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Thread: scrapyards

  1. #21
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    Aug 2012
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    Warwickshire, UK
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    Quote Originally Posted by BCRider View Post
    But all re-bar is ribbed. That's how it locks into the concrete. Or did you see some smooth bar stock in that pile?

    Years ago (45 and more) high tensile re-bar was all that we could buy around here. But somewhere along the way things changed to some lower garbage grade as it was "good enough". The old high tensile stuff was hell to machine. If using HSS it needed a very slow cutting speed and coolant to avoid work hardening and taking the end off an HSS cutter in the blink of an eye. Much like some stainless alloys. If you can find proper high tensile that may still be the case.

    Some cheap junk that I had to use turned out to be more or less mild steel. But as mentioned above it had some bad inclusions in it that. On top of that it was gummy to the cutter and the surface was galled badly even when I tried using cutting oil. I was only turning this junk because someone needed a threaded end on a few pieces to cast into some concrete and he didn't have time to go and get "J" bolts. And for some reason that escapes me at the moment the obvious idea of some all thread rod bent into "J's" wasn't good enough.

    By all means try a piece or two if it's cheap. But don't be surprised if you find it's total junk.
    No, all rebar isn't ribbed. When I was actively involved (in the UK and Ireland), mild steel was smooth, high tensile was ribbed. Obviously, mild steel had a lower tensile strength, but the bond strength it developed with concrete was enough even for a smooth bar. I seem to recall that the lap length required was greater for mild steel because of the smooth finish.
    The ribbing on high yield enabled the bond to be developed in a reasonable lap length.
    Plain mild steel and ribbed high yield meant there was no chance of confusing the 2 out on site.

    Looking carefully at the photo, I thought the smaller dia bars looked smooth, but I might be wrong about that.
    'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

  2. #22
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    Feb 2010
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    Hampstead, NC
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    I've made the mistake of trying to turn rear and it was total garbage. It welded fine for me and welding is one recommended way to join it.

    Sent from my Pixel 2 using Tapatalk

  3. #23
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    May 2002
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    Auckland, New Zealand
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    How can rebar be called rubbish? Isn't it a vital part of a structure e.g. bridge piling, building foundations? In NZ there has been a big stink recently with untested (false certificates) mesh and (I think) rebar being sold and used...it must meet standards or it is not suitable.

    That doesn't mean it will machine nicely though.

    I guess mesh is just used for crack control on your driveway, but the rebar I see going into bridge piles and high rise structures is incredible. Rubbish? I doubt it.

  4. #24
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    Nov 2006
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    durban s africa
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    I remember watching a tv programme where an entire high rize building in Vegas was condemmed because the contractor was using a torch to cut the re bar. The engineer on his rounds asked why they had a torch onsite and when they innocently replied it was for cutting rebar he condemned the entire building . Ouch.

  5. #25
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    Nov 2008
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    You have to watch those contractors. I was on a job where we were installing several hundred equipment cabinets in a 4th floor room that was recently added to a 3 story building. The floor had been recently poured and was reinforced with rebar. We had to anchor each cabinet with 7 expanding anchors that were around 4 inches deep. We caught the contractor using a diamond hole saw to drill the holes for the anchors. When questioned about it, he said it was because they were hitting rebar with damn near every hole and it was breaking drills.

    Can you imagine what happens when you condemn a 4 story telephone company equipment building?
    Measure twice. Cut once. Weld. Repeat.
    ( Welding solves many problems.)

  6. #26
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    Aug 2012
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    Warwickshire, UK
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    Quote Originally Posted by plunger View Post
    I remember watching a tv programme where an entire high rize building in Vegas was condemmed because the contractor was using a torch to cut the re bar. The engineer on his rounds asked why they had a torch onsite and when they innocently replied it was for cutting rebar he condemned the entire building . Ouch.
    There must be more to it than that. Cutting rebar with a torch isn't best practice, but you certainly wouldn't condemn an entire building because of flame cut bar ends. I bet he'd think differently if he instructed a late change in rebar already fixed and the choice was spend 2 days dismantling and rebuilding the cage, or spend 10 minutes with a torch cutting bar ends. Normally ends are sheared/cropped in the bending yard, but if you need to 'adjust' out on site, its a disc cutter usually, though I have used a torch in confined spaces where we couldn't work with a disc cutter.

    What is a no-no is heating up bars especially high yield in order to bend them in situ when things won't fit.

    This is getting off the subject though. We mostly seem to be in agreement that rebar is rubbish for machining.
    'It may not always be the best policy to do what is best technically, but those responsible for policy can never form a right judgement without knowledge of what is right technically' - 'Dutch' Kindelberger

  7. #27
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    Dec 2016
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    Helsinki, Finland, Europe
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    Quote Originally Posted by Richard P Wilson View Post
    There must be more to it than that. Cutting rebar with a torch isn't best practice, but you certainly wouldn't condemn an entire building because of flame cut bar ends. I bet he'd think differently if he instructed a late change in rebar already fixed and the choice was spend 2 days dismantling and rebuilding the cage, or spend 10 minutes with a torch cutting bar ends. Normally ends are sheared/cropped in the bending yard, but if you need to 'adjust' out on site, its a disc cutter usually, though I have used a torch in confined spaces where we couldn't work with a disc cutter.

    What is a no-no is heating up bars especially high yield in order to bend them in situ when things won't fit.

    This is getting off the subject though. We mostly seem to be in agreement that rebar is rubbish for machining.
    It seems like torch cutting itself had nothing to do with it, cutting torch was just a hint that something wrong is going on.
    http://www.gr-us.com/%E2%80%9Chorror...80%9D-for-mgm/

  8. #28
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    Jun 2013
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    Lancaster County PA
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    Quote Originally Posted by MattiJ View Post
    It seems like torch cutting itself had nothing to do with it, cutting torch was just a hint that something wrong is going on.
    http://www.gr-us.com/%E2%80%9Chorror...80%9D-for-mgm/
    Wow, thanks for the link, I had never heard anything in the news about that building. There had to be several levels of incompetence or graft or both for the building construction to go that far before being brought to light.
    I'm amazed.

    Dwight

  9. #29
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    Oct 2010
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    Auckland New Zealand
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    Well I’m surprised cutting rebar heating and bending with oxy Acet if it was high tensile rebar would make it brittle but cutting to length wouldn’t affect it as the heat affected zone would be at the bitter end of the rebar where it would have little or no affect on the strength There has to be more to this story


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  10. #30
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    Nov 2006
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    durban s africa
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    Quote Originally Posted by Kiwi View Post
    Well I’m surprised cutting rebar heating and bending with oxy Acet if it was high tensile rebar would make it brittle but cutting to length wouldn’t affect it as the heat affected zone would be at the bitter end of the rebar where it would have little or no affect on the strength There has to be more to this story


    Sent from my iPhone using Tapatalk
    I agree.

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