How to drill 1/4" holes in granite

[joyfulartist27]

I am an artist looking to drill 1/4" holes in small chunks of granite. Is this something I can do for myself with relative ease, with an impact hammer or by renting a drill press? Do I need to use a special drill bit and/or water  to keep it cool? Or should I look for a professional, and if so, do you have any suggestions? I asked at the granite supply place that gave me the granite chunks but they said they didn't have the time even though I was willing to pay and it would probably take 15 minutes max to do the 15-20 pieces I had. Thank you!

[Mark D.]

How deep are these drills?
How thick is the granite?
Are you drilling into the stone or through?
Must it be 1/4" or could you go up to 3/8?
Let me know please, I can help.

Mark

[joyfulartist27]

Hi Mark,

The chunks of granite are anywhere from 3/4" to 1-1/2" thick. The holes do not need to go all the way through. I am using them as a base/stand for artwork supported on a 1/4" copper tube, so the tube will be inserted into the hole with epoxy to keep it in place. Does that answer your questions so you can help me?

Thanks, Pegatha*

[Mark D.]

Yes it does. Now I know a core bit will not work as you are not going through the material. The only thing problematic about this is the hole size, but based on your application description you should get a 1/4"  wet non core drill (think forstner bit), which we stock. You can run it on a wet polisher and it will drill your holes into the stone leaving a cylindrical hole. then allow the stone to dry before epoxying in your rod. It is listed with our core bits but it has a plugged end so it is really a noncoring bit for  granite. See this link:
http://www.defusco.com/14%E2%80%9D-wet-diamond-stone-core-bit-p-1400.html


I would mask off around the hole to make sure the glue does not color enhance the stone, especially if it is unpolished. If it is already polished use a mercaptain epoxy which will not stick to the polished surfaces.
See this link:
http://www.defusco.com/instant-install-minute-epoxy-32oz-knife-grade-p-2423.html

Mark

[joyfulartist27]

Hi Mark,

Thanks for all the info and I will check into getting the bit and epoxy you suggested.

One question: what is a wet polisher? Is it something I can rent or are they reasonably priced to purchase and do you sell those, too?

Out of curiosity, why is the size of the hole a problem?

Okay, and while we're at it - in the future I was thinking of using a couple layers of granite as a lamp base - using either 1/2" or 3/4" copper pipe (whatever will fit the light socket at the top) - drilling all the way through to the bottom for the pipe, then creating a groove for the cord to come out at some point. What is your advice for drilling all the way through with the bigger holes and creating the groove at the bottom. If the groove is too difficult, I suppose I could use a wood or metal base below the granite, but I'd prefer not to. The pieces of granite will be slightly different sizes and offset so I'll need to glue or epoxy them in place - should I use the same epoxy you already suggested or something else?

Thanks for all your help. I'm learning a lot.

Pegatha*

[Mark D.]

Wet polishers are like grinders with water feeds that come through the center axle (arbor) to feed water to the products they use (wet polishing pads, wet grinding tools, wet core bits). You can see them on our site at:
http://www.defusco.com/power-pneumatic-tools-wet-stone-grinders-polishers-c-78_31.html

The size of the hole is only a problem because it is so small, and if you had tighter tolerances it would be a real pain to make a 1/4" rod fit in a 1/4" hole. You are using epoxy as the bond so you don't have those tolerance issues.

On the 2 ply bases (a lamination) epoxy them together, core drill through them and use a diamond blade to cut the slop on the bottom for your cord relief. I would then glue a piece of felt over the finished base to contain the cord and prevent the granite bottom from damaging the table it sits on, but that's just me.
For the bases that epoxy will work just fine, but if you are purchasing quantity there are other products which cost a little less and react a little more slowly.

[Michelle]

Hi,

I'm a newbie here, and am hoping for some sage advice on drilling 1/4" holes in granite - specifically, a granite slab shower that's almost 3/4" thick.

I called the people that put in this shower, to ask them if they could send someone to drill a few holes in the shower wall, to attach a vertical bar for a sliding showerhead. It involves drilling three holes in a triangle, about 1" between the holes, and then another set of 3 similar holes 2 ft below the first set. The holes look like they can be about 1/4", to accomodate the plastic sleeve that the screw fits into. These holes will go right through the granite.

The granite people sent their service guy, who attempted, with an ordinary drill, a water bottle, and a carbide masonry drill, to drill the holes. He could hardly make a dent in the granite, and said he would come back tomorrow with a more powerful hand drill (hammer drill). He said he hadn't had to drill small holes in granite before. As you can imagine, I'm worried that the guy is going to crack the granite. I mentioned diamond drill bits to him (I'd been reading up on the internet before he came) but he didn't seem too impressed, saying they were overly expensive, and that he'd need one drill per hole because the diamond drills burn up so easily.

I'd like to know please, what sort of drill, bit and method would be best for drilling these holes.


On a related topic, but slightly different application, I also have a heavy corner towel rail (weighs 19 lb) that will be affixed to (through) the granite on one side, and the other side will be fixed to an ordinary drywalled wall. (There are support beams in the wall, behind the drywall, and behind that part of the granite wall). There will only be one long 1/4" screw that goes through the granite (at the top right corner of the towel rail), and another similar large screw that goes through the granite at the bottom right corner of the towel rail. Two similar screws will go through the drywall and into the supports on the other side. That's all that will support it. I'm thinking the minimum hole size would be 3/8" for that. (I'm afraid of the screw being pulled down onto the granite, and putting pressure on the granite). What do you think?

[Mark D.]

If the granite company you are using doesn't know what a diamond drill bit or coring bit is, or thinks a carbide bit is a better idea, then they are not fabricators. They may be tile setters doing a granite job for you.

I am going to repost the section on coring small diameter holes in granite. Here it is, and this should take care of that issue.
Yes it does. Now I know a core bit will not work as you are not going through the material. The only thing problematic about this is the hole size, but based on your application description you should get a 1/4"  wet non core drill (think Forster bit), which we stock. You can run it on a wet polisher and it will drill your holes into the stone leaving a cylindrical hole. then allow the stone to dry before epoxying in your rod. It is listed with our core bits but it has a plugged end so it is really a noncoring bit for  granite. See this link:
http://www.defusco.com/14%E2%80%9D-wet-diamond-stone-core-bit-p-1400.html

When you have cored your hole and you install your anchor I would seal the heck out of it with silicone caulk to prevent water seeping through and creating mold underneath. You can use that for this application for the part of the rail that is going to be suspended from the granite, and as long as your anchor is strong enough for the piece it should be no problem.
As far as the part going through the drywall, I am no expert on drywall, but I think you should find a stud behind the drywall to set the anchor to. The reason is that if people pull on this or you hang stuff on it then it will be acted on by an occasional force and the result will be that the anchor eventually could pull out of the drywall.
On the granite side, a 1/4" screw in a lag style anchor is probably rated at 30 or 50 pounds which would be ideal for this application.

If you have any other questions please call me at 800-289-6834.
Glad to be of service,
Mark