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I am building a brick wall from concrete blocks. Note that these concrete blocks just provide a facade, don't hold any weight except an additional layer of same bricks above them.

The blocks are 4" high, I want to run a 2" pipe through the middle. The 2" PVC pipe should fit snugly. Is there any certain kind of drill/bit I should add to my electric drill to do this work?

I have a very cheap corded power drill and a battery-powered one as well.

Is there a certain kind of drill bit I should add to my electric drill to do this work?

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Alaska Man
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Village
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4 Answers4

11

To make a clean, precise hole in concrete, use a diamond core bit. Your small, cheap drill probably does not have sufficient torque and runs too fast for a core bit this large. But you can rent a heavy duty drill and core bit.

Wikimedia Image enter image description here

MTA
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5

MTA gave the right answer about the bit. Make sure you get diamond (see his answer for what it looks like) and not tungsten carbide (pictured below).

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Also make sure the bit fits on the drill, and check you have the correct adapter before leaving the shop!

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Professional diamond core bits use a special screw mount to the special huge and powerful drill that is used to spin them. For 2" hole you don't need to pay extra to get that. You can spin them with a drill, but it needs torque, so it has to be a drill with a gearbox. If you use your typical hammer drill, it will spin very fast, which will be dangerous, and it won't have torque at low speed.

I use a rotary hammer drill for this, in first gear, with the hammer action set to OFF obviously! It turns nice and slow, with good torque. You need to stick a big sponge full of water inside the bit, so it gets squeezed and the water released as it bites into the material.

In fact, since you will need to make a center hole with a drill first, I'd recommend renting (or purchasing) a SDS rotary hammer drill. Then either get a diamond core bit with a SDS adapter (picture above) or a hex adapter, but your drill will need a hex chuck on top of the SDS chuck.

If the diamond bit does not have a center alignment bar poking out of it, clamp some pieces of wood on the workpiece to make a guide. You can make a triangle with 3 pieces of wood, that will hold the diamond bit cylinder in place while starting the hole.

bobflux
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MTA's answer is the best plan if you care what it looks like. If the hole will be covered, a series of 1/4" or 3/8" holes drilled with a common masonry bit in a ring will allow you to punch out the center. All the holes in the ring should be outside a 2" circle to minimize the amount of cleanup you have to do after knocking the center out.

You wouldn't want to do this in large-aggregate concrete or stone, but these pavers are soft enough that for one hole you can make it happen. Keep your bit cool or you'll melt it. Dunk it in water every few seconds, before it gets raging hot.

isherwood
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If you are building a retaining wall you may be able to run the pipe under the bottom or around the edge vice drilling through (you do need to ensure your drainage pipe has a slope). I'd also look into the 4" perforated pipe + sleeve vice 2" PVC

jonathan
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