Diamond drill bits

[zepper]

Hey guys – I'm installing a quartz countertop for our bathroom vanity. I had the countertop made and the openings cut (the sink opening, according to its template).

I must now drill 4 holes in the counter's underside for the brackets that came with our ceramic undermount sink. I'll then epoxy the threaded bracket anchors into the holes, and use 100% silicone between the sink and counter—sound right?

I've done lots of drilling, including some in masonry, but never this particular kind. I understand I must use a diamond bit, and must keep it water-cooled. BTW, this installer uses plumber's putty to contain the water around the drill areas:


My question is: What type of diamond bit should I use? Some look like conventional high-speed bits:

...and some are cylindrical:

But most of the ones I see are tubular:

Which is best for this? A tubular bit seems like it'd start the hole the easiest—but wouldn't it just cut a ring in the material, rather than a hole? Maybe I don't get how they work.

You may be tempted to suggest I hire specialists instead. However, I've taken on other complex jobs, and found that with the right tools, and enough education, patience and care, I've been able to pull them off surprisingly well. So unless you think I'm an absolute fool to attempt it, I'd like a chance to do this too. I plan to drill slowly and carefully to avoid damaging the counter or myself. (Fortunately it's 3 cm, so less likely to crack, I figure.)

Thanks for your time and input!

 

[zepper]

Just to be complete here, I also see bits that are a combination of solid and tubular:

 

[zepper]

Finally, I see some people also use these epoxy-on brackets that don't require drilling:

Of course they wouldn't be as strong as anchors cemented into holes—but are they strong enough? (Ours is a single sink, BTW, not a double.) Thanks again!

 

[zepper]

And sorry, BTW... When I wrote that first post, I'd had coffee and babbled much more than necessary. I can't find a way to edit it, though. Are we really not allowed to edit our own posts here? That'd be a first—and I've been on message forums since someone thought them up.

 

[Steve123]

Post removed.
I thought you were drilling holes for the faucet.

 

[Snoonyb]

Silicone works best 20' deep in a landfill, unopened.

I've used both diamond bits and epoxy, with about equal results. I've never had faith in the diamond coated bits, as anything more than an expensive abrasive.

 

[bud16415]

I like the glue on idea.

 

[zepper]

Thanks, guys. Turns out the ring-type drill is for cutting holes straight through (duh).

Since I'm drilling only 1.5 cm into my 3 cm counter, I picked up one of the speed-bit type. Will put tape on bit at proper depth, naturally. Cheers!

 

[mabloodhound]

good luck and let us know how it goes.