drilling concrete

MF294-4

Member
I need to put a hole in some concrete that is 18 inches thick and I keep hitting rebar. What kind of bit do I need or what do you do when this happens?
 
I chipped the concrete away from the rebar enough to allow me to get a Sawsall blade in position, then cut the rebar out with the Sawsall.
 
MSC sells a rebar cutter drill bit made by Relton. The bits come 3/8 inch up to 2 1/2 inch. My catalog is a few years old but the 3/8 sold for $47.47 and the price went up to $202.00 for the 2 1/2 inch. If there are a lot of holes to drill one of these may be worth it. From 7/8 up, there are replacement heads. The hole is drilled with a conventional hammer drill bit until the rebar is encountered, then the rebar cutter is used to cut the rebar, then back to the hammer drill bit.
 
A good bit will eventually go through it. If the hole is large enough to get a torch head in then I would use that. Or as mentioned a sawzall can work too. In the past I had to core 5" holes through 26"concrete with rebar and we used these techniques even though a better way would have been to hire someone with the better tools and have it done in half the time.
 
You can rent a true core drill at a good rental center. They vacuum themselves to the floor and drill through anything. they need a garden hose to flush away the cut concrete and do take some time. Used to sell the bits many years ago. They charge you by the hour or day and measure the wear on the bit.
 
As has been stated, rebar cutter bit would be your best bet. You may also be able to strike an arc with a welder on the rebar and blow the puddle away with the oxygen from an oxy/ acetylene setup. This method is usually only effective at shallow depths though. Another method is to put metal shavings in the hole and continue drilling. This method is surprisingly effective.
 
To you and Jason the Red: What kind of shavings? Long swarf from drilling, small cut pieces, powder from a hacksaw or what? Steel, copper or aluminum, does it make a difference? Do you fill the hole with it or just surround the drill tip?
 

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