Drilling concrete?

[Denee007]

Regarding having not given up on the Maxjax~ my husband was concerned about some of the fine cracks running here and there in MY garage, but I spoke with Dannmar, though he can't tell me it's completely through cracks, it would probably still be ok if the thickness is adequate.

So determined I am, I took my HF hammer drill and drilled a 3/8" hole and the drill bit was only 4"(actually 3.75"), but went all the way without going through to dirt, then I took the largest drill bit(says 22 on it, about 11/16") that the kit came with, got about 2.5" and it has just quite drilling downward~ just sits there hammerdrilling. I blew out the hole with compressed air, looked, took a magnet suspecting rebar, but nothing pulled on my magnet. I took the pointed looking attachment using the hammer option only thinking maybe it's just a rock, reattached the large drill bit being used, and still didn't go anywhere! The pilot hole is down further than the larger hole. So does it sound like the bit was dulled? I'm just using the weight of the drill with a little push only. Is it just a cheap drill bit? I have an Ace hardware nearby, perhaps I can buy a good quality 5/8" concrete bit that's required by Dannmar and see if that works.

Any suggestions would be greatly appreciated I truly would like the Maxjax!
dne'

 

[bimmer1980]

some of the "cheaper" hammer drills do not have enough hammering force to knock thru some of the rock in the concrete.....

which drill do you have from harbor freight?

I was just using our Hilti hammer drill from work to drill 7/16" holes in concrete and it did them in about 1 to 2 minutes per hole. and that was going about 7" deep.

I have used a "cheaper" drill in the past on a projet and it can be tough drilling..... I would recommend trying to rent or borrow a larger hammer drill.....

best of luck!

 

[ratdoggy]

some of the "cheaper" hammer drills do not have enough hammering force to knock thru some of the rock in the concrete.....

which drill do you have from harbor freight?

I was just using our Hilti hammer drill from work to drill 7/16" holes in concrete and it did them in about 1 to 2 minutes per hole. and that was going about 7" deep.

I have used a "cheaper" drill in the past on a projet and it can be tough drilling..... I would recommend trying to rent or borrow a larger hammer drill.....

best of luck!

X2 on the Hilti. You would not believe how well they work

 

[Dolfan]

The one recommendation I would have for any MaxJax installer is to spend $30 for a rental of a proper hammer drill if you don't already own one or have one to borrow. My Black and Decker and I worked way too hard putting in 10 holes!!!!!

Get a good 7/8" bit and a proper hammer drill for sure!

 

[Possum]

Listen to these guys. The difference between using a real concrete drill and a cheap hammer drill is huge.

 

[Ign]

some of the "cheaper" hammer drills do not have enough hammering force to knock thru some of the rock in the concrete.....

Yep, if not rebar I'd suspect a rock too.

 

[drmoonshine]

Quality counts. Especially when installing a Maxjax.

 

[Denee007]

HI, I do appreciate everyone's reply and advice, but I really think this drill can do the job. I stopped by ACE hardware and bought a Dewalt 5/8" x 6" bit and it drilled right through to the dirt with no problem. But still when I put that HF bit in, it just acts like a dulled out drill bit! I'm going to get ACE to order me the 7/8" drill bit required to install the MJ lift and see if that will go the rest of the way.

 

[flat350]

A real hammer drill with a good SDS type bit will do it easy.We drill for drop in anchors and quick bolts every day with a cordless Hilti TE 4-A18 (or a corded version sometimes)thru sheet metal pan decks overhead under the concrete,fiber reinforced slabs,100 year old slabs and decks,precast decks and walls.Rebar will stop it,mesh usually doesn't and 100's of holes on a bit,a quality tool will make the job much easier.

 

[Falcon67]

I think your drill is fine, it's just the bit that's not working for ya. Good bit will make that concrete bow to your wishes.

 

[skamp]

Not sure if you have post tension cables in your slab but they are common in Houston. Make sure you don't drill into one of those badboys or you could be in for a surprise.

Steve

 

[Denee007]

post tension cable??

What is a post tension cable?

Not sure if you have post tension cables in your slab but they are common in Houston. Make sure you don't drill into one of those badboys or you could be in for a surprise.

Steve

 

[green.bubbly]

I am a Hilti/good it believer as well. All my life I have fought with drilling an occasional hole in concrete. Burned up a couple of cheap hammer drills and way to many bits. Finally I rented a Hilti and a good bit from HD and man oh man, what a freaking difference. I just wish I had the need to drill enough holes to justify buying one.


A post tension slab is a slab with cables running through it. The cables are then stretched tight and anchored to compress the slab.

 

[Kev442]

I have that SDS and a dull/cheap bit makes it useless. I bought a new bit and it went like butter.

 

[jhelrey]

I am a Hilti believer as well! After using a cheapie and then a Hilti. All you have to do on a Hilti is press the trigger and it does the rest. No joke!

 

[dougmac]

Can you rent a good quality Roto-Hammer? I just rented one with the bit I needed from Home Depot. It chewed through my floor like it was butter.....

 

[ct71rr]

You get what you pay for. I used a Bosch SDS demo hammer/drill to drill 65 1" holes 6" deep in solid ledge to anchor my foundation to. I also used Bosch bits. I used 1 bit for all the holes with no problems and the bit is still good. Save yourself the headache and rent a Hilti (or similar) from Home Depot (etc).

 

[6768rogues]

Do they really go to the trouble and expense of putting post-tensioning in a regular garage slab on grade? Around here the only place there is post-tensioned concrete is multistory parking garages and an occasional high rise building.

 

[2chipped]

For 1 small job your drill will do fine. Always remember when you buy a cheap tool consumables ie, blades,bits,and stones should be replaced with quality. As an example when we install stair railing into concrete,our bulk screws come with a concrete bit that lasts about 3 holes in commercial concrete . So instead of wasting time changing bits all the time ,bosch bits get chucked and used till their wore out,usually about 500 times the life.

 

[russlaferrera]

I have a HF hammer drill W/bits. Drilled 10, 5/8 holes threw 5 in concrete with no problem. Should your drill stop drilling. You may have hit a stone. Remove the drill and put a rod in the hole and hit it with a hammer. That will break up the stone. Then continue drilling.

 

[kmacht]

If you only have a few holes to drill then spending the money on the Hilti drill is going to be a waste. It is a great drill if you are going to use it multiple times for your job but for home use it is overkill. A regular hammer drill isn't cut out for this job though. It works fine for drilling into cinderblock but forget about it with hardended solid concrete. I would follow the advice posted earlier and just rent the drill for the afternoon. If you think you will have to drill some more concrete in the future then maybe look at the sds drill that harbor freight sells. I bought one when I built my garage and the thing works great. It is one of those few tools that constantly gets good reviews from other users. It is currently on sale for only $80 right now and includes a number of sds bits. The like can be found here:

http://www.harborfreight.com/3-in-1-1-inch-sds-rotary-hammer-97743.html


Keith

 

[Denee007]

Keith, that's the hammer drill I have right now! but now I'm more concerned about this post tension thing that skamp brought to my attention! My detached garage is 40+ years old. I have a metal detector. It's said that if a slab is post tension cable, there would be something identifying it as such and there is no identifying marks anywhere, but also to check outside the perimeter for where the anchors may be located.

As for drilling, i'm thinking about using a 7/8" core drilling tool. It's diamond tipped and drills through anything and the hole looks machined when done. I've used one several years ago and it's an amazing tool! I just have to buy the bit and rent the core driller. I know this would be overkill, but I don't want achors moving EVER when I'm done!
thanks!! dne'
This link; someone talking about post tension cable.
http://67-72chevytrucks.com/vboard/archive/index.php/t-396202.html

If you only have a few holes to drill then spending the money on the Hilti drill is going to be a waste. It is a great drill if you are going to use it multiple times for your job but for home use it is overkill. A regular hammer drill isn't cut out for this job though. It works fine for drilling into cinderblock but forget about it with hardended solid concrete. I would follow the advice posted earlier and just rent the drill for the afternoon. If you think you will have to drill some more concrete in the future then maybe look at the sds drill that harbor freight sells. I bought one when I built my garage and the thing works great. It is one of those few tools that constantly gets good reviews from other users. It is currently on sale for only $80 right now and includes a number of sds bits. The like can be found here:

http://www.harborfreight.com/3-in-1-1-inch-sds-rotary-hammer-97743.html


Keith

 

[skamp]

Keith, that's the hammer drill I have right now! but now I'm more concerned about this post tension thing that skamp brought to my attention! My detached garage is 40+ years old. I have a metal detector. It's said that if a slab is post tension cable, there would be something identifying it as such and there is no identifying marks anywhere, but also to check outside the perimeter for where the anchors may be located.

As for drilling, i'm thinking about using a 7/8" core drilling tool. It's diamond tipped and drills through anything and the hole looks machined when done. I've used one several years ago and it's an amazing tool! I just have to buy the bit and rent the core driller. I know this would be overkill, but I don't want achors moving EVER when I'm done!
thanks!! dne'
This link; someone talking about post tension cable.
http://67-72chevytrucks.com/vboard/archive/index.php/t-396202.html

If it is a detached garage than you should be OK. I don't think they use post tension for detached garages. As far markings, my house is post tensioned and has no markings on the slab as far as I can find. I am close to getting the MaxJax and located my cables by using photos I took during construction and work I did with a metal detector. I am 99.9% sure I know where all of them are now. I now need to drill a test hole to make sure I have the needed depth.

You should be able to tell by looking at the edge of your foundation. You may have to dig a bit below the grass but you will see patches where they filled the holes from the cables. This picture shows the cables coming through the side of the slab. After the slab is cured for a bit they pull them tight, cut them off and patch it. Look for a different color patch that is maybe 2-3 inches in diameter.

I was lucky enough to have pictures from when they were building. The front area here is my garage. I was able to verify the positions of the cables with a metal detector.

Keep us updated on your progress.


Steve

 

[Denee007]

Hey Steve, you don't live that far from me! I'm in West Houston! When do you plan to get your MJ???
dne'

 

[c39er]

Why bother Post Tensioning a basic on ground garage slab?

 

[skamp]

Hey Steve, you don't live that far from me! I'm in West Houston! When do you plan to get your MJ???
dne'

Hopefully in the next month or so. I have to get a jack shaft garage door opener first as the current one is in the way.

Steve

 

[skamp]

Why bother Post Tensioning a basic on ground garage slab?

The theory is to help the slab from craking due to the expansive clay soil here. I am sure like most things cost is the major driver for production builders. I don't think they would do it for detached garages. In my case my gargage is attached so part of the full slab.

Steve

 

[Denee007]

As soon as I'm done painting these parts and install them, then I'll order the MJ, but holidays really slow me down with Christmas just a few weeks off! Can't wait for the holiday season to end so I can get back to work! Anyway, I'm feeling more comfortable about drillng the holes for some reason ; )