Cutting Granite

[Mike OMelia]

OK, not wood, but thought someone here might know. I have to expand a hole where my cooktop is to accomodate a new cooktop and downdraft ventilation unit. The part to remove is about 29" long by 3" deep. Finishing the stone face is not needed. What tools (bits & blades as well) do I need?

Thanks.

Mike

[Henry Ambrose]

A Rotazip with a diamond wheel will do it. It will be very messy - a helper with a shop vac held close to the cut will suck up some of it. Clamp a piece of wood along the cut to help keep from over cutting.

[Jamie Buxton]

Or a 4" angle grinder with a diamond blade. That's what I see the pros using. You can get the blades at Home Depot and the like. The pros cut the granite outside whenever they can, because it makes nasty dust -- gritty stuff, unlike nice wood dust.

[Maurice Ungaro]

Mike, the CONTINUOUS RIM diamond blade is a must.
Also.....WEAR A GOOD MASK and VENTILATE WELL. Granite dust is worse than MDF dust. More than a few folk songs were written about the old "hard rock" miners, and their resultant respiratory problems - silicosis I believe.

[Jim Rimmer]

From videos I've seen I can only imagine the amount of dust that will be generated. A few years ago we had to have a couple of tiles replaced in the kitchen and the moron that was sent to do it grabbed a grinder and took it to the grout (while no one was home) to remove the old tile. That dust went EVERYWHERE, even inside the cabinets. So, do all you can to mitigate the dust is all I can suggest.

[michael case]

Maurice is right Granite dust is dangerous!

[Maurice Ungaro]

IF you can drip water on the blade as it is cutting, you can negate a lot of the dust problem. But, as the granite is already installed, the water trick may be...well....tricky.

[Mike OMelia]

Maurice, what is the blade attached to? (the tool).

As for the dust, thanks for the heads up. I will build a "tent" around the island with plastic and simple framing.

Mike

[Jeremy Brant]

I haven't used a rotozip before, but for rough cuts a diamond wheel on a 4 or 4.5" angle grinder works fine too. Again though, lots of dust.

[Maurice Ungaro]

Mike, the Roto-Zip may be under powered. Personally, I try to cut my stone with a circular saw (Skil-saw type). More power, bigger blade. The bigger blade cuts more efficiently, and you can make a quicker job of it with the increased power.

If you are tenting the area, try to use water to mitigate the dust. Simply have an assistant use a pitcher, or 1 gallon jug (if a garden hose is not applicable) to place a small stream of water in advance of the cutting wheel. This also helps cool the blade. Again, with an interior job, this may not be practical.

[Mike OMelia]

Skil-Saw? Really? So the idea is to make several passes, and increase the depth each time?

Yes, indoor project. Water is out of the question.

Mike

[keith ouellette]

I had to cut and polish some granite for a fire place hearth. I used a circular saw and a diamond blade.

Don't use an angle grinder if you want a very straight cut.. Unless you have a large one it won't really cut 3" anyway.

If it is a plunge cut the plunge part will take a while so be patient. after that it's a piece of cake. maybe 2 passes. what I cut was only 2" thick. 3" seems like a really thick counter.

Do you have to do it inside? If you do you should use a 120v dc, vented outside and have a helper hold flexible pipe to catch the dust.

There will be a lot of dust and a shop vac won't cut it unless you don't mind dusting off everything in that part of the house.

If you can section off the kitchen with plastic it would be a good idea to do so.

[Rick Hall]

If you hold a large grouting sponge that is fairly damp right at the back end of the spinning blade it will work well to catch most of the dust as it comes off. Go slow and re-wet the sponge every few inches. Just have to be extra careful since you are playing with water and electricity. I have a gfci protected power strip I use when I do this.

A 4 1/2" angle grinder will work fine so long as you take it in a couple of passes, instead of doing it all at once.

The helper with a shop vac plan also works well, but make sure you have a fine filter in the shop vac or you'll just pump the dust back out.

My day job is tile & stone setting, and I cut grout and stone all the time.

Rick.

[Jeff Nolan]

the guys that installed my granite counter tops used a skilsaw (worm drive) with a continuous rim diamond blade. They even used a small hose to dribble water into the cut as they were going... I wouldn't believe it if I hadn't seen it with my own eyes. Probably won't work for you given that it's already installed but if you can control the dust I would definitely go with a skilsaw.

[James Stokes]

The best way I have found to control the dust is get a pressurized pump up garden sprayer. Have your helper in front of you spraying continiously The granite and blade. You will end up with a sludge to clean up but that is much easier than the dust.