Drilling Concrete

Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.

Moderators: Harold_V, websterz, GlennW

User avatar
SteveHGraham
Posts: 6930
Joined: Sat Jan 17, 2009 7:55 pm
Location: Florida

Re: Drilling Concrete

Post by SteveHGraham » Wed Jun 13, 2018 2:41 pm

The point here is this: regardless of what they are calling big drills now, don't try to make big holes in concrete with a little $90 or $200 hammer drill from Lowe's. This is what I was trying to get across. I have a $90 hammer drill, which is very nice for many jobs, and then I have the big Makita, which I use for anything 1/4" and up in concrete. It's a joy to use, and smaller drills aren't. When I make 1/4" holes, it goes in so fast it's hard to stop it before the chuck hits the wall.

As far as I know, "rotary hammers" do nearly the same things hammer drills do, only on a larger scale. Mine will also hammer without rotating. My hammer drill always turns.

BIG. That's the point. BIG.
Every hard-fried egg began life sunny-side up.

User avatar
warmstrong1955
Posts: 3117
Joined: Thu Mar 18, 2010 2:05 pm
Location: Northern Nevada

Re: Drilling Concrete

Post by warmstrong1955 » Wed Jun 13, 2018 2:56 pm

OK.
Well....that's why I mentioned the diameter, and the length of the hole. Get into larger diameter, and length.....a real rock drill (pneumatic) is the way to go.

A good battery powered hammer drill, will do a pretty good job on concrete, 1/2" dia and below is a piece of cake. That rail we put up recently, we needed about (24) 1/2" holes 4" deep in the concrete.
We used two Milwaukee battery hammer drills. Started at about 9:00 AM on the project, and were done with the entire railing before lunch. And that included one hole that I had to get a twist drill and go through a piece of re-bar. Things that make you go &*#$@^%.

:)
Bill
Today's solutions are tomorrow's problems.

User avatar
BadDog
Posts: 4498
Joined: Wed May 17, 2006 8:21 pm
Location: Phoenix, AZ

Re: Drilling Concrete

Post by BadDog » Wed Jun 13, 2018 2:58 pm

And if you buy one, when shopping, particularly if bargain shopping, make sure the motor supports a non-rotary "hammer" setting. You'll need that for stuff like tile chisels, and breaker points/chisels, etc. Most all of the good (big) ones we are talking about do, but I seem to recall that some of the smaller/cheaper varieties had no non-rotary setting. Maybe that's only SDS?

And remember my comment on SDS-Max. I wish I had put a bit more with it when I bought mine and gotten the SDS-Max version. I'll probably take the plunge eventually, but then I'll have one that is only a subset of the other, and for an individual, that smaller is not worth much (other than I suppose tighter spaces?) when the larger is at hand...
Russ
Master Floor Sweeper

John Hasler
Posts: 795
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Drilling Concrete

Post by John Hasler » Wed Jun 13, 2018 3:38 pm

Eh, get a five pound lump hammer and a star drill. You'll be able to skip your workout that day.

BTW if you don't deadman it that wall *will* move.

User avatar
seal killer
Posts: 4413
Joined: Sat Aug 18, 2007 10:58 pm
Location: The Land Of Oz (Ahhh, Kansas!)

Re: Drilling Concrete

Post by seal killer » Thu Jun 14, 2018 10:25 am

All--

I know a lot more about the drill required! (Thanks.) But, how about the type of self-tapping(?) i-bolt I need to screw into the concrete? Just anything from Home Depot, et al? Probably not, but what?

The blocks weigh about 2400lbs each. They are made of leftover concrete from cleaning out the trucks after a load is delivered. They are not high quality pieces, for sure. The only rebar in them is the handle. (Ha! I think!)

I am GUESSING the holes should be 6" to 8" deep. I am GUESSING they should accept a 1/2" threaded i-bolt. Therefore, based on my GUESSES, what diameter holes should I create?

--Bill
You are what you write.

User avatar
BadDog
Posts: 4498
Joined: Wed May 17, 2006 8:21 pm
Location: Phoenix, AZ

Re: Drilling Concrete

Post by BadDog » Thu Jun 14, 2018 10:33 am

Use threaded "dead head" inserts (what I was raised calling them). The kind you drill oversize in the concrete, drop in the hole roughly flush, and then "set" according to the brand/instructions/design so they expand and lock in the hole. Check the ratings and plan for some head room, but I expect 1/2 inserts (bolt size) should work fine, and are available at HD/Lowes. I'm sure HD quality is less than better providers, but as long as you stay clear of the fall line, I would use HD anchors.

This is an example of what that looks like, though a much stronger type that uses epoxy/grout to lock it in. The ones I'm talking about you generally just drive into a tight hole, and the bolt flares it as you crank it in. Others have a cone and "set" tool. Others have a conical stud that you tighten down a nut on that locks it in, and leaves the stud proud. There are a variety of styles, but the flush/below surface type seem to suit your needs best.

Image
Last edited by BadDog on Thu Jun 14, 2018 10:38 am, edited 1 time in total.
Russ
Master Floor Sweeper

User avatar
warmstrong1955
Posts: 3117
Joined: Thu Mar 18, 2010 2:05 pm
Location: Northern Nevada

Re: Drilling Concrete

Post by warmstrong1955 » Thu Jun 14, 2018 10:37 am

I don't know what you mean by 'i-bolt'.
Do you mean eye bolt?

Something like this maybe? https://www.homedepot.com/p/Hilti-1-2-i ... /204993017

Other Bill
Today's solutions are tomorrow's problems.

User avatar
seal killer
Posts: 4413
Joined: Sat Aug 18, 2007 10:58 pm
Location: The Land Of Oz (Ahhh, Kansas!)

Re: Drilling Concrete

Post by seal killer » Thu Jun 14, 2018 10:38 am

Russ--

Thanks!

--Bill
You are what you write.

User avatar
seal killer
Posts: 4413
Joined: Sat Aug 18, 2007 10:58 pm
Location: The Land Of Oz (Ahhh, Kansas!)

Re: Drilling Concrete

Post by seal killer » Thu Jun 14, 2018 10:41 am

Bill--

I meant eye-bolt. I'm dain bramaged.

--Other Bill
You are what you write.

User avatar
BadDog
Posts: 4498
Joined: Wed May 17, 2006 8:21 pm
Location: Phoenix, AZ

Re: Drilling Concrete

Post by BadDog » Thu Jun 14, 2018 10:42 am

Here are some other examples that will take an eye bolt.
Image
Image
Image
Image
Image
Russ
Master Floor Sweeper

User avatar
BadDog
Posts: 4498
Joined: Wed May 17, 2006 8:21 pm
Location: Phoenix, AZ

Re: Drilling Concrete

Post by BadDog » Thu Jun 14, 2018 11:22 am

It occurs to me that you might not even need an eye bolt. Depending on how you need to fit these, you might be able to drill 2 holes in the sides above center (to keep stable in the desired orientation) and just use temporary (rebar? rod? heavy tube/pipe?) handles loaded single shear with a chain connected. The existing handle might work for one of those load carrying points. Put in place, and just pull out the "handles" to use on the next.

To state the obvious, stay very mindful of the fall line regardless of how you proceed.
Russ
Master Floor Sweeper

hanermo
Posts: 42
Joined: Tue Oct 01, 2013 5:47 am

Re: Drilling Concrete

Post by hanermo » Thu Jun 14, 2018 2:28 pm

My experiences are mostly with steel around 13.000 drilled/tapped holes in tool steels upto 16 mm,
but some 18-20 mm holes 300 mm deep in concrete.

The same applies to both jobs.
It is quite easy to drill a 5-6 mm starter hole as deep as needed.
It is then about 4-10x easier to drill a 18 mm hole after it.

A 2-sizes bigger drill will also be about 4-10x easier and faster on any hole mentioned.
So a really big and heavy (and powerful) drill will do the job 4-10x faster, and is very much less work when doing it.

To the OP, I would suggest renting a big drill of the appropriate type for one day- if all the blocks are available and can be done at once.
But 6 blocks long and 4 high .. big holes .. 2 each .. 48 big holes, deepish.
Try very hard to drill the holes vertically on the slabs, flat, before mounting.
It will be a big heavy hard job to drill 48 big horizontal holes. Likely take a full day.
Even worse, trying to drill them once mounted.

Aside:
Ground pressure may perhaps be ime much more than the retaining wall can handle, if it is only the concrete blocks as a curtain wall without any anchors.
If for any reason the ground "wants" to move, like rain, settling, sediments, subsiding due to runoff underground tilting the foundation etc.

At issue is not the "strength" of the concrete blocks or their mass.
Or the anchoring.
The curtain wall would need some form of strong anchor diagonal to the pressure to stop it from tilting, progressively, in case of issues.
I see similar walls fail several times per year here in Spain.

Concrete == 2400 kg/m3,
water/soaked soil = 1000 kg, or 4x more.
Worse, soaked soil 2.x m deep or 3 layers, is nor permeable short term.
So when more water in rain lands on the surface, it adds huge pressure on top.
The soaked soil acts like a hydraulic ram, pushed by lots of kgf of force from on top.

Much depends.
In your area it might be that such curtain walls are typical and hold up well.
Then everything is great.
The soil and drainage is right and the climate is suitable.
Then ignore my caution.

But if there is a heavy horizontal load on curtain walls, some form of anchor can make them stronger.
Ask local builders, architects, people who bought/sold houses.

In my area, approx 100% of houses have structural issues on their foundations due to water/seepage/rains and being on a hillside.
Approx 100% of new housing and mansions have the same problems, and most problems appear 5+ years after the construction.
Most construction is high value and multi-million or million+ builds.

Most-all are badly built - because there is no effective legal clawback mechanism and the major issues only appear 5 years after construction.

Post Reply