Drilling #8 Rebar

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Drilling #8 Rebar

Post by noworries » Wed Apr 01, 2020 6:15 pm

Hi all, new here and I want to basically hollow out a 5 inch long piece of #8 rebar....should I even attempt this on a drill press??

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Re: Drilling #8 Rebar

Post by Glenn Brooks » Wed Apr 01, 2020 6:33 pm

no worries,

Hiya, welcome to the forum!

Interesting question! Perhaps you can gives us a little more info about what you want to do. What diameter hole in the rebar? How accurate/concentric needs to be the hole?

What other tools or materials do you have available.

It’s generally feasible to drill rebar, with an extended shank drill bit. However, ID, clamping capability, and drill press size are all limiting factors. It would be a lot easier to drill and ream to size on a lathe... for example.

So post a bit more info and we can help.

Just flaying away at it often works also! :)

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Re: Drilling #8 Rebar

Post by noworries » Wed Apr 01, 2020 6:53 pm

I guess I could have been a bit more informative... I have an old 16 speed 15" 3/4 hp drill press. It needs to be a blind hole, 7/8 dia as close to dead center as possible. The only lathe I have access to is a 12 in wood lathe. After seeing it in writing I am not real sure it is possible While I could likely get one done...I need 12 so I may be in the market for a new machine.

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Re: Drilling #8 Rebar

Post by warmstrong1955 » Wed Apr 01, 2020 8:26 pm

Have you measured the actual diameter of the bar you have? 1” in nominal, but what is the actual diameter below the ridges?

As it is, Saying the ‘minor’ diameter is actually 1”, you are going to be leaving a 1/16” per side, so you will have to be centered, straight, and drill straight. So a good vise, or a good fixture would be required. Like Glenn said, a lathe would be the tool of choice.

One other thing with rebar, is sometimes made out of all sorts of scrap metal these days. Much comes from China. It may be the normal grade 40, mostly, but it may have some harder places in it too. Or sand. I’ve seen some with the hexnuts in them.....obviously not long enough in the furnace.
I’ve unloaded bundles off flats, and had some break. I’ve also Cross-drilled holes in it to use it for grade stakes, and sometimes hit a spot where I had to move over a bit to get a hole through after sharpening the bit.

Just a couple thoughts.
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Re: Drilling #8 Rebar

Post by RMinMN » Thu Apr 02, 2020 4:48 am

Does the job you have actually require rebar? There may better solutions. Give us some hints on what it needs to do.

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Re: Drilling #8 Rebar

Post by ChipMaker4130 » Sat Apr 04, 2020 7:24 pm

Drilling a 7/8 hole in rebar is an exercise in frustration. I would attempt it with a carbide spade drill, but not a typical twist drill. Its a small piece, why not make it out of CRS and if you need the rough exterior go after it with an angle grinder. Even with the grinding, you'll probably be quicker and more successful.

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