How To Cut Hole in Granite for Round Sink

LaurieP · #1 01/12/08, 07:50 PM

I have some granite that is 1.5 inches thick that I want to cut a hole in for a round bathroom sink. I'm using two 12 inch wide sections placed side by side for the vanity top so I do have access to part of the hole from one side of each granite piece. Anyone have an idea what I can use to cut the granite? I have a sawzall if there's a blade for that, a zip saw if there's a blade for that, and a router if there's a blade for that.

WisJim · #2 01/12/08, 07:53 PM

My son does this for a living. He uses various saws and routers with special diamond covered blades. It takes him a couple of hours to do a sink cutout in a granite slab, and I think he gets premium wage for it as he does it better and faster than other fellows doing that kind of work. If he were home I would ask him for details, but he's not available for me to ask tonite.

LaurieP · #3 01/12/08, 09:34 PM

Thanks for your response. If you do get more information from your son, I'd love to hear more. I haven't even been able to find anyone in my area who can cut granite.

canfossi · #4 01/13/08, 07:18 AM

I would take it to a place who cuts granite. Also if there is a narrow area on the front and back of the couter it has to be reinforced. The company that installed my countertop cut it at the factory. I know it may cost a couple hundred to cut but I would have it done professionally so things don't get messed up. It will have to be wet polished after it has been cut. Chris

LaurieP · #5 01/13/08, 07:32 AM

We checked on having it cut. The local company won't cut granite that isn't purchased from them.

sugarbush · #6 01/13/08, 07:43 AM

I think you will find that you will not be able to cut it yourself. Even if you could find the proper sawblade, it will cost too much for a one time use.

Windy in Kansas · #7 01/13/08, 08:04 AM

Before abandoning such a project I would go for broke, pun intended.

There are now diamond coated blades available for angle grinders. However I would probably opt for a gasoline powered unit that is used for concrete cutting.
Make angle cuts which converge to remove a large portion of the needed area, then nibble away the remainder with small cuts.

Finish with grinding wheels and polishing wheels. Doubt you will get anywhere near a professional like job so hope you have a sink rim that can cover at least some of the cut edge.

texican · #8 01/13/08, 10:26 AM

Having a free piece of granite is great... the problem is, if the granite is not usable in the current form, it's just a piece of rock... getting it into a form that you need can cost real money, if you have to buy the specialized tools to machine it. My lifelong friend has a granite business, and he charges a fortune for his pieces... look in his company shop and you'll see very expensive tools...

If I wasn't afraid of losing the pieces of granite, I'd try a wet saw first... outline your cut with magic marker or grease pen... cut straight lines with the wet saw to the line... then make another one 1/4" or less away... make dozens of parallel lines right up to your half moon mark... all the little pieces would flake off easily then... Have the piece turned upside down when you're cutting, so that when you flake the pieces off, it should be very close to the 'line on top', so when you put the sink in from the top, all the little ragged edges are covered... if you still have some roughies, use a angle grinder with a hard grinding blade (carborundum?).

It 'can' be done... just difficult.

If you check around, you can find precut granite vanities very cheaply online...

good luck

farminghandyman · #9 01/13/08, 06:19 PM

I had a nice post done and it went to cyberspace, some where,

here is the jsut, of it,

for a round sink a special diamond blade is use, in a variable speed grinder,

http://www.defusco.com/
this company has three videos that are to show how to do it your self, the second one will show very clearly how to,
http://www.defusco.com/How-To-DVDs-&...654/index.html

the blade they recommend is,
http://www.defusco.com/Diamond-Produ...489/index.html

on you tube there are a number of videos, as well,

this is jsut one
there is a link to another company at the end of the video,
http://toolocity.com/ looks like a good place for possible supplies,
this one is good but not round or oval

general search,
http://www.youtube.com/results?searc...&search=Search

I would guess one could make a series of straight cuts, with a 7" diamond blade, in a skil saw, in a basic shape, and then work them out, with the edge of it into a round shape, using the edge of the blade. If it is a top mount sink.

LaurieP · #10 01/14/08, 07:25 PM

Thanks a lot to everyone who posted a suggestion. I had a Miller wetsaw with a diamond blade and I tried the many different cuts about a quarter inch apart apart and actually got the large section cut out of the center of one of the slab. When I tried turning it over and cutting out the hole from the other side, I cracked the slab at what appared to be an inherent weak spot. I imagine that happens occasionally even to even the most highly-skilled stone workers. I figure there has to be a way to do it though, and I'm looking at the links farminghandyman suggested. I'm on the same page as Texican and I'm not going to quit until I figure out how to cut that rock. I'm still open to suggestions.

Big Dave · #11 01/14/08, 09:26 PM

Hey doesn't granite radiate radon?

Quint · #12 01/15/08, 01:20 AM

No. It's slightly radioactive as are many natural building products.

Windy in Kansas · #13 01/15/08, 09:53 AM

Quote:

Originally Posted by Quint

No. It's slightly radioactive as are many natural building products.

Does the radioactivity help one find the kitchen at night in the dark?

Does it have enough radioactivity to kill off meal moths and spice insects?

Hm, might be on to something beneficial here. lol.

texican · #14 01/15/08, 10:27 AM

I would think a granite slab has probably degassed by the time it's travelled halfway around the world, and sat in different warehouses for months, if not years...

Just imagine if it were still a little 'hot'..... counter's always warm!

canfossi · #15 01/15/08, 03:24 PM

Radioactive! I didn't know that, so that's why I've been glowing for the past month. The radioactivity must be coming from my granite countertop. Chris

**highlands** · #16 01/15/08, 06:57 PM

I do this sort of thing all the time. We get junk granite from the garbage piles of the local quarries and stone cutting sheds. $25 for a 12 ton truck full. To that end I spend the money on a few tools. It doesn't take much:

Hammer Drill - Mine's a Makita $329, works great, many brands. The bits cost $10 to $75 each.

Diamond blade for skillsaw - $17 each - work wonders on a regular skillsaw. Use water.

Garden sprayer for spraying the water.

Feathers and wedges.

Diamond jig saw blade for my jig saw.

Diamond grinding pads for angle grinder 4"

Diamond sanding pads for random orbital sander

Sealer & wax

Brick set

Point chisel

4 lb sledge hammer

Mason's hammer (square one side, flat point the other side)

It's great having the right tools when you're doing a project - those do most everything for rock. I also have a tractor with hooks welded onto the buckets for lifting and moving rocks too big for me to handle.

One other thing I would consider getting would be diamond router bits. Someday. I've lived so far without it...

Back to your project...

1. Drill a hole in the middle and set a pin.

2. Drill a hole out at the perimeter of the circle to be cut.

3. Wire the jig saw to the pin.

4. Cut out the circle starting at the outer perimeter hole outside point and keeping it wet. It's slow work. Faster with light colored granite, much slower with black. Keep the pressure and angle even. Do not rush.

5. You'll then want to round off the edges, polish it up, etc.

I have an alternative way I've designed that I've not tried yet but have started building the parts up for. Basically the stone rotates on a lazy susan past a spinning bit. It should work but I haven't tried it yet.

Have fun, work safely.

Cheers

-Walter
Sugar Mountain Farm
in the mountains of Vermont
http://SugarMtnFarm.com/blog/
http://HollyGraphicArt.com/
http://NoNAIS.org

sbin · #17 01/15/08, 07:19 PM

I cut 3cm. granite with a $15 diamond blade from home depot in a circular saw.pouring water on the bkade from a 1l bottle to keep the blade cool snd the dust down. A variable speed grinder,carbide grinding stone and a set of polishing pads are needed to shape and polish cut edges. The job is not difficult with a liitle practice. Be careful, granite breaks easily.
Bought several hundred dollars worth of tools 10 years ago to make counter tops for my kitchen and have done 30+ granite jobs since for friends and family.