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Drilling through rebar in concrete

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chad215

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Caldwell,tx
I was trying to set some 5/8 redheads on a new slab for posts for a gazebo I'm building to cover a hot tub.
Drilling through the concrete is no issue but I can't get this thing to go through the rebar, even though the bit specifically states it's made for that. The bit is basically just spinning on top and not engaging and even really scratching the rebar. Is there a technique to this I'm not aware of?
I let it spin on top with moderate pressure for at least two minute but it's just riding the top of the steel.
Should I turn off the hammer and just drill? (I tried this, but there was no difference)

The below is what I'm using.
Carbide Bit
 
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strutaeng

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Last edited:
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housewolf

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strutaeng said:
Yeah, that's just a standard bit. Sometimes you can drill through if you catch the rebar off center. You probably hit it right in center.

They make spacial rebar cutters for this. Switch to the rebar cutter when the regular bit starts bouncing, then switch back once you drilled through the rebar. Some of my THD have them in stock.

Edit: https://www.homedepot.com/p/Milwaukee-3-4-in-x-12-in-SDS-Plus-Rebar-Cutter-48-20-6799/320278633
Click to expand...
I never knew that tool existed. Doing commercial plumbing I’ve drilled way more than my fair share of anchor bolts. Hitting rebar is inevitable. Sometimes (usually) it drills through, sometimes it won’t, easily. If you stick with it, most likely you’ll eventually get an hole there but the hole may be too large to set the anchor bolt. In our work, it’s almost always simple enough just to move the hole over just enough to clear the rebar. If the hole has to stay in that exact location, be prepared to epoxy that anchor in.
 
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chad215

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Caldwell,tx
strutaeng said:
Yeah, that's just a standard bit. Sometimes you can drill through if you catch the rebar off center. You probably hit it right in center.

They make spacial rebar cutters for this. Switch to the rebar cutter when the regular bit starts bouncing, then switch back once you drilled through the rebar. Some of my THD have them in stock.

Edit: https://www.homedepot.com/p/Milwaukee-3-4-in-x-12-in-SDS-Plus-Rebar-Cutter-48-20-6799/320278633
Click to expand...
Thank you! I'll report back my results in the next couple of days.
 
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strutaeng

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I only know about the rebar cutter because I'm a structural consultant and always deal with contractors hitting rebar on post-installed anchors into existing concrete. I quickly found the rebar cutter on the Hilti website many years ago when I started in the industry.

Usually, contractors will just angle the hole and try to miss the rebar, but then the installation instructions on the anchors get voided. And anchors look horrible cockeyed. Red flag for the special inspectors and I would get an request for information (RFI) asking what to do.

Our specs actually call for scanning and marking the rebar and creating a template for anchors. If a conflict occurred, we allowed the anchor to be shifted about 1" to 1 1/2". Then the holes in the steel plate would get punched in the right place. Oversized plates was a must so you didn't get an anchor bolt too close to the edge. Mind you some reactions on these connections can easily be 20,000+ lbs of service load. So a lot of heavy anchors and stuff needs to done by the book.

Few contractors do that though because it requires a lot of coordination with the contractor, steel detailer and fabricator. 🙄
 
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ConCretin

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A regular carbide bit like the one the OP is using won't cut through rebar. It might slide by but it won't cut steel. A rebar cutter will remove steel and allow you to continue drilling on your original line. One thing to note is that you don't use a hammer drill with a rebar cutting bit, they usually have a smooth shank for use in a regular drill.

One additional thing to note; a hammer drill or rotary hammer is a type of drill that creates impacts to pulverize concrete. SDS is a type of drill bit. Hammerdrills are basically all the same other than size and the type of drill bit they accept such as SDS, SDS plus, SDS max or spine drive.
 
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Rusted Nut

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The rebar is there for a reason, you don’t really want to drill through it. strutaeng has the right idea. You may have to get a different base plate. If you really want to drill the bar, get a “rebar eater”, they tear through bar easily.
 
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CraigStu

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75 yrs old and I needed to cut my first rebar maybe 6 months ago. I have a metal cutting bandsaw, a recip saw w/ metal cutting blades and even a grit coated blade for my sabre saw. None cut rebar. I think maybe the correct grit type blade might work but the sabre saw is too small for the job. I actually ruined a band saw blade before I figured that out. I now cut rebar w/ an abrasive wheel in an air die grinder.
 
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Burl

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As a union ironworker when i was a young man, this problem presented itself a few times. An acetelyne torch will melt the rebar enough to drill the hole, though watch out for popping concrete.
 
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chad215

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Caldwell,tx
I said I'd reply with results- well of course after I bought the rebar cutting bit I didn't hit any other rebar. So still no idea how well that bit works. Below is what I'm starting to build working in the evenings here and there. I'm ready for rafters at this point.
 

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chad215

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Single slope covered area for a hot tub. High side is ~10'. Trying to do all of this by myself is not as much fun as it used to be.
 
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jonesg

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strutaeng said:
Yeah, that's just a standard bit. Sometimes you can drill through if you catch the rebar off center. You probably hit it right in center.

They make spacial rebar cutters for this. Switch to the rebar cutter when the regular bit starts bouncing, then switch back once you drilled through the rebar. Some of my THD have them in stock now.

Edit: https://www.homedepot.com/p/Milwaukee-3-4-in-x-12-in-SDS-Plus-Rebar-Cutter-48-20-6799/320278633
Click to expand...
looks like an end mill... with a long shank.
 
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