Cutting Hole in Stone Flag...

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.

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.

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.

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

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

Ta,

Alex.

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

Ta,

Alex.

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

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.

Now there's an idea!

Alex.

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

Or use a square grate?

Christian.

Grate is inside gully. Gully round.

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

Alex.

doncha just love usenet :-)

RT

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.

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.

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...

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.

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

Ta,

Alex.

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.