Drilling some weird concrete.

[Alchymist]

Installing tapcon style screws in concrete garage floor. 3/16" masonry bit, 1/2" drill. Would love to have used my hammer drill but it's SDS and I did't have one that size. Anyway, first few holes went OK. Next hole drill went in about 1" and stopped dead. No amount of pressure would make it cut. Moved to next hole, drilled OK. Long story short, took 3/16" twist HHS drill and finished those holes that the masonry bit wouldn't drill completely. Thought it might have been hitting rebar, but no metal shavings on any of the stubborn holes, nothing but concrete dust coming up. Besides, rebar shouldn't be an inch down from the top. An the holes were spaced oddly where the problems occurred.

 

[DekeT]

Did you hit some course aggregate? Dull your bit?

 

[DYNA BILL]

Rock.

 

[WNYflyer]

Yup, I would say a rock. I get it all the time in my garage's concrete block walls at the cores filled with concrete. Also had the same problem at the basement walls. Had to put plenty of oooomph behind the drill to get through and get the hole deep enough. Slow going but my old drill has been up to the task.

 

[brownbagg]

you hit rebar

 

[Alchymist]

Did you hit some course aggregate? Dull your bit?

Nope, doesn't dull the bit, just stops it cold. Course if I set on it and let it spin, I would imagine it would burn. It drilled subsequent holes ok.

Rock.

Ya think?Then how would a HSS twist drill go through it? Ever try drilling rock with a twist drill bit?

 

[joes169]

You'd be wise to invest in a $5 SDS bit, as it will outlast the "cheapy" bit's included in the box of Tapcons probably 10:1. Not to mention, it will allow you to use a hammer drill, which is exactly what it's intended for.......

 

[Alchymist]

you hit rebar

Don't think so, no metal shavings ....

I've drilled plenty of masonry of various types - one reason I own a hammer drill. Never ran into anything that would stop a carbide masonry bit then drill with a twist drill - without leaving steel shavings.

 

[Alchymist]

You'd be wise to invest in a $5 SDS bit, as it will outlast the "cheapy" bit's included in the box of Tapcons probably 10:1. Not to mention, it will allow you to use a hammer drill, which is exactly what it's intended for.......

$3.50 for the masonry bit - job done. Yeah, had an SDS in 3/16 been available, I would have, but ......

 

[DYNA BILL]

Ya think?Then how would a HSS twist drill go through it? Ever try drilling rock with a twist drill bit?

Hmmm...Dunno. I missed the part where you said you finished it with a HSS twist drill.

 

[joes169]

$3.50 for the masonry bit - job done. Yeah, had an SDS in 3/16 been available, I would have, but ......

Just to be sure I understand, you were drilling w/o any hammering or percussion action, correct? If so, then it's extremely common for the bits to hit a hard stone and struggle, or completely stop. There's nothing more than a dull piece of carbide brazed on to the end of the bit. It's designed to be used in a hammer drill regardless of the shank on it. And even though it doesn't seem like it would matter much, the SDS bits work far better IMO whether they're chucked in an SDS, or even a small cordless drill with a hammer function. The carbide is of much better quality than a standard "cheepy" masonry bit. If you ever need to find a 3/16" SDS bit, they should have a few different lenghts at HD, or similar big boxes............

 

[BFBOB]

Heeeeere come the Grammar Police!

Your SDS drilling device is a ROTARY HAMMER.
A hammer drill is a toy.

Drives me nuts, like folks saying flathead when they mean slotted.

 

[Alchymist]

Just to be sure I understand, you were drilling w/o any hammering or percussion action, correct? If so, then it's extremely common for the bits to hit a hard stone and struggle, or completely stop. There's nothing more than a dull piece of carbide brazed on to the end of the bit. It's designed to be used in a hammer drill regardless of the shank on it. And even though it doesn't seem like it would matter much, the SDS bits work far better IMO whether they're chucked in an SDS, or even a small cordless drill with a hammer function. The carbide is of much better quality than a standard "cheepy" masonry bit. If you ever need to find a 3/16" SDS bit, they should have a few different lenghts at HD, or similar big boxes............

Y'all are missing the point - the drill stops dead - it goes through the first inch like it was drilling butter (well, almost). The next hole the bit works OK again, usually to full depth (~2"). Yes, no "hammer" action. The nearest big box store is 22 miles away. Hence the $3.50 bit locally. It worked for all but about 4-5 holes. Still drilling ok when I finished.

 

[Bob C]

Y'all are missing the point - the drill stops dead - it goes through the first inch like it was drilling butter (well, almost). The next hole the bit works OK again, usually to full depth (~2"). Yes, no "hammer" action. The nearest big box store is 22 miles away. Hence the $3.50 bit locally. It worked for all but about 4-5 holes. Still drilling ok when I finished.

Still seems to me you drilled an inch or two easily. That is the cream of the crete, and then it just stopped. Sorry, but rocks is next under the cream, and with twist action only, no percussion, I can see the bit stopping dead. Percussion would split the rocks and allow you to continue, but you already know this.

 

[joes169]

Still seems to me you drilled an inch or two easily. That is the cream of the crete, and then it just stopped. Sorry, but rocks is next under the cream, and with twist action only, no percussion, I can see the bit stopping dead. Percussion would split the rocks and allow you to continue, but you already know this.

Exactly as Bob stated, don't expect good results from a non-hammer drill in concrete................

 

[Justanoldguy]

I'd be worried if there was an inch or two of cream on the top of my concrete.
That **** is not hard concrete.
Any concrete that I have done is mixed thoroughly right through and a scim
of slurry on top when it it finished.

 

[VolvoMan]

Heeeeere come the Grammar Police!

Your SDS drilling device is a ROTARY HAMMER.
A hammer drill is a toy.

Drives me nuts, like folks saying flathead when they mean slotted.

Woooo Woooooo Wooooo - Grammar Police, Internal Affairs.

Ahem, in this context, SDS drills are refered to correctly as Rotary Hammer Drills. However, SDS is actually a chuck system commonly used on Rotary hammer drills, it can also be found on many other types of professional grade powertooling.

Rotary Hammer is also a misnomer as the Hammer part does not rotate at all, rather, it exerts a piston action on a separately rotated chuck. Hammer drills on the other hand have a rotating hammer action (just to confuse the issue).

What's this mean to our intrepid concrete driller? not much more than the fact that Rotary hammer drills are specifically designed for eating through heavy masonry & concrete like butter and most SDS drill bits are designed with that in mind. Standard Masonry bits on the other hand, are pitched at the amateur home improvement guy who is expected to only occasionally drill a hole in a brick wall to put up a picture.

If I was the OP, I'd actually be a little concerned the drilling wasn't tougher with the standard drill, unless of course it's had a thick screed coat laid down on the top, in which case I'd want to drill down another couple of inches.

 

[Alchymist]

If I was the OP, I'd actually be a little concerned the drilling wasn't tougher with the standard drill, unless of course it's had a thick screed coat laid down on the top, in which case I'd want to drill down another couple of inches.

Who knows what the concrete is -

Sometimes the masonry drill went all the way in, about 2-1/2 inches, other times it stopped at 1", then I needed the twist drill to continue. In any case, the drill was turning fairly slow with my full weight on it. The powder in both cases looked pretty much the same - no color change, same consistency.

Not too worried about it, as the tapcons are only holding down metal track for rolling shelves. More for positioning than holding down.

 

[MScott]

When I was remodelling my daughers place I had to drill about 100 holes for tapcons to install drycor flooring. I was only getting about 3 or 4 holes with the drill bit supplied with the tapcons even when using a hammer drill. Same thing, the bit would go in a ways, then stop. Forcing it only burned out the bit. It seems this was old concrete, hand mixed and probably using crushed granite rather than the crushed limestone used today and so much harder.
I ended up buying a Bocsh SDS rotary drill and was able to drill the remainder of the holes with one bit.

 

[VolvoMan]

Who knows what the concrete is -

Sometimes the masonry drill went all the way in, about 2-1/2 inches, other times it stopped at 1", then I needed the twist drill to continue. In any case, the drill was turning fairly slow with my full weight on it. The powder in both cases looked pretty much the same - no color change, same consistency.

Not too worried about it, as the tapcons are only holding down metal track for rolling shelves. More for positioning than holding down.

It really sounds to me like either there's an over-thick screed on the top of the slab, or someone over worked the slab, this causes all the big bits to sink to the bottom, leaving just cement on the top layer (also happens with over-wet mixes). Not a big deal for what you're doing, but if you consider installing anything in it that relies on strength (like a 2 post lift), I'd have it checked out by a good contractor and drill as deep as possible.

 

[Charles (in GA)]

Heeeeere come the Terminology Police!

Your SDS drilling device is a ROTARY HAMMER.
A hammer drill is a toy.

Drives me nuts, like folks saying flathead when they mean slotted.

There, fixed it for 'ya

no problems with the grammar by the OP, just that he may have used a less than perfect term for the tool.

Charles

 

[Alchymist]

Heeeeere come the Grammar Police!

Your SDS drilling device is a ROTARY HAMMER.
A hammer drill is a toy.

Drives me nuts, like folks saying flathead when they mean slotted.

Tell it to Bosch:
http://www.cpotools.com/bosch-hammer-drills/bosch-hammer-drills,default,sc.html?ref=googaw&kw={keyword}&gclid=CMnGttmR9bECFQhN4AodN0MABQ&keyword=hammer+drill

Tell it to Milwaukee:
http://www.northerntool.com/shop/to... drill&mkwid=sI1ese3gv&pcrid=15585381071&mt=e

Best of all, tell it to Hilti:
http://hiltihammerdrill.com/

 

[70redbee]

If it were just a pc. of hard rock and not steel, you could break up the rock by putting a punch in the hole and hitting it with a hammer. This would break up the rock and let you continue. Done it many times to get a job done.For the record, I have finished holes in concrete with a HSS to finish a job, if that is all I had. Whatever it takes!

 

[Justanoldguy]

Tell it to Bosch:
http://www.cpotools.com/bosch-hammer-drills/bosch-hammer-drills,default,sc.html?ref=googaw&kw={keyword}&gclid=CMnGttmR9bECFQhN4AodN0MABQ&keyword=hammer+drill

Tell it to Milwaukee:
http://www.northerntool.com/shop/to... drill&mkwid=sI1ese3gv&pcrid=15585381071&mt=e

Best of all, tell it to Hilti:
http://hiltihammerdrill.com/

.. Well said ..

 

[VolvoMan]

Tell it to Bosch:
http://www.cpotools.com/bosch-hammer-drills/bosch-hammer-drills,default,sc.html?ref=googaw&kw={keyword}&gclid=CMnGttmR9bECFQhN4AodN0MABQ&keyword=hammer+drill

Tell it to Milwaukee:
http://www.northerntool.com/shop/to... drill&mkwid=sI1ese3gv&pcrid=15585381071&mt=e

Best of all, tell it to Hilti:
http://hiltihammerdrill.com/

Ummmmmm,

1: None of those links refer to the manufacturer's website

2: They mostly refer to Hammer drills correctly, as in those colorfully described as "Toys" that with one exception from Milwaukee, don't have recommendations for drilling in Concrete (cement isn't concrete)

3: The Hilti one is a blog that's been set up to earn money from advertising when grabbing search referrals, and incorrectly references one of Hilti's Rotary Hammer Drills as a Hammer drill.

Hear it from Bosch:
http://www.boschtools.com/Products/Tools/Pages/BoschProductCategory.aspx?catid=1007

From Milwaukee
http://www.milwaukeetool.com/tools/rotary-hammers-and-hammer-drills

And finally from Hilti:
http://www.us.hilti.com/holus/page/module/product/prca_catnavigation.jsf?lang=en&nodeId=-57795

Oddly enough Bosch and Milwaukee seem to use and omit the word Drill without clear pattern (and I'm not going to collate their product portfolio to work out why), But I'd go with Hilti any day.

 

[Justanoldguy]

(cement isn't concrete)

Try telling that to most of America who wrongly refer to concrete as cement.
Especially Texas it seems.