From what you have posted you will have a BIG mess if you try to do
this yourself. You have stated that you are trying to cut a finised
moulded cutout in a granite slab for an undermount sink. This means you
will have to cut a very precise hole and then mould the edge of this
hole with a router and then polish that edge. This will be a very
involved process in the field. You can look at routers and bits for this
purpose at places like www.masterwholesale.com. They also sell polishing
kits/pads and abrasives for the subsequent steps. The router bit alone
might cost 400-500 dollars. This process is normally done in a shop with
a CNC router. This is not something you do with a hand held woodworking
router or a grinder.
If I were you and I were really trying to pull this off on my own I
would go for a square edge sink hole. You would need a diamond core bit
to match your needed radius at the sink corners (square/rectangular
sink), a diamond blade, and a polishing set. It will be a LOT of work
and a LOT of mess and will probably result in a substandard result as
compared to a shop doing it but that may be acceptable to you. You could
punch holes at each corner with the core bit, cut to those holes with a
diamond blade, then polish a day or two. The end result could be
anything from a disaster to somewhat acceptable.
If the hole needs to be oval, round, or must have a routed edge, I would
not even consider doing it.
I would say you will still be looking at quite a chore. The only
experience I have with the process is having had to cut unfinished edges
on a few granite counter tops and the occasional faucet/sprayer hole. I
have done a bit of concrete polishing as well.
Like I said before. Perhaps going with a bit more simple shape (square
edge, eased) you could perhaps make something work. You have to realize
that you will have vast amounts of water (read hundreds of gallons) and
the associated slurry to deal with. This grinding and polishing is
normally done on a fabricating table which collects this water and
slurry to a settling tank for reuse. You could perhaps build a quick
grinding table out of ply lined with poly and a shower drain in one end
run to a few 55 gallon drums. Pump out of the drums to grind/polish and
let them settle out overnight. Set your slabs up on a couple blocks
inside the table.
With high quality smooth diamond blades on your saw, a good guide, and
water, you could perhaps come out with smoother rough cuts minimizing
polishing. Square edges eased would eliminate the need for the routing
step. Its a major undertaking but your posts sound like you are determined.
A good trial, and probably the cheapest, would be to go to a granite
supplier and ask them if you could buy a few of their scabs (broken
corners, scraps, and so on). Take them home and get started. You will
have to invest in the equipment for the tests but at least you wont be
out the time on the actual pieces and the material if you find its too
Finding an affordable saw that will allow you to wet cut without getting
fried may be a tough one. I have seen small trim saw sized hand held
cutters with water feeds for sale at the home centers however with the
amount of cutting you will have I would suggest buying them by the dozen
and a lot of blades. Perhaps a decent but cheap double insulated
circular saw and rig up your own water feed. Buy a pair of insulating
rubber gloves and work of a GFI. The GFI will probably trip continuously
but you at least wont get fried. Cutting the slabs dry will result in a
tremendous amount of grinding and polishing.
Good or bad it would be interesting to hear your results,
Thank you very much for your comments. I was thinking that I could cut the
granite dry and then grind the rounded surfaces before polishing. That's
what the granite tool supply shop told me i could do. They should know what
they are talking about but you never know. Since you are interested, I will
keep the group posted. Probably wont' start this project for a couple more
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