Question on drill concrete

[rbahr]

Hi All,

I need to drill 16 1" x 1" holes in concerete. I would REALLY like flat bottom holes and somewhat clean sides.

What should I use for a drill & bit. I would prefer to not buy a SDS drill if possible.

Thanks

Ray

 

[JoeMcGov]

You're going to want a SDS drill & bits. And get ready to spend some bucks. Consider checking with one of your regional commercial construction supply companies. If you have a White Cap Industries branch you could start there.

 

[rbahr]

That sounds expense for 16 small holes! What kind of bit will give me a flat bottom hole

 

[JoeMcGov]

That sounds expense for 16 small holes! What kind of bit will give me a flat bottom hole

I'm not familiar with a drill bit that will do that. Could you use the conventional "pointed" drill bit and then just fill the bottom with a bit of a grout like product to make it "flat?"

 

[65ranchero]

What about a coring bit, drill down to a your depth and then take a chisel and knock the center to the side and remove.
slow and steady and water.
It makes a pretty clean flat bottom but not perfect.
I have seen this done when I had railings installed.
Google 1" coring bit. Here is a example https://www.amazon.com/dp/B07HF8XD9G/?tag=atomicindus08-20

 

[FMB4]

There's some good info on this thread.

 

[23ford]

OP why do you need a flat bottom whole?

 

[FMB4]

OP why do you need a flat bottom whole?

Good question. But that's what OP wants. Meanwhile, I wonder if you could drill the holes with a standard masonry bit and then grind the end of said bit flat like a bottoming drill bit and go from there?

 

[mike93lx]

What is a 1"x1" hole? A square? Or a 1" Diameter?

If square, nothing is going to do that other cutting it larger and forming the opening you want.

Why a flat bottom hole? That is another wierd one.

Either way, the is not a job for a regular hammer drill and is squarely in SDS territory.

 

[PoorUB]

The flat bottom is going to be an issue no matter what type of bit you use. A standard masonry bit will leave a shallow V at the bottom. With a core drill the "core" will break of how ever it wants too and leave "god only knows" what the bottom will be like.

Rent a SDS drill and bit, should cost $50-$100 for four hours.

 

[ace10]

Depth?
Rebar?

 

[rbahr]

Thanks all,

With the help of good ol flebay, I picked p a Bosch SDS+ drill, now will need to pick it up. That said, no rebar, depth of hole is 1" with a 1" diameter.

Why I need to do this: I need to corner balance & align my race car. EVERY time I need to set up scales, it takes me ~2 days to get the scale stands flat and level at each corner. My garage floor is anything but flat - I see ~1.75" of change front to rear and perhaps 1/2" front to back for the scales. BTW I am trying to get these flat and even to ~ 1/8"

My solution to this is to sink 4 'cups' for each scale in the floor. I will just use 1" AL with the center bored out. I will use threaded rod to sit in these 'cups', spend the time once to get everything level and flat. From then on, its just use these fixed places in the floor to set the scales up, with as the say - no muss, no fuss...

Ray

 

[mike93lx]

Overdrill and then refill with self leveler if you are careful, you should be able to get them to the right depth and even with each other

I would not worry about drilling them with the level of precision you want... A handheld drill isn't made for that

 

[JWILLIE1977]

Overdrill and then refill with self leveler

^^^^^This.

 

[FredWanaker]

yeah, you want SDS. I went thru four or five regular good quality masonry bits trying to drill some holes. Bought an inexpensive HF SDS hammer drill and a Bosch SDS bit, 5 minutes later all the holes were done. Damn amazing how well those SDS hammer drills work.

 

[eejack]

I will use threaded rod to sit in these 'cups', spend the time once to get everything level and flat. From then on, its just use these fixed places in the floor to set the scales up, with as the say - no muss, no fuss...

Ray

You could just skip the cup and install drop-in anchors for whatever size threaded rod you wish.

 

[ConCretin]

Just for the record. SDS just refers to the type of shank the drill bit has. For example, the same bit could have a splined shank. Within the SDS family there are several sizes including SDS plus and SDS max. Both types are used in a hammer drill, which uses a carbide tipped drill bit to pulverize rather than cut the substrate. In the old days they used a hammer and a star bit that was rotated by hand. Carry on.

 

[rbahr]

eejack: I thought of that, but the threaded rod will sit in nuts that will locate the platform for the scales. That way, it is easy to individually adjust each corner.

LLWillysfan: I ended up with the SDS Plus version

All: good idea on the self leveler - thanks

Ray

 

[CraigStu]

You are going to love that drill. I am 73 and never got a hammer drill but last summer I needed to mount a 2x4 on a poured concrete foundation so I could hang gardening tools from hooks. I figured, buy the Tapcon bolts and bit and go for it. What the heck I only need 3-4 holes. Standard drill did dang near nothing. Huuuum, this isn't working so well. Lowes had a Milwaukee corded hammer drill for $99 so I bought it. WOW>>>>>>>>>that thing drilled into the concrete like it was a hard wood. I was so blown away that I even timed the second hole. It was just under 60 seconds.

 

[Sumboodie]

What sort of race car is THAT fussy?

Last time I weighed my car, it was on pavement.

 

[mike93lx]

What sort of race car is THAT fussy?

Last time I weighed my car, it was on pavement.

guessing one that has a lot of money ******* in it, and/or a lot of money on the line

 

[Relax]

Just for the record. SDS just refers to the type of shank the drill bit has. For example, the same bit could have a splined shank. Within the SDS family there are several sizes including SDS plus and SDS max. Both types are used in a hammer drill, which uses a carbide tipped drill bit to pulverize rather than cut the substrate. In the old days they used a hammer and a star bit that was rotated by hand. Carry on.

I drilled 4 holes in my residential concrete floor with a "standard" hammer drill and masonry bit, no problem.

OP, if your car is that picky that the bottom needs to be flat, you might want a drill with a quality built-in level so the holes are plumb. Unless there's a technique I'm not aware of (I don't do a lot of drilling where that matters).

 

[mike93lx]

I drilled 4 holes in my residential concrete floor with a "standard" hammer drill and masonry bit, no problem.

OP, if your car is that picky that the bottom needs to be flat, you might want a drill with a quality built-in level so the holes are plumb. Unless there's a technique I'm not aware of (I don't do a lot of drilling where that matters).

Hammer drills work fine for small holes and infrequent use.

But a proper sds hammer will always be better

 

[jrsavoie]

eejack: I thought of that, but the threaded rod will sit in nuts that will locate the platform for the scales. That way, it is easy to individually adjust each corner.

LLWillysfan: I ended up with the SDS Plus version

All: good idea on the self leveler - thanks

Ray

And very hard to get that exact with an sds masonary bit. Even when starting small and stepping up.

Maybe get some 1" round. 1/4" stainless blanks to put in the bottoms of the holes

A ll Hammer drills are not created equal. Just like anything else I would get one rated for bigger than the biggest hole you are thinking about drilling.

A lot of times you can find them for sale, with bits, for a reasonable price

 

[Kaizen]

The bosch sds I got is great. Only a couple hundred at hd. Got it after i spun a few anchors on my new lift install. I had got a brand new hammer drill and it was not good enough.
Used the hammer function all summer repointing my stone foundation. Yea the bits are expensive but i don't hesitate when i need to drill anymore as i know it will be a two min task.

 

[PoorUB]

I hate to admit it, but I have a cheap Harbor Fright SDS hammer drill. I also am afraid to admit I would buy one again! I don't use it much, but I used Hilti drills when I did HVAC and this el-cheepo drills just as fast as a $1500 Hilti. Also the HF SDS drill bits are good quality. I needed to drill twenty 1/2" holes on concrete and bought two HF bit sets thinking one would never do it. I have not taken the second set out of the package. I also bought a set of HF SDS chisels and no complaints on them either. I have loaned it out a few times and people bring it back and are surprised how well it works. At the time it was on sale for $89, regular price was twice that, or $179.

https://www.harborfreight.com/power-tools/demo-hammers/sds-masonry-flat-chisel-set-3-pc-63046.html

https://www.harborfreight.com/8-in-sds-masonry-bit-set-6-pc-62791.html

 

[rbahr]

Sumboodi: This is the car, WRT alignments - details are important, more details, better alignment...




Relax: After drilling the holes, I will machine some AL flat bottomed cups that will sit in the holes, and the standoffs will sit in these

PoorUP: I picked up a used Bosch SDS+ drill

Thanks for all your help!

 

[yugami]

If your still thinking about flat bottomed holes Diablo has a SDS Plus bit called a Rebar Demon that creates a not exactly flat bottom, but a much more flat bottom than a spade style.

 

[rbahr]

Great, thanks. I saw those listed