Cutting granite bench tops

Hello all,
I am between a rock and a hard place. I have a reno underway which includes granite bench tops. No local stone cutter exists and the nearest available is 2 1/2 hours away @ $180 / hr.:( No wonder he is :D
The owner is keen to have either me or him have a go but builders are not stone masons and only extreme need has bought me to consider it. On new work its just another inclusion and not an issue but this kitchen is new auction stock which I have to make fit.
Advice from anyone who has fitted granite would be much appreciated, unless I feel confidant I will duck this one. Regards from Bill

are you using "real" stone or an enginered stone.

Real stone, not synthetic or composite. Probably Chinese or Indian. Black & hard.

maybe get the front edges factory cut and polished, then just trim the back to suit your wall. diamond disk in grinder would be worth a shoot but very messy unless you wet it down. you will have it take it slow whe cutting..
3

Fronts are bullnosed, problem areas are two joins on each change of angle and the sink. Sink s/b ok but jointing worries me. Any suggestions, apart from leave it alone?

When they put in my granite benchtops they cut out the sink & stove openings with angle grinders using diamond cutting wheels . they also beveled the edges the same way . This was 20mm thick stuff.
Mind you these blokes did this for a living they came from gosford so no help there i'm afraid
But if you could get a 5" grinder or larger, a diamond wheel and practice on a spare bit, it wasn't that hard they lent me their grinded and i cut one of the offcuts up for a couple of breadboads to match the bench top SHMBO was very pleased
Not sure of the quality of the diamond wheel however proberly pretty expensive from the cost of the granite and fitting they could afford the best.



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Originally Posted by gnu52

I have a reno underway which includes granite bench tops. No local stone cutter exists and the nearest available is 2 1/2 hours away @ $180 / hr.

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Paying $900 for the stone mason to travel to you is maybe not such a bad deal. If you're flexible on when you want him to come you could possibilly talk him down to $500 and a night's accomodation.

If you want to do this yourself the tools I suggest you need are either:
an angle grinder with a diamond blade -- very very messy, and it's difficult to hold a straight line unless you've had lots of practice. or
a dustless cutter (Makita make one) connected to a good dust extractor. The Makita dustless cutter is like a portable power saw and can be guided by a battern making straight cuts pretty easy. The dust extractor works and is essential if you want to keep the owner's house clean. The tool is also very handy for cutting cement sheet.

But the big cost is smoothing the exposed edges arround the cut outs and on the edges that but against walls. What needs to be done is akin to sanding the saw marks out of a piece of timber. However with granite you need to use diamond polishing disks to do it and these are not cheap. The guys who installed the granite counter top in my kitchen used an angle grinder style polisher and commented that the polishing disks cost $800 each. Very Ouch for a one off job.

Bill,
if it was my own kitchen I'd probably give it a go, but as it's for a client I'd be getting the specialist in. I've seen them cut on site with a diamond blade in an angle grinder for the cutouts. For cuts to areas that will be seen, a Festo plunge circular saw on a guide rail and the matching dust extractor. Edges polished with stones of varying grit in a 7" sander/polisher. Have to work on getting all the carcasses really level. Tops are glued down with a specialist epoxy - very thick and with grit in it.

Mick

Bill,

Granite dust is very bad for the lungs, if you are into inhaling large amounts of MDF dust this is just as bad over time and it is not advisable to add it to what ever nasties you may have breathed in. Although granite is very tough, and your black could easily be Irish or European as well as Australian, it is also brittle if there is a flaw running through it and the black makes it difficult to spot the flaws. As alluded to the gear for polishing and cutting is expensive and as it is a contract job I would be very reluctant to give it a go, if you crack the slab or stuff the joint the stone mason suddenly does not look so bad after all. Your basic diamond gear will eventually cut it but any flushing along the joins will show as a very clear light grey.

JohnC

Bill
you may want to browse through Hoskin Diamond Products at
http://www.hoskindiamond.com.au/index.htm

a tip, watch the areas around your cutouts. i.e sink and hotplate.

make sure the cabinet carcase has a good size rail on the vertical to support the stone or these areas will be prone to cracking.

if it were me, i would make a set of 3mm ply/mdf templates with the exact detail, scribed to the walls and get the professional to do the joins in his factory. the attempt to do the cutouts myself onsite with a grinder and diamond blade as these dont need to be pretty.

G

could you mark the cuts you need and take it to the stonemason yourself? It would save the hassle of doing it yourself and would be cheaper than getting him to come to you.

Trav

Thanks to you all for your imput which I am now chewing over.
Probably we will take the granite to Brisbane & have it professionally cut from templates of 5mm craftwood.
The mason tells me even if he does the cutting in his workshop I will still have to cut out the sink on site as they are prone to cracking in transport. I see his point.
Again, thanks from Bill

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if it was my own kitchen I'd probably give it a go, but as it's for a client I'd be getting the specialist in.

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Bill

Listen to Mick's advice. The owner is trying to save a buck at your expense. Who is responsible for replacing the material if you stuff up? Let the owner pay someone who can do the work (it is a relatively small amount in the grand scheme of things), rather than you stressing over something that you are not qualified to do.

Regards from Perth

Derek

Well I must say I'm pretty dissapointed! I saw that the dark master had replied to this thread and thought I'd better check it out. I was expecting detailed instructions on how to cut and polish granite with traditional handtools :eek: . It would probably only take a few weeks with the right tools. ;)

Mick

Mick,It's score and snap, just like glass, only you use a tungsten tip chisel but for a real traditionalist the hand forged tempered steel edge is the go. Then just smooth with the chisel or patent axe very fine taps no cut and bash here. All you blokes have probably got the rest of the gear, start rubbing back with carborundum getting down from harsh to finer grades and then finish off with your finest waterstones. And there is your answer as to why Derek probably is not interested afterwards if doing a large area they will be flat if an edge then they will look very average indeed.

I think I know why a power cord has the edge over the old way.

JohnC

John,
I was hoping we could start from scratch, you know driving wooden wedges in cracks and then wetting them in order to expand them and split off a slab. Or I believe that they used fire to split off slabs also. Then flatten and polish by hand and none of this new fangled carborundum or tungsten either ;) .

Mick the traditionalist
(traditional power tools that is! :p )

Mick,

I don't know about fire that's a new one to me, the traditional method is with hammer and drill, the drill resembling a chisel with a slight curve and wider at the pointy end than the shaft. You drill about 6" into the stone with the holes about 6" apart running in the line you want to split then fill with water and wait to freeze overnight nature does the hard work. When the weather is to warm you pop a couple of tapered pieces of metal in and a pin in the centre and belt these these things into the waiting holes until it splits. Good stone has a grain like timber, although the advent of the diamond saw means this is not so important these days.

To get the reference edge you use a tool similar to a very blunt bolster to strike a straight line then use a chisel to run a reference edge on the face you wish to polish.

To get a flat surface work it back with a punch, move to an axe, then a chisel, then a patent axe, then various grades of stone to rub back to a polish. Most people reading this wouldn't have a clue what half these tools are but if I ever get out of the stone age and buy a digital camera I'll post a few pics.

How about that and no mention of carborundum anywhere.

I've done the drilling and rough work but have never had a go at polishing granite it's to damn hard, but marble is relatively easy.

JohnC.