

Know your rocks first of all. A drill for sandstone will not work for quartz or granite. Drilling through harder rocks will require water to cool the drill bit. There are special drills to use for hard rocks but this is not typically something you find at the local hardware store.
posted by JJ86 at 1:41 PM on November 29, 2006

Using antifreeze is exactly the smart thing to do, on a budget. It is poisonous, but cleans up by dilution rather well. The benefit from using it over plain tap water is that the same mechanism that lowers the freezing point raises the boiling point. Therefore, it can absorb more heat before it boils off.

Odinsdream is right about the running water, though.

If you're drilling through reasonably soft rock (not quartzite), a Bosch Bulldog hammer drill and a long-ass drill bit should do the trick. Just remember, only put enough pressure to keep pressure on the tip of the bit - don't lean into it. Leaning into the bit with a hammer drill just wears the fuck out of the bit and cuts the hole much more slowly.
posted by notsnot at 1:50 PM on November 29, 2006

We do it all the time at work. Depends on the material, as above. Granite = hard.. marble/limestone= soft.

Part of my company's work involves strength of materials testing / blast effects studies and we core rock samples for making little 2" diameter plugs which we put into a press and crush to failure, after applying strain guages, etc.

The cores are made in a standard drill press, using diamond coring bits, cooled with water. The bits last forever, it seems. We have some that are a decade old. Slow RPM, slow feed, plenty of water.

If a core isn't needed, a coring bit is still a good thing to use for holes in this diameter size...why drill away more than you have to? For smaller holes, smaller coring bits.

For big ass holes as in granite quarry holes, we use carbide tip bits and a rotary percussion drill rig.

For sculptural holes, I use a 1 or 2 pound hammer and points, but all I carve is marble, and the holes I make are seldom precision. I DO use masonry bits with mediocre results. Often in marble, I'll just use standard drill bits (once!), for smaller holes (as in mounting/pins/etc.)

If you need more info, holler (email in profile).
posted by FauxScot at 7:23 PM on November 29, 2006

Fantastic information. Thank you all. I'm going to assess my needs more precisely and maybe contact some of you via email. This is a hobby project so I have plenty of time to review info and even do some trial and error.
posted by Ynoxas at 7:43 PM on November 29, 2006

For some reason I am having trouble marking more than 1 as "best answer", but thank you every contributor. Most answers here deserve "best answer" status.
posted by Ynoxas at 7:47 PM on November 29, 2006

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