# Coring Drills, advice?



## markb (Jun 11, 2009)

Looks like I'm spending a few nights this week coring 30 holes for a floor in an office building here in downtown. The renovations are being done one floor at a time, from the top down. New bathrooms, new stacks etc etc etc. The floor I'm coring has lawyers offices and advertising agencies below the two washrooms and kitchens. 

Obviously we are going to tarp up everything we can, but I'm becoming really nervous regarding the dirty water splashing all over the offices downstairs. I was thinking of drilling a small pilot hole through the slab first, then my helper can hold the bucket directly underneath. Hopefully he catches all of the concrete and water that will fall. 

The only problem I foresee is that the water used to keep the bit cool will just flow through the slab and into the bucket. How much damage is done to a bit when coring holes that are pretty dry? I've always used gallons of water when coring, just to be safe. Anyone have any other suggestions? 

All in all, I'm really excited about my new 5" Hilti bit  Can't wait to give it a go.


----------



## 422 plumber (Jul 31, 2008)

Whenever we cored, an apprentice stood on a ladder with a bucket. Everything was tarped, with towels or blankets laid down. You don't need a lot of water to core a hole, so a 5 gallon bucket would be enough to catch the water and core.


----------



## markb (Jun 11, 2009)

thanks for the quick reply. 

But you never had a problem with water splashing out from the top of the bucket while he was holding it to the ceiling?


----------



## SlickRick (Sep 3, 2009)

jj's right. You can rig up a pump sprayer to it instead of a hose. plenty of water. Done many, many holes. Cover as needed. Line your apprentice up with the pilot hole. 5 gal bucket. You are good to go. After the first one you'll feel better.


----------



## markb (Jun 11, 2009)

Got one of those. Great things. Let me ask you something. I'm fairly new to this coring business. We used to sub out the coring, but recently we bought our own machine (and I can't believe how handy it is). 

Maybe I am a bit naive, but coring doesn't seem like rocket science. There are a few instances such as cutting through re-bar that get a bit tricky though. My question is: is there more to it that I am neglecting to think about? And any tips on cutting those bloody re-bars faster?


----------



## SlickRick (Sep 3, 2009)

markb said:


> Got one of those. Great things. Let me ask you something. I'm fairly new to this coring business. We used to sub out the coring, but recently we bought our own machine (and I can't believe how handy it is).
> 
> Maybe I am a bit naive, but coring doesn't seem like rocket science. There are a few instances such as cutting through re-bar that get a bit tricky though. My question is: is there more to it that I am neglecting to think about? And any tips on cutting those bloody re-bars faster?


Your right it is not rocket science. Ease through the re-bar remember you are buying the bits. We used to core so many holes, we would just stand on the machine up to 6" You are on the right track.


----------



## curtis2kul (Sep 14, 2008)

Hilti drills and bits are the best!

We catch cores in 5 gallon buckets all the time during upfits. Its a pain but you have to do it. Just make sure you empty the bucket after each drill. One time i had a guy say that the bit hit his finger as i made it through the floor. Needless to say it was after about 3 drills and the bucket has some water in it. :furious:


----------



## Christina (Jul 14, 2009)

markb said:


> thanks for the quick reply.
> 
> But you never had a problem with water splashing out from the top of the bucket while he was holding it to the ceiling?


 








Excuse the paint picture I made...  Just an idea...


----------



## Christina (Jul 14, 2009)

curtis2kul said:


> hilti Drills And Bits Are The Best!
> 
> We Catch Cores In 5 Gallon Buckets All The Time During Upfits. Its A Pain But You Have To Do It. Just Make Sure You Empty The Bucket After Each Drill. One Time I Had A Guy Say That The Bit Hit His Finger As I Made It Through The Floor. Needless To Say It Was After About 3 Drills And The Bucket Has Some Water In It. :furious:


Yes!! *hilti!!*


----------



## markb (Jun 11, 2009)

slickrick said:


> Your right it is not rocket science. Ease through the re-bar remember you are buying the bits. We used to core so many holes, we would just stand on the machine up to 6" You are on the right track.



WHAT! :blink:You would just stand on the drill! You can do that? Never had a problem? That just sounds crazy to me lol. I can only imagine spinning around at 600RMP:laughing:


----------



## Airgap (Dec 18, 2008)

Sometimes we use a leak diverter under a coring hole. It's like a big flexible funnel with a hose connection on the bottom. It's designed to catch leaks, but it works great for what you need. I'll post a pic and link tomorrow. You can pick one up for less than 50 bucks. 4 bungees or ropes you can tie it up where you need it. It'll catch small cores, water, everything.


----------



## markb (Jun 11, 2009)

Christina said:


> Yes!! *hilti!!*


We use Hilti bits, but bought the Milwaukee drill with the clutch. Not sure why anyone would want the one with the shear pins though. anyhoo...good drill too. No problems so far.


----------



## SlickRick (Sep 3, 2009)

markb said:


> WHAT! :blink:You would just stand on the drill! You can do that? Never had a problem? That just sounds crazy to me lol. I can only imagine spinning around at 600RMP:laughing:


Many,many,many times..


----------



## Christina (Jul 14, 2009)

markb said:


> WHAT! :blink:You would just stand on the drill! You can do that? Never had a problem? That just sounds crazy to me lol. I can only imagine spinning around at 600RMP:laughing:


Hey! New occupation for me... I could wear a pink too-too and stand on the coredrill... BALERINA!! :laughing:

Sorry, I had to laugh Slick.


----------



## markb (Jun 11, 2009)

Airgap said:


> Sometimes we use a leak diverter under a coring hole. It's like a big flexible funnel with a hose connection on the bottom. It's designed to catch leaks, but it works great for what you need. I'll post a pic and link tomorrow. You can pick one up for less than 50 bucks. 4 bungees or ropes you can tie it up where you need it.


I would love to see what it looks like. Anything to shorten time to core holes. Right now it takes about 40 mins for a 4" hole. From setting up the machine to removing the core. I want to see us being able to do it in half the time, if possiable. So anything that makes it faster and safer I'll try. Maybe I'll get my helper to stand on the drill tomorrow  That's one way to speed things up.


----------



## Optimus Primer (May 20, 2009)

that 5 gallon bucket fills with water fast. I drill pilot holes to locate underneath, then pack it full of putty. That helps alot for the guy underneath. Have some walkie talkies available so if it gets to heavy you can stop. Also, just in case, make sure it's not a post tension slab. You dont want to cut one of those cables. If youre real good, you can catch the core with the bit so it doesnt fall below.


----------



## SlickRick (Sep 3, 2009)

They don't produce very much torque. We did a lot of hospitals and hotels that way. Saved a lot of time..


----------



## Optimus Primer (May 20, 2009)

The ones you can stand on, you can bolt down with a redhead. Also dont force the bit. Go slow and it wont catch and spin you around if its not bolted down.


----------



## markb (Jun 11, 2009)

slickrick said:


> They don't produce very much torque. We did a lot of hospitals and hotels that way. Saved a lot of time..


What didn't produce very much torque


----------



## SlickRick (Sep 3, 2009)

markb said:


> What didn't produce very much torque


The drills themself. They just seem bad a$$ The bit is doing the cutting.
Like hp said, plug up your pilot hole.


----------



## Airgap (Dec 18, 2008)

These are close to what we use, but not as sturdy. Same concept.


----------



## Titan Plumbing (Oct 8, 2009)

As said, stand on the drill base, plug the hole and have a helper cacth the core...problem solved. I have done WAY more than 30 this exact way.

Just have someone with a wet vac cleaning the water around the hole topside...you'll be amazed.


----------



## ILPlumber (Jun 17, 2008)

Good tips above.

I use a milwaukee rig that has a vacuum plate. Turn the vac pump on and it sucks down tight on the floor. I also use a vacuum ring around the entire bit and drill. Hook a shop vac to the ring and the surrounding area stays clean.

Now, as for the bottom. In a finished space. We tape visqeen plastic to the ceiling draped down into a trash can. When the bits falls through it slings water around pretty good. Watch the joints in the steel decking material. The water will run between the concrete and the decking and drip out at the joint.

We use a 5 gallon pump up jug with the garden hose attached to the rig (also made by milwaukee) 5 gallons of water should drill at least 4 holes through a 4" deck. To little water and it goms up the bit. Too much water and it won't cut efficiently. 

A typical 5" hole should take you around 10 minutes start to finish.

For horizontal cores through masonry walls or just a few holes through a floor I use a dynatech handheld rig. It works sweet for RB65 woodford hose bibs and small to medium pipe penetrations. Both my rigs are pictured below. They have paid for themselves many times over.


----------



## user4 (Jun 12, 2008)

It really isn't that hard to drill a pilot hole to determine the thickness of the floor and then set up the core rig to core the hole dry for the last half inch, and minimizing the water damage to the lower floor, unless you are coring through flexi-core.


----------



## SPH (Nov 4, 2008)

we normally raydar the floor first to make sure there are no conduits where we want to go, also allows us to dodge any large rebars.


----------



## M5Plumb (Oct 2, 2008)

Have a wet dry vac on top, along with a spray bottle, the bucket below and away you go. On the rebar issue, this makes me think post tension slab...Doh! Hit one of those cables and you're in the $hit box. I have used Acuren inspection service for GPR in the slab just to be on the safe side. They mark everything out in your core areas, ust a thought to share on the GPR of course.


----------



## Bayside500 (May 16, 2009)

someone makes a round ring that you plug into a shop vac with holes on the inside of the ring to pickup excess water, i have seen it before and works great.

i use a ring of plumbers putty around the hole and a pump sprayer to add the water, it doesn't take much water to keep the bit cool.

and the drop in anchor and a piece of 3/8" rod to hold the machine down is a great idea as well.


----------



## ILPlumber (Jun 17, 2008)

It is much better for the bit to run the water from inside the bit to out the top of the cut while drilling. This removes all the material being cut out.


----------



## markb (Jun 11, 2009)

Killertoiletspider said:


> It really isn't that hard to drill a pilot hole to determine the thickness of the floor and then set up the core rig to core the hole dry for the last half inch, and minimizing the water damage to the lower floor, unless you are coring through flexi-core.


Great idea. Have a good wet core, vacuume up the remaining water and dry cut the last inch.


----------



## RealLivePlumber (Jun 22, 2008)

Why not jam a 2x4 under the bucket, from the floor, to hold it tight to the ceiling?


----------



## mudbrrk (Nov 8, 2009)

When you know the thickness of your slab, mark your bit about half an inch less than that with a permanent marker. When you get to that mark pull the bit out and break off the core with hammer and chisel and remove it from the slab. Vacuum out the water that has collected in the hole. Then you finish the hole dry and have minimal blowout below.


----------



## ILPlumber (Jun 17, 2008)

If you are the guy buying the core bits. Don't dry core.

Usually you are drilling through corrugated steel deck also. So then you are dry coring the last 2" to keep the area below from getting wet?

Not with my bits.


----------



## markb (Jun 11, 2009)

Do you really think that a little dry coring will cause a lot of damage to a bit?


----------



## ILPlumber (Jun 17, 2008)

markb said:


> Do you really think that a little dry coring will cause a lot of damage to a bit?


 
Yes.

I have bits that are 7 years old that have never been ran dry and cut well.

I have new bits that a journeyman of mine started dry to stay dry himself with the handheld. They cut noticeably slower now. 

I don't mind if you use your bits dry. That's your perogative. I'm just trying to help...:yes:


----------



## markb (Jun 11, 2009)

Note taken. 

Maybe you may be able to shine some light on this. I have a problem when cutting some holes. About halfway through core, I can't get the bottom of the bit cooled down. Maybe the water isn't reaching the tip of the bit? Am I pumping too much? Or not enough? (which isn't the case, because at these points I just keep on pumping). But my cores always end up dry at the end (thus getting stuck inside of the bit)


----------



## ILPlumber (Jun 17, 2008)

markb said:


> Note taken.
> 
> Maybe you may be able to shine some light on this. I have a problem when cutting some holes. About halfway through core, I can't get the bottom of the bit cooled down. Maybe the water isn't reaching the tip of the bit? Am I pumping too much? Or not enough? (which isn't the case, because at these points I just keep on pumping). But my cores always end up dry at the end (thus getting stuck inside of the bit)


I work the bit in and out as I drill every 10 seconds or so. This pushes the spoils out as you plunge the bit back in the hole. If they get all mucked up in there, water won't be able to cool the bit/ push the spoils out.

Pumping the crap out of it will only build so much pressure. The pump up jobbies only build so much no matter how much pumping you do.

If you keep the water to it, thus keeping the hole clean, the core will usually fall out the bottom (catch it in something) 

Speaking of blocking the water, if you are drilling mutiple layers of brick. Sometimes a brick will lodge in the bit preventing you from advancing and keeping water from getting to the cutting "teeth"

Doing all my own cutting and coring saves me a whole lotta $$.


----------



## markb (Jun 11, 2009)

That's some good advice. Thanks. I think that might have been my problem. I never let the dirty water out, and the pump could not overcome the pressure already held in the bit. 

I don't mind coring. It's a nice change from day to day plumbing. 

Did you find that the machine paid for itself rather quickly?


----------



## ILPlumber (Jun 17, 2008)

1. Yes, both my machines paid out quickly.
2. I no longer have to schedule/wait on a coring company.


----------



## Bill (Jun 17, 2008)

I have a Milwaulkee rotery hammer drill which will take up to a 6" core bit. I never used it for that yet.


----------



## mudbrrk (Nov 8, 2009)

ILPlumber said:


> If you are the guy buying the core bits. Don't dry core.
> 
> Usually you are drilling through corrugated steel deck also. So then you are dry coring the last 2" to keep the area below from getting wet?
> 
> Not with my bits.


Half an inch...not 2"...big difference....run it wet too...whatever...only a small amount of water...still a lighter catch below.


----------



## ILPlumber (Jun 17, 2008)

mudbrrk said:


> Half an inch...not 2"...big difference....run it wet too...whatever...only a small amount of water...still a lighter catch below.


Please explain to me how you are only dry coring the last half inch in a corrugated steel deck. When the bit pokes through the upper part of the corrugation there will be an inch and a half to go through the lower part.


----------



## user4 (Jun 12, 2008)

ILPlumber said:


> 1. Yes, both my machines paid out quickly.
> 2. I no longer have to schedule/wait on a coring company.


The last plumbing co. I worked for did almost no coring whatsoever, and subbed all of it out, to save money on liability.


----------



## ILPlumber (Jun 17, 2008)

Killertoiletspider said:


> The last plumbing co. I worked for did almost no coring whatsoever, and subbed all of it out, to save money on liability.


I gotta carry so much friggin insurance, a little coring isn't going to matter.:laughing:


----------



## user4 (Jun 12, 2008)

ILPlumber said:


> I gotta carry so much friggin insurance, a little coring isn't going to matter.:laughing:


The older buildings in the Gold Coast have a three foot space between floors, the ceiling below is plaster, some of which are domed ceilings with hand painted murals on them, depending on the artist that painted the mural a mistake could cost 4 mil or more.


----------



## ILPlumber (Jun 17, 2008)

I just finished a job like that. We ended up hanging unistrut trapeze with 3/4" osb screwed to it to protect the ceiling below and have a place to crawl around on to run the new drains.


----------

