How will I know if I hit rebar?

[600SL]

I just tried to drill 6 holes into my concrete floor and of course on the very last hole the dill bit won't go down more than 3/4". There are no sparks and putting a steel wire down the hole does not appear to attract but the magnetism is week at the end of the wire. I am wondering if I hit rebar. Theoretically the rebar should be 2.5" down. The hole before it was also very difficult to drill and I thought it may be the bit but the bit drills some of the other holes deeper without any issues. Could there be a super hard roc in the mix?

 

[The Cobbler]

carbide still in good shape on the bit?

 

[ADSR]

If you keep going, the bit will 'roll off' and make a new way.

 

[Jlbc212]

If the bit is okay, then, yes, it could be a very hard rock. What diameter hole are you drilling? Maybe you could try a smaller diameter bit and/or try applying more pressure.

 

[ADSR]

Maybe you could try a smaller diameter bit and/or try applying more pressure.

No, don't do this. Then the next size bit will not want to drill it out, it will hammer into the hole and wreck the drill.

Ask me how i know

 

[readhead]

We run into this everyday. We have rebar eaters in all sizes. You will probably have to go to a concrete supply house to buy them.

 

[Dart53]

Readhead has the right idea: rebar eaters. Construction supply house will have them.

 

[Modern Jess]

I learned something new today. Thanks, guys!

 

[600SL]

Thanks for all the replies. I already started out with a small bit ~ 3/16". I like to use a pilot hole as it keeps the bits from walking. Plan is to go to 3/8. Got 5 holes drilled about 3" down and the last one ~ 3/4". Its hard to tell if a carbide hammer drill bit is sharp they all look dull to me after the first use but the tip is not chipped.

Even if I get it drilled out I will be reluctant to use a Tapcon screw as it may break off in there.

 

[600SL]

We run into this everyday. We have rebar eaters in all sizes. You will probably have to go to a concrete supply house to buy them.

OK sounds good but how do I know if I actually hit rebar and bot just super hard rock.

What is the likely hood of hitting rebar at 3/4" in a 6" slab.

Then comes the next question. If there is rebar there or super hard rock would it be suitable for a Tapcon screw ounce it was drilled.

 

[Chaznsc]

Put a small magnet in the hole and see if it grabs.....

 

[toplessHO]

if you hit rebar you should see some bits of iron on the end of the bit
It will magnetize the filings so they should stick

 

[stokefire7]

Whats the drill are you using ?

 

[marinusdees]

If you hit a hard rock, a hard hit on a punch will shatter it and you can continue the hole.

 

[stokefire7]

Better yet what bit ?

 

[srmofo]

OK sounds good but how do I know if I actually hit rebar and bot just super hard rock.

What is the likely hood of hitting rebar at 3/4" in a 6" slab.

Then comes the next question. If there is rebar there or super hard rock would it be suitable for a Tapcon screw ounce it was drilled.

I will say it usually gets pushed down from the concrete guys walking on it and being too lazy to pull it up so the likely hood should be low, but you never know

 

[600SL]

The drill is a Milwaukee 3/8" hammer drill. The bit is a carbide tipped Tapcon Masonry bit and I will be installing Tapcon screws.

http://www.tapcon.com/products

 

[stokefire7]

I'd say your bits dull and your drill is rated for masonry. Just a guess though. You'll be able to see the rebar.

 

[MScott]

I had a similar problem when I was rebuilding a house for my daughter. l had to drill about a hundred holes for tapcon screws to attach drycore to the basement floor. It was old concrete and probably made with granite stone rather than the limestone that is mostly used now. I was finding that the drill bit supplied with the tapcon screws was only lasting for about 4 or 5 holes before they wouldn't drill any more even though I was using a hammer drill. I tried more expensive bits (Bosch) but they didn't last much longer. I was eventually advised to use a Bosch SDS rotary hammer drill. That was the answer. I was able to drill the rest of the needed holes with only a couple of bits. Apparently the stone in the old concrete was so hard that it just wore out the bits but the SDS rotary drill was able to go right through them. You can rent the drill at HD or similar.

 

[600SL]

Wow

Thanks for the replies everyone. After reading all the replies it seemed like it was just very hard rock. It took about 1/2 hour but I pushed through it and once through the drill just cut right through the next inch.

I believe it was a combination of both hard rock and a worn bit. When I went with the final size 3/8 bit, I had very little problem.

 

[CharlesLloyd]

This thread helped me ascertain that, as 600SL experienced, I was hitting hard rock and not rebar. So I thought I'd add my solution. For me, drilling my three holes in concrete is a one-time activity, so I couldn't just justify more tools/time. I used a $20 HarborFreight hammer drill and a TapCon bit. This drill worked pretty well for two holes, but the third just couldn't go, so I am pretty sure the hammer action was working properly -- never used a hammer drill before, so my ignorance was not helping!

In the end, I happened to have a really small diamond coring bit (5/32) that was just long enough to cut through the problem aggregate so I could complete the hole with the TapCon masonry bit. I had tried for 10-15 minutes with the masonry bit without progress until I put the diamond coring bit in play (using water sprayed into the hole, hammer off), and about 2 minutes later, I got through the problem.

Amazingly, the entire set of 5 diamond bits only cost about $8 on Amazon. Search for:

Neiko 00823A 5-Piece Diamond Grit Hole Saw Set | 5/32” to 1/2”

https://www.amazon.com/gp/product/B00ODSS5NO/?tag=atomicindus08-20

 

[nes999]

This thread helped me ascertain that, as 600SL experienced, I was hitting hard rock and not rebar. So I thought I'd add my solution. For me, drilling my three holes in concrete is a one-time activity, so I couldn't just justify more tools/time. I used a $20 HarborFreight hammer drill and a TapCon bit. This drill worked pretty well for two holes, but the third just couldn't go, so I am pretty sure the hammer action was working properly -- never used a hammer drill before, so my ignorance was not helping!

In the end, I happened to have a really small diamond coring bit (5/32) that was just long enough to cut through the problem aggregate so I could complete the hole with the TapCon masonry bit. I had tried for 10-15 minutes with the masonry bit without progress until I put the diamond coring bit in play (using water sprayed into the hole, hammer off), and about 2 minutes later, I got through the problem.

Amazingly, the entire set of 5 diamond bits only cost about $8 on Amazon. Search for:

Neiko 00823A 5-Piece Diamond Grit Hole Saw Set | 5/32” to 1/2”

https://www.amazon.com/gp/product/B00ODSS5NO/?tag=atomicindus08-20

For that price I just bought a set to keep around!

Sent from my VS985 4G using Tapatalk

 

[cheechi]

For that price I just bought a set to keep around!

so on the one hand, new member brings up a 2 year old thread with a link to go buy something.

on the other hand link has no referral code or malicious redirect. And, for that price I just bought a set too. good reviews and a ton of them, has to be at least an ok tool.

should the moral of the story be 'if you're going to shill this is the right way' ? would make things interesting if the scam/spam posts went to legit products. Could still be pretty effective SEO though. maybe we're suckers for buying them?

 

[nes999]

so on the one hand, new member brings up a 2 year old thread with a link to go buy something.

on the other hand link has no referral code or malicious redirect. And, for that price I just bought a set too. good reviews and a ton of them, has to be at least an ok tool.

should the moral of the story be 'if you're going to shill this is the right way' ? would make things interesting if the scam/spam posts went to legit products. Could still be pretty effective SEO though. maybe we're suckers for buying them?

I use Nieko deburring tools, and am very happy with them. It is being sold from and shipped from amazon, which is always a good sign. Worst comes to worst it's 8 bucks, that's a cup of coffee to some people.

Sent from my VS985 4G using Tapatalk

 

[cheechi]

that was about 70% smartass. But it should give the mods some food for thought anyway.

Whether or not I need them I have enough concrete & block in my home they are worth having just in case. And I do appreciate the suggestion from Charles.

 

[Radix2]

Those grit bits are nice to have for fine work or tile drilling...

For this thread, I will throw out another product promotion. Give up on old fashioned hammer drills. Period.

Go buy a harbor freight SDS drill and some bits, it will work 100x better than any hammer drill and cost little.

Anyone on here should have a set.

 

[nes999]

Those grit bits are nice to have for fine work or tile drilling...

For this thread, I will throw out another product promotion. Give up on old fashioned hammer drills. Period.

Go buy a harbor freight SDS drill and some bits, it will work 100x better than any hammer drill and cost little.

Anyone on here should have a set.

I prefer to have both.

 

[MikeF2316]

Those grit bits are nice to have for fine work or tile drilling...

For this thread, I will throw out another product promotion. Give up on old fashioned hammer drills. Period.

Go buy a harbor freight SDS drill and some bits, it will work 100x better than any hammer drill and cost little.

Anyone on here should have a set.

I agree with this. What is a struggle with a hammer drill is a breeze with the SDS type rotary hammer

 

[rburke65]

I used a large Milwakee SDS drill when I installed my lift. Ate that concrete up!

 

[joes169]

Those grit bits are nice to have for fine work or tile drilling...

For this thread, I will throw out another product promotion. Give up on old fashioned hammer drills. Period.

Go buy a harbor freight SDS drill and some bits, it will work 100x better than any hammer drill and cost little.

Anyone on here should have a set.

I agree completely, and will add that the free black oxide bit that comes with Tapcons is barely worth what you paid for it. The first thing I do when we buy Tapcons is throw the bit out, they're terrible junk. Generally speaking, they would have to send 20+ bits to install the 75 Tapcons in the box that they accompany...........

 

[Radix2]

I agree with this. What is a struggle with a hammer drill is a breeze with the SDS type rotary hammer

I used a large Milwakee SDS drill when I installed my lift. Ate that concrete up!

I threw it out there because some people still do not know that there is a huge difference between a SDS style drill and the old masonry hammerdrill since the bits look alike. Now the SDS stuff has come down in price so far, no reason not to get some.

I will also put a rec out for the ryobi one+ SDS drill since many have that system.