Cutting Hole in Stone Flag...

Need to cut a round hole in some indian stone paving to house a gully grate (approx 10" hole required).

I was thinking of doing it in 2 halves and first slicing at 1" spacing from the edge to the perimiter (4.5" grinder) and then slicing at right angles to remove the bulk, then nibbling from the inside of the semi-circle and cleaning up with a sharp chisel and/or bolster.

But has anyone got a better way of doing this?

TIA,

Alex.

Reply to
AlexW
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Is it possible to find an oversize core drill for hire somewhere?

Finding something over 150mm might not be easy, however, and even if found will be more expensive than the grinder solution.

Christian.

Reply to
Christian McArdle

Maybe you could use a smaller core drill to drill several overlapping holes - but don't drill quite through so you have some support for the pilot drill.

Reply to
Mike Harrison

The problem is that this negates the main advantage of the method, which is to make a nice smooth hole. Using several holes results in the hole still needing tidying up afterwards.

Christian.

Reply to
Christian McArdle

I wonder what happens if you take a carbide woodworking bit in a router, and start cutting.

Reply to
Ian Stirling

I thought about core drills and etc, but have never seen one that big & specialist means expensive, I'd guess.

Ta,

Alex.

Reply to
AlexW

Novel. But guess it might go through a few bits (and routers too)!

Ta,

Alex.

Reply to
AlexW

Hi Alex

Don't! Leave a square aperture for the gully grate and infill with decorative gravel/slate chippings, pretending all along that it's an artistic touch. Add a few more spots of gravel/slate and claim they are decorative highlights.

Dave

Reply to
David Lang

However this might (err not) work.

Making the paving stone rotate, around the centre of the desired hole (centered 'pivot' hole) with a fixed drill (SDS pedestals ... do they exist?) with the core drill set away from the centre at the desired radius. Index the stone round to remove most of the material with full holes and then offset and index again for the remainder and so on until an acceptable profile is cut?

Sounds complicated though, and I am not sure how a core drill would fair when cutting the remainders after the full holes are cut. And could I get all this stable enough etc?

Alex.

Reply to
AlexW

Now there's an idea!

Alex.

Reply to
AlexW

that's the best idea and the most simple (kiss)

you could also cut the square hole, infill with mortar and press decorative glass beads / slate / pebbles / whatever floats your boat into the almost set mortar to avoid having to sweep gravel back into the gap at regular intervals.

RT

Reply to
news

Or use a square grate?

Christian.

Reply to
Christian McArdle

Grate is inside gully. Gully round.

Suppose I could dig up and replace gully put in by the conservatory company though.

Alex.

Reply to
AlexW

doncha just love usenet :-)

RT

Reply to
news

I'd have thought that scoring it on both sides with the grinder then whacking it in the middle would stand a fair chance of working, but I might not try it if I didn't have any spare stone.

Reply to
Rob Morley

We hired a man and machine to drill 12-inch holes in the (private) concrete pavement outside our house - for bollards. I don't remember how much it was, but not a lot. This was a seriously heavy-duty machine, with built-in trolley. I was happy to leave the job to an expert. Try Yellow Pages? In this case you could presumably save money by taking the job to them - not an option for our job.

Reply to
Mike Barnes

Only thing that seems to touch it is a diamnd blade in an angle grinder.

Now I've made holes - semi circular - in slate using a tile saw.

You simply remove MOST of the material and use the edge of the disk to blend it all to shape.

Should work with the angle grinder to...

Reply to
The Natural Philosopher

Got a cut feeling this aint going to work from previous failed attempts at doing profiles the same way a couple of years ago. But its /is/ worth a go as the stone whilst not cheap aint all that pricey.

I suppose I could try and segment the centre with a grinder too and knock through in small segments.

Ta,

Alex.

Reply to
AlexW

Will bear the blending biz in mind, probably use ordinary disk for that bit?

Ta,

Alex.

Reply to
AlexW

That's what I meant - basically a cartwheel design, and maybe drill/chisel through the "hub" first. Be careful how you support it before you started bashing, too - maybe worth cutting a circle in a bit of scrap board to suport it right at the edge of the cutout, you could even bed it in a bit of mortar.

Reply to
Rob Morley

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