# drill 2.5" hole through 10" concrete hole



## Ron6519 (Mar 28, 2007)

diy001 said:


> I want to drill a 2.5" hole through a 10" internal concrete wall for my 2" washer drain.
> 
> I did some research. I think I need this core drill bit: SDS Carbide Masonry/Concrete Core Drill Bit 2.5" x 6".
> 
> ...


Where does this pipe go when you drill the hole? Cesspool? Sewer connection?
Ron


----------



## diy001 (Sep 25, 2009)

Ron6519 said:


> Where does this pipe go when you drill the hole? Cesspool? Sewer connection?
> Ron


it will connect to a 3" Sewer pipe.


----------



## Daniel Holzman (Mar 10, 2009)

I drilled a 2-1/2" diameter hole through my 10" concrete wall for a sump pump connection. I rented an electric Bosch rotary hammer (I do not remember the model number) with a 2-1/2 diamond coring bit. The process was relatively slow, but quite effective. The stand was critical, the tool I used had enourmous torque, enough to take your arm out of the socket if you tried to hold it by hand. The bit also had a habit of catching if it was not held exactly perpendicular to the wall, then the drill would start to rotate the stand. I had to be very careful about that, it happened several times.

I know there are several manufacturers of rotary hammers, I can't comment on which ones are better. I can say that I filled the space surrounding the pipe with expanding foam, and sealed the face with about a 1/2 inch of hydraulic cement. This has worked well for many years now.


----------



## I know nothing (Jan 17, 2016)

Your links don't seem to work. But, I too would recommend the 2-1/2 diamond coring bit, and they can drill straight thru from one side. BUT, they do have some torque, and if they hang, they will twist your wrist and/or arm. That said, can you get to the other side of the wall? if you use the standard auger hammer drill bit and drill from one side only, you will 'blow out' a rather large chunk on the opposing side. try running a 1/4" pilot bit all the way thru so you can find and drill 1/2 from both sides.


----------



## Mingledtrash (Nov 27, 2015)

Daniel Holzman said:


> I drilled a 2-1/2" diameter hole through my 10" concrete wall for a sump pump connection. I rented an electric Bosch rotary hammer (I do not remember the model number) with a 2-1/2 diamond coring bit. The process was relatively slow, but quite effective. The stand was critical, the tool I used had enourmous torque, enough to take your arm out of the socket if you tried to hold it by hand. The bit also had a habit of catching if it was not held exactly perpendicular to the wall, then the drill would start to rotate the stand. I had to be very careful about that, it happened several times.
> 
> I know there are several manufacturers of rotary hammers, I can't comment on which ones are better. I can say that I filled the space surrounding the pipe with expanding foam, and sealed the face with about a 1/2 inch of hydraulic cement. This has worked well for many years now.


Bosh and hilti are the leaders in rotary hammers.

This is for sure a rental situation 2 1/2 bit will prob never get used again if you buy it. 

You can rent a core drill at most big equipment rental businesses. like hurtz or united. if you want to buy one they run around $2,500. If you insist on drilling this size of core without a rig you might as well calculate a broken arm into the cost.


----------



## Wildbill7145 (Sep 26, 2014)

Mingledtrash said:


> Bosh and hilti are the leaders in rotary hammers.
> 
> This is for sure a rental situation 2 1/2 bit will prob never get used again if you buy it.
> 
> You can rent a core drill at most big equipment rental businesses. like hurtz or united. if you want to buy one they run around $2,500. If you insist on drilling this size of core without a rig you might as well calculate a broken arm into the cost.


Bingo. A friend of mine and I did concrete coring in highrises for a few years with the Milwaukee version of this tool. I'd have to imagine doing what your planning with anything else will take you absolutely forever and yes you'll want new arms afterwards.

You will still need a hammer drill to punch the 4 holes for the hilti shots to bolt this thing down. You'll also need a water source to keep the bit cool. I'd also add, don't forget the brass washer that goes between the drill and the bit when you're attaching it. Otherwise once used, you'll never get that bit off the machine. Don't ask how I know that. I was just the stupid helper.


----------



## I know nothing (Jan 17, 2016)

*Core*

Yes, the Boss has steam coming out his nose and ears when he finds out :vs_mad:that others, :vs_worry: , had not put the washer between the shaft and the bit. Nearly impossible to remove the bit. And, know one ever mentions that until the drill is sent to the next job.


----------

