View Full Version : Concrete Core Drill - Hollow out?

Russ Filtz
02-27-2018, 4:16 PM
OK, trying to make a 2" diam. pocket, 4" deep, in the some thick concrete for a railing post. Going to use a 2" diamond core drill, but then how to hollow out the rest? My initial thought was to then drill out the center with a 1" or smaller bit, as I was going to drill all the way through the slab for a drain hole (the railing is only used intermittently). Then either keep drilling with even smaller bits and/or start chipping away with a cold chisel.

Can't seem to find a solid 2" diam. milling/grinding bit. Any other tricks?

Adam Herman
02-27-2018, 5:30 PM
should be able to whack it with a hammer and bust the core out.

Matt Day
02-27-2018, 7:41 PM
A 2 but is pretty small, so a cold chisel in the kerf and a hammer will snap the plug loose. Drill the drain hole from there.

Mike Cutler
02-27-2018, 7:46 PM

Look under 2" rotary hammer drill bit and you should find some choices.
They're not cheap though. Amazon has a DeWalt for ~$150.00 and Home Depot has some Bosch for $160-$175. It was just a quick look though.

Ken Fitzgerald
02-27-2018, 8:08 PM
Check with a local rental company.

Bruce Wrenn
02-27-2018, 8:52 PM
Once I got 2" hole bored, before breaking loose, I would drill a small hole 1/4-3/8" in center and insert an sleeve anchor, with a short piece of chain attached. After you break core loose, chain will allow you to pull core. When you pour hydraulic cement around post, leave it down about 3/4" below surface. Then make a "neat" mortar collar that extends up above the concrete to prevent pocketing of water. Been there, and done it, and got paid handsomely. Did a complete set of stair rails two stories high, all of which rusted off at top of pocket, as they had standing water in pockets where hydraulic cement settled. Rails were from a swimming pool. Chlorine in water, dripping from hands caused to to rust faster. Rent both bit and drill.

Mark Bolton
02-27-2018, 9:17 PM
Weve drilled small and large cores deeper than any core drill can reach. The chisel hammer works but often times just a screw driver or pry bar will pop the core loose to lift it out with your fingers. For deep holes a tapered drift pecked in the kerf willl pop the core loose. Run the core drill down and it will likely carry the plug back out with it.

Don't over think it.

Russ Filtz
02-28-2018, 6:06 PM
Thanks all, will try some of the proposed options!