# Drilling through foundation



## BBQ (Nov 16, 2010)

If there is no rebar you can dry core through with a large hammer drill, if there is rebar you will want a real core drill.


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## kevmanTA (Jul 20, 2010)

Block wall.. 20 oz. hammer, just keep hitting. I rarely use a drill anymore for holes in block walls.
Poured? Coring bit.


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## woodchuck2 (Sep 18, 2009)

I just rent a core drill. Much cleaner in the end and i pass the expense on to the customer.


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## Mr Rewire (Jan 15, 2011)

I have a dry core bit that will cut for a 2 in PVC I rented one a few times then just bought one. It will bore through almost anything but rebar does slow it down a little.


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## Wiredude (May 14, 2010)

We often use our dry-core bits (up to 5") on a 9" grinder. You just have to feather the trigger. If you just hold it on it spins too fast and gets hot and ruins the bit.


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## Zparme (Nov 11, 2010)

Do you use the dry core bit on hammer mode?


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## Mr Rewire (Jan 15, 2011)

Zparme said:


> Do you use the dry core bit on hammer mode?


 I do :thumbsup:


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## Big John (May 23, 2010)

I've successfully dry-cored through 1/2" rebar in a pinch. But it's a good way to chew up your bit if you do it a lot.

-John


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## Mike_586 (Mar 24, 2009)

Zparme said:


> Do you use the dry core bit on hammer mode?


If we're talking about the bits that are designed to be used with SDS drills then yeah you can use them in hammer mode, though really soft materials cut better without the hammer action.


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## B4T (Feb 10, 2009)

Wiredude said:


> We often use our dry-core bits (up to 5") on a 9" grinder. You just have to feather the trigger. If you just hold it on it spins too fast and gets hot and ruins the bit.


Why would you want to use a core bit that way?? :blink::blink:

How do you put pressure on the bit without wearing out the bearing since you are pushing on a sideways motion..


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## BBQ (Nov 16, 2010)

B4T said:


> Why would you want to use a core bit that way?? :blink::blink:
> 
> How do you put pressure on the bit without wearing out the bearing since you are pushing on a sideways motion..


I have seen GCs do it that way, it works.


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## B4T (Feb 10, 2009)

BBQ said:


> I have seen GCs do it that way, it works.


That is a nice setup.. water feed and speed control..


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## drsparky (Nov 13, 2008)

Isn't dry coring frowned upon by the folks that protect us from ourselves? Seriously inhaling concrete dust is very bad for you.


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## tkb (Jan 21, 2009)

I have the Weka DK13 handheld core drill that can do dry or wet coring.
When using it dry I can hook a vacuum to it and drill dustless.
It sucks through the bit to cool it and remove the dust.

I also have the rig to go with it.

http://www.diamondproducts.com/M-4%20Rig.htm#M-4 Complete Core Rig

This rig has a clutch, not like using a hand grinder with a core bit. That could be a killer.


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## MF Dagger (Dec 24, 2007)

I have a 1" bit, if I need a bigger sized hole, which I rarely do, I just drill a bunch of smaller holes around a hole that I mark out and then use the chisel bit to knock it out.


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## Wirenuting (Sep 12, 2010)

drsparky said:


> Isn't dry coring frowned upon by the folks that protect us from ourselves? Seriously inhaling concrete dust is very bad for you.


Some of the old concrete used Asbestos as a bonding/ hardening agent. 
Burn a bit out real quickly.


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## Wiredude (May 14, 2010)

B4T said:


> Why would you want to use a core bit that way?? :blink::blink:
> 
> How do you put pressure on the bit without wearing out the bearing since you are pushing on a sideways motion..


I don't follow what you're asking really. Dry bits only, and you just use the grinder handle back by the trigger to keep the thing from spinning, you apply pressure on the bit by having a hand on the back of the grinder head, the side-handle really isn't too useful when doing it.

We do have both hand-held and stand core rigs, but often, if you just need one or two holes through hollow block, it's just alot less stuff to carry around if you use the grinder. Plus, with the grinder there's no adapter/reducer to loose, the bits thread right onto the shank of the grinder.

BBQ -- That rig in the video is different, never seen one like that, looks like it was designed for coring, with the water hook-up and everything, unless that's some special add-on kit or something. Pretty slick!


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## Josue (Apr 25, 2010)

BBQ said:


> If there is no rebar you can dry core through with a large hammer drill, if there is rebar you will want a real core drill.


What do you mean?

Which are the "real" ones?


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## Phil DeBlanc (May 29, 2010)

Just call the Vermier salesman and have him demonstrate a horizontal rig for you!


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## nitro71 (Sep 17, 2009)

Can also pay a hole cut company to come knock some holes in for you.


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## Jlarson (Jun 28, 2009)

BBQ said:


> If there is no rebar you can dry core through with a large hammer drill, if there is rebar you will want a real core drill.


That's how I roll, although sometimes I'll use a rebar eater bit in a large hammer drill if its in a place where coring would be a pain.


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## thegoldenboy (Aug 15, 2010)

Josue said:


> What do you mean?
> 
> Which are the "real" ones?


A real core drill is just that, a core drill and not just a core bit on a hammer drill.

http://www.milwaukeetool.com/tools/...e-base-stand-vac-u-rig-kit-and-meter-box/4136


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## Josue (Apr 25, 2010)

thegoldenboy said:


> A real core drill is just that, a core drill and not just a core bit on a hammer drill.
> 
> http://www.milwaukeetool.com/tools/...e-base-stand-vac-u-rig-kit-and-meter-box/4136


OK.

What do you do if you find re-bar when you are core drilling? (hammerdrill)
Will it cut through or do you need a special tool?


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## thegoldenboy (Aug 15, 2010)

Josue said:


> OK.
> 
> What do you do if you find re-bar when you are core drilling? (hammerdrill)
> Will it cut through or do you need a special tool?


The core bit will cut through it but it does take a toll on the bit after a while. I forget what company, maybe Milwaukee, makes a core bit designed just for cutting through re-bar. Drill, hit re-bar, change bit, remove re-bar, change bit, finish hole.


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## nitro71 (Sep 17, 2009)

You don't want to smoke your non-rebar bit on rebar. Bits are way to expensive. I don't have any experience with dry drilling rebar. Would be cool if a company made an attachment for a drill to allow you to pump water into a diamond bit.


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## tkb (Jan 21, 2009)

nitro71 said:


> You don't want to smoke your non-rebar bit on rebar. Bits are way to expensive. I don't have any experience with dry drilling rebar. *Would be cool if a company made an attachment for a drill to allow you to pump water into a diamond bit.*


That is a core drill, not a hammer drill.

Using a "core" bit on a hammer drill is not the same as a true core drill.


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## B4T (Feb 10, 2009)

Is a core bit diamond tipped or do they use something else as a cutting edge..

If it is diamond tipped.. would rebar still dull the bit?


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## nitro71 (Sep 17, 2009)

B4T said:


> Is a core bit diamond tipped or do they use something else as a cutting edge..
> 
> If it is diamond tipped.. would rebar still dull the bit?


Dulls slowly when used in a water cooled application. 10-20 holes and your bit will be shot.


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## tkb (Jan 21, 2009)

Core drill bits are dimand tipped.
Hammer drill core bits are carbide tiped.

Core drill bits are usually water cooled.
Hammer drill bits usually have a center pilot bit attached and are not as deep as a corring bit.

Hammer drill core bit, not so good on rebar











Diamond core drill and bit, will cut through rebar and you won't even realy feel the difference.


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## thegoldenboy (Aug 15, 2010)

My company has a dry core drill, standard diamond tipped core bits but a hammer drill body, except I don't think it has hammer. The manufacturer escapes me at the moment. It's only good up to a certain size and then it's time to break out the regular core drill.


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