How does the layman drill a 2" hole in concrete block?

**Lakee911** · 10-19-2009, 10:10 AM

Subject says it all ... how does the layman (me) drill a 2-1/2" diameter hole through an 8" hollow concrete block wall?

Would a carbide tip hole saw on an extension do the job? Center bit won't be masonary bit....

Thanks,
Jason

**iminaquagmire** · 10-19-2009, 01:43 PM

Diamond core bit if you want the hole nice and clean. Look here for good prices. I've used these and they worked well. Or if you're not particular about the hole, you can drill a bunch of smaller holes in the shape you need and break it out. You're gonna want a hammer drill if you don't use the core bit.

**Lakee911** · 10-19-2009, 02:01 PM

Your link didn't work.

**Ian Gills** · 10-19-2009, 02:04 PM

It's EGay.

**jadnashua** · 10-19-2009, 02:38 PM

If you only needed to do a couple, a concrete block wall shold be able to be drilled with a carbide holesaw. Note, if you hit a rib, it would be a big pain whatever you used. The centerhole bit can probably be found with a carbide tip, or, just drill the hole with one, then, the bit is just a guide. In fact, you could just use the shaft and not dull it at all. Once the hole saw is started, you don't need the center bit but you need to be careful. Diamond core bits often do not have a center bit, and it is an aquired skill to start them and get the hole where you want without it walking all over the place (this would probably work with the hole saw as well). Basically, you start with the drill at about a 45-degree angle so only a little edge is cutting, once it makes a decent divot, you slowly pivot the drill so it is perpendicular to the wall and finish the hole.

hj · 10-19-2009, 02:58 PM

IF the hole is not on a web and the wall is not grouted, a swift blow with a hammer in the center of the hole, and then tapping around the edges will give you the hole you need.

**Lakee911** · 10-19-2009, 03:16 PM

Excellent advice! Thanks. I'll let ya all know how it goes in week or so when I do it.

Edit: Those guys on the e-homo****** site that Ian mentioned are going to set me back at least $30 or so for a one-time use.

So, I'm going to just drill a series of small holes and then tap it out with a hammer. I'll be mounting a 2" LB against the hole, so that will cover most of the "handy work."

The backside is a semi-inaccessible crawl space so I'll probably just use a cold chisel and bust out a chuck.

Thanks,
Jason