Drilling a granite surface plate

Relton makes a series of carbide-tipped masonry drills called Groo-V "GRT" series. They are capable of drilling granite. You should be able to do it using a drill press, mill, or even a hand drill if you can stand to press on it for that long. They're not too expensive either.

Regards,

Robin

I would be disinclined to use a carbide drill fror this application and would lean towards diamond grit hole saw and plenty of soapy water.

Have it core drilled. Look in the yellow pages under "Concrete Drilling" and find somebody who has a water cooled diamond core drill. If you take it to them, it should be reasonable. I have 2" holes, 6" or 8" deep, drilled in concrete from time to time for setting railings, and the going rate is about $50 a hole- that is including having them drive to the job site, and set up and drill em there. I would guess if you take it to them, and paid cash, 25 bucks would probably get it done.

And any carbide or diamond bit you buy is gonna cost that much, plus it being your first time and all, you run a pretty fair risk of chipping or cracking the plate- whereas these guys do it all day every day, with thousands of dollars worth of machine, and can make it look easy.

Core drilling for a 1/2" dia hole???

Google for diamond tipped core drills. Use wet, with a flood of plain tap water. This can be done on an ordinary drill press, if you wipe it down afterwards, to prevent excessive rust.

Joe Gwinn

I've got a diamond bit, 3/4" I believe, that I've drilled through countertops with. It has a 5/8-13 mount, same as 4.5" grinders do, but it takes about 3000rpm to be effective, so you need a variable speed grinder. I made an adapter and used it with a drill, but it's very slow at that speed. Has to be used wet, best to dribble water on it if you don't have a more sophisticated water supply setup. These bits can be purchased online for about $60, IIRC. 4" is pretty thick, it would take some patience.

Please think about high pressure water-jet, it could cut the hole without any damage. They used to mix the sands into the water, it may grind the surface well.

Call a counter top group - simple as that. Caution them on the surface and protect it with cardboard to keep them off it.... Maybe all will go well.

Otherwise a water cooled core drill.

Martin

Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net TSRA, Life; NRA LOH & Endowment Member, Golden Eagle, Patriot"s Medal. NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member.

snipped-for-privacy@yahoo.com wrote:

Chuck up a pc of copper tube in a drill (strengthen chuck end with 2" pc of rod in tube to prevent collapsing.)--drill several cross holes for water circulation. 2" working length sufficient to start.

make a putty dam around the hole area to contain coolant. or build channel to edge & catch in bucket.

Use medium grit silicon carbide abrasive slurry--drill a few seconds, lift drill add a little abrasive, drill again, .

there is an optimum amount to add to keep from wearing out the tube before drilling the hole.

after drilling an inch or two, you can break off the granite core.

Don't go so far with the first drill that your hole goes too far undersize that a new bit won't go in it.

Have Fun

Did you try a plate glass shop??

I have tried to think granite but find it hard to do.

Try a monument shop...as in headstone/gravemarkers.

Mike

I have core drilled glass using Jerry's method and it works well. I used a slow speed (250 rpm, 2" hole) and #120 SC. You can set it up in a drill press and hang a 5-10 lb weight on the drive bar to apply continuous pressure, and then just keep adding a bit of SiC and water. If you cut 1/4" slots in the end of your copper tube with a hacksaw, it improves grit circulation and speeds it up. Finer grit will give you a smoother finish.

Scott

Bingo... Except soap is not needed and plenty is an understatement.