Drilling through concrete

[mr_skittle]

The outdoor faucet at my house sprung a leak over the winter and I'm trying to replace it with an anti-siphon one. The problem is that the long stem on the new spigot is bigger around than the hole. My question is how to enlarge the hole. Do I need a hammer drill with a big-butt bit to ream out the hole? Can I just use a 3/8 in drill and a big concrete drill bit to get the last 1/4 of circumference? I've borrowed a hammer drill but don't want to fudge out the cash for a bit to use once.

[jlanciani]

Rotary hammers and bits are standard fare at rental shops. Renting the right tool and doing the job with ease is a much better alternative than winging it with the wrong stuff when it comes to concrete work.

[Robert Adams]

If its soft then one way it to use a masonry hole saw. Keep the bit wet and they work pretty well even the cheap ones. An sds drill with matching bit will also work if you have it but the holesaw method is cheaper.

   The other method is a chisel and hammer. Btdt and it works and cheap but slow and tiring.

[AUswimKC]

harbor freight

[Lynden]

How thick is the wall? What is the diameter of the existing hole and what diameter do you need?

[crokett™]

With an existing hole, a twist concrete bit will do better and be easier to use than a core box bit (looks like a hole saw). You need a hole thats ~1 1/4" diameter. If you're drilling through brick or block, a 3/8" drill and big concrete bit should work, if you can find one large enough. Most concrete bits I've seen that large are SDS or need a 1/2" drill. If its through solid concrete, rent a bit and use the hammer drill.

[PedroOhare]

Rent an SDS hammer drill. It will probably take 5 minutes with a decent bit and you will be done.

Pedro

[Roly]

If the diameter of the bit is too close to the size of the hole the bit will stick in the concrete and try to twist you.   A flat chisel bit on hammer only mode may work better.    Roly

[Cooler]

I would use a cold chisel and a hammer.  I would think it would take less time than running to the rental place and returning the hammer drill.  (Assuming it is just one hole to enlarge.)

[Phil Thien]

I have not tried this, just an idea:

(1) Rent a concrete hole saw of the correct size.

(2) Cut a plywood donut with an OD matching your existing hole, and an ID matching the pilot of your rented hole saw.

(3) Use the plywood disk as a pilot to keep the hole saw centered when you saw your new, larger hole.