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I'm building a retaining wall out of concrete blocks. You've seen them a million times; those big (mine weigh 2400lbs each) blocks with the rebar hook in the top.
I need to deadman a few of them in two different rows. I will drill holes in the sides of the chosen blocks and screw in heavy duty i-bolts. I'll bend some 1/2" rebar into a hook and place it through the i-bolts. There's a problem, though. I've never drilled holes in concrete.
Will you tell me how to do it? What kind of bit do I need? What diameter hole should I drill? What kind of i-bolts should I use? Other stuff?
The picture below is the wall in question. That's the first row. (It is one more block long. I took the picture before I finished the row.) There will be four more rows on top of that one. Then I will backfill the area in the foreground. I don't think the wall will move, but I want to make SURE it doesn't. It wouldn't be a good thing if it leaned over into the deck!
Not sure about that particular concrete, but I've had good luck with an SDS-Plus hammer drill (mine's a Makita, rated to I think 1-1/4" IIRC?). I prefer the better Bosh masonry bits (This is one I bought for reference, currently "not available"). I tend to get the long ones for "might need it later" even if the current job doesn't need it, but cheaper to get the short ones. For eye-bolts you'll need something like a dead-head threaded anchor. As for size, not sure, but looking at ratings should answer that question. That's all I got...
Last edited by BadDog on Wed Jun 13, 2018 1:15 pm, edited 1 time in total.
Get a rock pneumatic rock drill if you need any holes which have some depth to 'em, and especially if they are larger diameter.
If you just need short holes, Hilti drills are fine. (electric hammer drills)
Both are available at rental places.
Concrete is easy to drill. Doesn't take a lot of blow energy.
I believe Russ is talking about a rotary hammer, not a hammer drill. A hammer drill is a little drill that works on small masonry jobs. A rotary hammer is a much bigger tool, and it will take special bits a hammer drill can't hold.
I have a big Makita. It goes through concrete much, much faster than a hammer drill. I used a Bosch 1/2" hammer drill to put a 5/8" hole through around a foot of concrete, and it was slow work. The rotary hammer did the same thing quickly and easily.
How big are your holes? How deep are they? These figures will tell you which tool you need.
Warmstrong apparently works in a hole made of stone, so he probably knows something about the best tool.
I don't know anything about your job, but I had to pull some concrete slugs out of my yard once, and I did it with rebar. I drilled two parallel holes into each slug, and then I poured them full of epoxy. I made U shapes from rebar and shoved them into the holes. This gave me loops to attach a chain to. Worked really well.
warmstrong1955 wrote: ↑Wed Jun 13, 2018 1:14 pmConcrete is easy to drill.
Unless luck finds you hitting the rebar!
Had that stroke of luck not long ago. Helping a friend of mine installing a 'Kee-Clamp' railing.
One hole...and hit rebar at a couple inches, and I needed two.....
Here is a 1/2" chisel bit (most common) for a hammer drill.
This one fits a CP-9 pneumatic drill. (One of those things that ends up laying in your toolbox from a job)
And....I have no idea what Steve is talking about.
In my world, a hammer drill, and rotary hammer, are synonymous. We called them Hilti Drills, as Hilti originated the species.
I've bought kazillions of 'em....electric, battery, mostly for engineers & surveyors to put in spads. The pneumatic ones, were mostly for the miners to do various tasks, like securing liners & things.
The Bosch drills I get are (according to the manuf) much better at getting through rebar than the chisel points. I have hit rebar, and it's still no fun, and I didn't have a side-by-side with the other option to test against, but it did feel like it worked better. Then again, maybe that's the justification fallacy, like the guys who swear they got both efficiency AND noticeable performance gains from a K&N type filter (when a new quality paper filter would likely have done the same or better).
I've got a spline drive bit somewhere around here that I acquired somehow. But nothing to use it. I will add that I kinda wish I had bought bigger (when do we not?) and got the SDS-Max motor. It has more power, thus more capacity, fits SDS-Plus bits as well, and adds better chisel options as well as spades that would be nice in the local Coliche...
I see hammer drill used to refer to both, and Google agrees, but I think the norm is for Manuf etc to use that for the smaller motors with standard chucks. Rotary Hammers, Combination Drills (what my Makita is actually called), and Demolition Hammer/Drills seem to exclude the smaller variety.
I tried to drill some holes in cement blocks to exit my sump pump using a regular drill and masonry bit. I quickly gave up. Fellow came over with a big rotary hammer drill. Probably took him 3-5 minutes to finish the job. That included starting the small generator for power and deciding where to drill the hole. Beg, borrow or rent the right tool.
