Mondays Random Question . . . How do you cut Granite Slab ?

[Roadkill]

It's all a bit at the moment but I need to know If I can cut a 35mm thick granite slab (worktop) with a electric / pertrol angle grinder fitted with a diamond edged disc ?

If you need special gear the idea's out but if it's do-able . . . . . . . . . .

[ianjpage]

Well from what i can find on the internet you just need a diamon blade and it must be wet cut....

[Titsy]

it's normally cut by mashine on a slow feed with a constant coolant feed...

[Roadkill]

Quoting: ianjpage

wet cut....

Quoting: Titsy

constant coolant feed...

Hmm, petrol, then . . . with a bowser.

[Titsy]

Quoting: Roadkill

Hmm, petrol, then . . . with a bowser.

are you sure the alton towers fire was nothing to do with you???

[Roadkill]

Quoting: Titsy

are you sure the alton towers fire was nothing to do with you???

I HAVE WITNESSES !!!

[Big Mouse]

As long as you take your time, hold the cutter dead steady (it will chip real quick and maybe even bite back at you if you don't), take your time and keep a constant supply of cooling agent flowing into the blade/cut area then you should be fine - it won't be pretty but it will do the job, the finished edge will be pants but as long as you don't want to look at it you'll be ok.

Blade needs to be at least 5 times the thickness of the material if I remember correctly 35mm = to at least a 175mm diamond blade - the price alone of a diamond blade may put you off!!

I'd seriously consider taking it to a local company that cuts stuff like that

[55starchief]

Everytime i have seen it cut its usualy on a feckin big machine with a 24" blade, have also seen it water cut

[art b]

when i cut masonary stuff i have someone keep it wet with a garden sprayer,stops the dust and cools the blade

[Roadkill]

Quoting: Big Mouse

Blade needs to be at least 5 times the thickness of the material

Is that blade diameter or the radius ?

Quoting: Big Mouse

the finished edge will be pants

That's fine . . . it would be an "end" and would butt-up to a wall (and be sealed-in).

Quoting: Big Mouse

I'd seriously consider taking it to a local company that cuts stuff like that

I'll have a phone round when the time comes . . . I've cut pretty much everything else (steel, ally, concrete, brick, slab, stone . . . ) so aren't a complete noob.

That said I appreciate that granite is like the titanium of stone so will certainly take your advice on board.

Cheers for the input.

[Roadkill]

Quoting: art b

when i cut masonary stuff i have someone keep it wet with a garden sprayer

If making verticle cuts another trick is to hang a soaked towel behind the object/wall which you're cutting.

Works wonders at keeping dust down.

[55starchief]

Quoting: art b

when i cut masonary stuff i have someone keep it wet with a garden sprayer,stops the dust and cools the blade

Most petrol cutters have a fitment for a garden hose, have you guys seen those blade type ones that cut with vibration looks like some kind of petrol powered martial arts weapon

[art b]

Quoting: 55starchief

vibration looks like some kind of petrol powered martial aid weapon

[F Body]

OK so it's 35mm thick but how wide is the slab ?

Your going to struggle keeping the cut clean and at a right angle with a hand held grinder, one slip could bugger the surface.
Looks like a job for a Professional to me, if you found the right company it probably wouldn't be that costly, although transport could be a problem

[philoldsmobile]

there is a water flo jet company in wellingborough called obec that could probably do it..

[55starchief]

Usualy the place you bu the granite from will cut it to size

[Roadkill]

Quoting: F Body

OK so it's 35mm thick but how wide is the slab ?

I need to trim about 150mm off the edge . . .

Quoting: F Body

Your going to struggle keeping the cut clean and at a right angle with a hand held grinder

As long as it's within 6mm (a heavy bead of silicone) it'll be fine.

Quoting: F Body

one slip could bugger the surface.

True, but it'd potentially be costing me nothing in the first place, so . . .

[Roadkill]

Info dump from DIYnot .com :

Thought I'd post my personal experience here. Firstly we were fitting a Granite kitchen which we had gotten from some very generous friends. Granite was therefore not a choice as such, the problem was how to cut and fit it… especially as it was already bonded to the units. It was also not any of this so-called cheap resin-bonded granite.

I needed to cut several edges and corners, plus add a drop-in sink and a 35mm hole for a tap.

Cutting straight cuts:
I used a DeWalt angle grinder and #3 DeWalt dry diamond disk - It goes though it like butter. Lots of noise and dust! - So wear mask, goggles and ear-defenders;
Take lots of care measuring and lots of care in keeping the cut straight, though the disk itself will want to cut straight anyway because of its shape.

Bevelling/Polishing edges;
I used a set of dry diamond polishing pads, these varied from grade-50 to grade-3000. Dead easy, the pads are Velcro backed with diamond embedded rubber compound… they seem a little dead at first but once the rubber wears to expose the diamonds you're off and running.

Cutting 35mm tap-hole
I used a 35mm diamond core drill, a standard mains drill and a cheap B&Q drill stand clamped to the Granite… a gradual dribble of water stopped the drill bit burning up and once again a piece of cake. Without the Drill stand I had a real battle keeping the drill still on the granite. Perhaps a 35mm guide hole trough some plywood might have worked but for 20 quid the drill stand made sense.

Cutting drop-in Sink
I used the angle-grinder and dry diamond disk again for the straight lines, and the core-drill for the corners…. I elected for a square, rather than a round sink, partly on the basis that the cutting would be easier.

Just plan properly, measure carefully and test out your tools and techniques before cutting the real thing. It's a hell of a lot easier than most people would have you believe…. And don't fall for any of that expensive drilling rig and cutting machine waffle that the tool sire shops would like to rent!

All in all, the approximate cost:
DeWalt Angle-Grinder - £40 from eBay
DeWalt #3 Dry Diamond disk - £18 from eBay
Diamond polishing pads - £20 from eBay
35mm Diamond Core Drill - £10 from eBay
Drill Stand - £20 from B&Q