Welding rebar and Nelson stud!
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  1. #1
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    Welding rebar and Nelson stud!

    tried to find some older post about it but nothing to answer my questions so here we go,
    these days im working with a lot of concrete stuff wich i have to do in the shop, just some bend rebars to weld on project just to make a small step or some bottom of garage doors, anyway, i've never had to work with rebar before and for the first time found the more harder to cut with a band saw and wierd to stick weld on mild steel, so the first thing came to my head was ''its probably a higher carbon material'' and search a little bit on internet and im right, those rebar are higher in carbon, so my questions is do i need to reduce the speed on the bandsaw (like stainless steel) and and what kind of welding rod and wire is requiere to weld it ? (or about what is the most common?)

    and my Nelson Stud question is those are cold rolled material?
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  2. #2
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    Re: Welding rebar and Nelson stud!

    I consider myself the KING of welding rebar. In fact, I'm picking up eight 7' length @ 1" thick rebar tomorrow. I'm making rifle target frames. Been making them for years.

    Anyway, I use a band saw or chop saw to cut rebar. For band saws, I use the slowest cutting speed on my machine. When it comes to welding, I use 6011 or 6013 with a lower than "middle" setting as suggested by the electrode mfr. Otherwise, the middle settings get too hot and burn up the rebar. When mig welding rebar, I just set my machine for about a 3/16" setting for welding and away I go. No problems.
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  3. #3
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    Re: Welding rebar and Nelson stud!

    Most of the rebar we cut we used the rebar cutter/bender that's basically a shear. You can certainly tell when the bar is hardened vs the "softer" stuff. If we didn't cut it with the shear, we cut it with the torch or the 14" abrasive blade on the gas saw.

    Never had a lot of luck with regular saw blades and rebar, though lately it seems the cheap stuff is softer than it used to be, and cuts easier with a saw. I can remember when we had to almost always use carbide hacksaw blades or an abrasive blade because it would destroy "normal" steel cutting blades.


    Note not all rebar is the same. The cheap stuff is usually remelt scrap and can be hard and soft in the same batch or even the same bar. Often it welds like cr@p no matter what you use. They make rebar that's specifically designed to be welded. Usually it's new stock and of a known alloy, usually of higher strength for midrise and highrise structures and infrastructure like bridges.. IIRC A-706 is the ASTM designation for at least one type of weldable rebar. AWS D1.4 covers welding rebar.


    ASTM A-615 rebar is usually not considered "weldable" IIRC.
    Last edited by DSW; 04-15-2012 at 11:43 PM.
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  4. #4
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    Re: Welding rebar and Nelson stud!

    I must add, there are different grades of rebar. There's grade 40 and grade 60 to name the two most commonly used. Grade 60 is 50% stronger than 40. I don't even consider grade 40 for my structural needs. In fact, if I recall correctly, they don't even make grade 40 rebar with #5 diameter size or smaller. Personally, I use #9 size (1 inch diameter) for my welding projects.

    I made a cool custom cattle gate out of 1" (#9) rebar for a friend at his glider airport. I never took a picture of it, otherwise I would have posted it. It was several years ago i made that gate.
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  5. #5
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    Re: Welding rebar and Nelson stud!

    I use my angle grinder with a zip disc or cut off disc to cut rebar.
    I use 7018 to weld rebar.
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  6. #6
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    Re: Welding rebar and Nelson stud!

    SuperArc, #9 bar is 1 1/8" not 1". Each number is the value of the bar in 1/8ths of an inch. #3 is 3/8", #4 is 1/2" and so on. #8 would be 1" rebar.
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    Re: Welding rebar and Nelson stud!

    Love the stuff
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  8. #8
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    Re: Welding rebar and Nelson stud!

    Quote Originally Posted by DSW View Post
    SuperArc, #9 bar is 1 1/8" not 1". Each number is the value of the bar in 1/8ths of an inch. #3 is 3/8", #4 is 1/2" and so on. #8 would be 1" rebar.
    You're right, I plain said that wrong! Thanks for the correction DSW.
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  9. #9
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    Re: Welding rebar and Nelson stud!

    If your wanting to do a proper code weld on rebar and its an unknown grade you need to pre heat to 500 deg and use an 80 series electrode. I have some repairs to do on #11 bars that were cut by a careless concrete saw operator next week. Needs beveled and going to use a 3/8" angle as a backing bar preheat to 500 deg and welding out as normal. going to use 1/8" 8018 in my case.

    Going to be another one of those fun jobs with to much oversight and procedure. YAY...



    As far as the nelson studs the proper way is to shoot them, but if they need to be affixed with welding then the proper way is to grind the little flux nugget on the bottom then weld out with a D1.8 rated electrode.
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  10. #10
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    Re: Welding rebar and Nelson stud!

    LayoutMan,
    what are you working on? pics would be great.
    Since you're in Canada, you probably get better rebar than us in the States.

    You too Dualie, I'd like to see a post about your repair. I know how sawcutters are, but blame the carpenters too, they're the ones who layout the cut lines usually. Kinda earie hearing post tension cables pop when cut
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  11. #11
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    Re: Welding rebar and Nelson stud!

    i find round stock including rebar cuts supereasy with a torch. get the tinyest little bit at the outer edge hot and bingo theres your cut...and 7018 has worked fine for me on rebar..

  12. #12
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    Re: Welding rebar and Nelson stud!

    thats nothing big, just some concrete stuff wich its a part a project that i have to do at my company, the things is when i do something that i don't do often, and where peoples at my job even if they have a lot of experiences don't know more about that and you still have probleme and people don't care about those rebars project because its always look like scrap and goes into concrete, so im just thinking ''there is probably a shop where they work a lot with those and have some inteligent way to work with'' thats why i post my thread!

    here some sketch of the project!

    the anchor things is 42'' long X 1'' 1/8 Dia steel Galvanized bolts and will recieve some columns when the concrete will be done, and the other sketch is just some lenght of 20' angles wich i have to fit those bend rebars at 12" c/c ±
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  13. #13
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    Re: Welding rebar and Nelson stud!

    What we used to do to set anchor bolts for columns was to make up a plywood jig with holes drilled where the bolts needed to go. Then we'd run a nut down the bolt leaving at least enough bolt above the nut taht needed to be out of the crete. Then slip the jig over the bolts and run down the 2nd set of nuts to lock everything in place. Many times we didn't even bother to wrap bar around the lower parts of the bolts, but wet set the entire assembly, leaving the nuts above the crete.

    If we needed to tie the bolts into bars per the drawing, we'd either weld short pieces to the bolts while held in the jig as shown. or get squares bent up to wrap around the units and tie them in place that way. If the guy with the bender was good, there wasn't a need to keep the jig in place, but most times we'd leave the jig on the guarantee the bolt spacing was correct.


    Some times the steel guy would give us steel plates with the holes already drilled in place to use instead of plywood jigs. Then we'd simply tack the anchor bolt to the plate below the crete and set the plate to top of concrete when we poured if we wet set, or tied them to height if we set them in advance.

    One nice thing about the jigs or steel plate is that you can mark out exact center on the plywood and use that to pull dimensions to locate the column. It's a lot easier than trying to back figure bolt spacing from column center lines.
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  14. #14
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    Re: Welding rebar and Nelson stud!

    thats funny because one older guy at my job told me to do (next time i have to do this) this same trick with a steel plate or plywood, but sometimes you have to do what the boos ask and when you have not a lot experience you can't say nothing or change anything, but for sure ill keep this in mind! so if i understood i can do only one plate like and guys at the field fix one set of anchor at the time or i ''normaly'' should have to make one jig for each set ? and have also to provide more nuts than needed if i want to tie the jig plate to put one nuts ech side of the plate ?

    thanks a lot for those extra explanations guys!!!!!!
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  15. #15
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    Re: Welding rebar and Nelson stud!

    Quote Originally Posted by DSW View Post
    SuperArc, #9 bar is 1 1/8" not 1". Each number is the value of the bar in 1/8ths of an inch. #3 is 3/8", #4 is 1/2" and so on. #8 would be 1" rebar.
    In case anyone wants to add a tad more knowledge to their brain tonight in case they didn't know, light bulbs are measured the same way. An R-30 is 30 eighths across or 3&3/4" (R is for reflector) a T-12 is 12 eighths or 1.5" (T is for tubular). A typical light bulb that most people used before CFs is the A-19.
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  16. #16
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    Re: Welding rebar and Nelson stud!

    Depends. On some jobs they give us one steel plate per column and they want top of plate to be top of concrete, and then they bolt the column on top of the plate. In some cases we have to do the plywood templates ourselves off one steel plate they give us. If I'm setting a bunch of anchor bolts all at the same time, especially if I'm wet setting them after we pour, it's usually easier to have templates for each one. If I'm tying them in to the rebar cages in advance, many times I can get away with only say 2, maybe 3 templates, enough to measure between columns for example. Once I tie them in place and everything checks, I can remove the template and use it to set the next set of bolts. In this case I'm usually using tie wire to make sure to tie them exactly in place to the sides of the form work as well as using the rods, or some times I'll tie the bolts to a 2x4 that's spanning the forms, to make sure things stay in place. I set the template over the 2x4 and then tie and screw everything together and remove the template.

    If I'm doing individual pours, such as light columns, where we might pour one or two with left over crete to run out a truck on a large pour, I only need maybe one or two templates, and I keep reusing them as needed.

    If you are going to weld the bars on, then you probably only need one jig. The guy sets the bolts in place and locks them down, then tosses the bars on the bolts and welds them on. When done he pulls off the template and uses it for the next one.

    As far as nuts, yes you'd have to have extras... sort of. In many cases the column guy will want to set a nut under each column and then nut on top. This allows them to use the lower nuts to plumb the column and adjust final height a small amount. The steel guys don't trust the footings to be close enough and give themselves a "fudge" they take up with the nuts. We come back in later and grout under the column bases with nonshrink and then pour the floor diamonds or saw cut the floor to column corners depending on the job.

    Even if they aren't going to use nuts under the columns, the cost of a few cheap nuts, offsets the labor to build a rebar frame like your original design. In many cases, we skip the rebar all together on the anchor bolts and the nuts simply keep everything in place. Note that if we do it this way we are using J bolts so there is resistance to uplift. We don't have to deal with seismic stuff where I live for the most part, and all the work is light commercial or residential not highrises.
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  17. #17
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    Re: Welding rebar and Nelson stud!

    I weld ALOT of rebar for the steel mills. And I perform a primitive destructive test throughout the batches. (see my threads, search chicken ladders)

    What has not worked was 6010/6011, 6013 & E71T-11 (Hobart 21B flux core).

    What does work is 7018 & ER70S-6 hardwire with either C25 or C100.
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  18. #18
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    Re: Welding rebar and Nelson stud!

    Quote Originally Posted by SuperArc View Post
    In fact, if I recall correctly, they don't even make grade 40 rebar with #5 diameter size or smaller. Personally, I use #9 size (1 inch diameter) for my welding projects.
    I use #3 & #4 grade 40 on a daily basis dealing with flatwork and foundations so it is definitely available. We use the 40 grade being the harder stuff is rough on our rebar cutters.

  19. #19
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    Re: Welding rebar and Nelson stud!

    Quote Originally Posted by ProCharger View Post
    I use #3 & #4 grade 40 on a daily basis dealing with flatwork and foundations so it is definitely available. We use the 40 grade being the harder stuff is rough on our rebar cutters.
    Yeah I don't know which rebar is used for the construction industry, I only know that I buy the grade 60 and use #7 and 8 all the time to make custom gun targets, a few gates and all sorts of lawn art stuff. Primarily I use it for the shooting stuff (steel plate frames, stems, etc.....)

    I've never used my band saws in it because I don't need precision cuts. I use plasma, chop saw or in a pinch, 225 amps and a 6011 rod to melt right through like a hot knife thru butter. I've heard that its hard and $$$$$$ on band saw blades.

    For the DIYer hobby welder, the stuff is just awesome. It's cheaper by the pound at my local metal retailer than buying flat bar for the hanging "legs" attached to steel target plates. For my sister in law, I made them a cool snow man outa the thin rebar (guessing it was size #4 or whatever 1/4" diameter would be).

    Again, I LOVE playing with the stuff.
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  20. #20
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    Re: Welding rebar and Nelson stud!

    Most engineers specify that it is not acceptable to weld rebar, at least not in structural applications in normal construction (foundations,frost walls, piers/columns) They require a minimum lap and ties. Most of the rebar commonly used isnt even considered weldable and is designed to meat a minimum strength requirement, along a stick it can vary quite a bit. You can tell pretty quick when cutting it with a shear, some cuts like butter and 4ft down the stick you hit a hard spot that almost cuts like bearing steel, it just splits and rings when the shear closes on it.

  21. #21
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    Re: Welding rebar and Nelson stud!

    Heres a couple of horrible cellphone pics of the repair of a small nick that was V'ed out and just partial pen welded with a 500 Deg preheat, some ESAB Atom arc 8018 142 amps on the old vantage 500.

    The second pic is the weed burner hooked to a industrial propane tank with an acetylene regulator set to about 20 PSI with custom stand off welded to it. You can see the angle iron backing used for the full pen welds. also note the 12GA sheet metal heat shield in front of a 1" piece of plywood and another layer of 12 GA as 4" away was a 12' tall storefront glass window i didnt want to buy. Also you can see the asphalt membrane burning around the columns that support the first floor of the 6 story building above it. The reason there was asphalt membrane is there was 2 stories of basement below.
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  22. #22
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    Re: Welding rebar and Nelson stud!

    Why the regulator on the LP tank? I use my weed torch from a 20# or 100# cylinder, without a regulator. I just, adjust the output knob to go from little to all out.
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  23. #23
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    Re: Welding rebar and Nelson stud!

    couldn't find the proper fitting to screw on to the tank with out the regulator. I was using a 20 lb tank.

    it had been a while since i used the weed burner and had to dig up all the parts again. Heck the gas hose was part of a shorty Oxy acetylene setup that i just pulled the oxy side off of.


    you know how things go with employees.
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  24. #24

    Re: Welding rebar and Nelson stud!

    There's grade 40 and grade 60 to name the two most commonly used.

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