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I have some 1-1/4" rebar that I would like to bend a couple of 90s at the ends so I can weld them together into an arch but I'm not sure if it will even be possible with what I have, a gas 1 burner forge, a coal fired barrel forge and a 1-1/4" hand EMT bender. I also have a large OA setup. My concern is that I won't be able to heat enough length, or keep it heated long enough length to make a smooth radius. My other option is to find someone with a hydraulic bender and pay them to do it, or just give the idea up altogether and make the arch square. Anyone have suggestions? What about making a long narrow temporary coal forge in the dirt or from fire brick in order to heat enough length?

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You don't need to heat more than a few inches at a time. For me it is easier to make a nice curve incrementally.

I wouldn't bother with the emt bender, instead make a jig with a pipe or solid round slice. Weld a stop 

Start your bend with either forge but finish it with the torch, easing the heat ahead while allowing the already bent part to cool, so it stays put.  A large hammer is very helpful. 

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draw your arch / radius on a plate weld tabs FB or angle to  that plate then use that Jig / tool to hot bend  what you need to do ! then heat some bend some heat some more bend some more use a bending fork make one mine is adjustable 

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What Latticino showed plus this clamped in your vice. This is being made.

Some hints for this set of tools. Make the opening slightly larger than the steel size. In your case, make it slightly wider than 1-1/4".

The angle cuts are needed. They allow you to get into tighter curves. It's more important for smaller scrolls.

For the anvil tool, I make each end a different size.

Grader blade is great material for these tools.

I make these sets for different size stock. 

Take a long heat and make small bends for good control.

2016-09-06 11.55.44.JPG

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Trench forges also work.  One old smith told me a tale from the 1930's when a fellow wanted to arch some light I beam for a structure and so built a long trench forge in a field and set the beam in it and fired it up. When it was hot; he picked up each cold end and walked it over to the peg he had calculated and installed previously and let it cool.  He knew it would sag in use and put the correct allowance of arc into it so is "sagged dead straight".

The controlling factor is that 1.25" is LARGE Stock!  Do you have equipment to handle it?  An Acorn table would be nice as would a 6" post vise, jib crane, sober friends, etc.

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As Thomas noted, you will need some proper equipment to bend such heavy stock.  What radius bend are you trying to achieve?  I keep an assortment of iron and steel wheels for bending forms which can be clamped to my heavy steel table and I bend around them.  Your oxy/acet torch may be sufficient for heat if you have the proper rosebud tip but for general heating like that I use oxy/propane with an appropriate rosebud.  You could also just bend them in the vise, hot that is, if you are not concerned with the radius.  Realize that it will take some muscle to make these bends so sober friends might be handy as again noted above.   I found this video on youtube that approximates the method I'm talking about;

 

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I was thinking it was probably  a large arc for a gateway.  If so you may want to make a bending jig that has a section of the curve the length you can heat it and then bend it in sections using the jig.  Going back over it with a rosebud can allow for smoothing if there are any offsets.

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One important thing to remember when tweaking any curve, and you will, is that you will have to tweak in two places for each fix. One to open/ close the flatspot and another opposite(close/open) tweak to compensate for the first tweak. 

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My original plan was a complete arch to suspend an O2 cylinder bell but also considering less than that, so that it is somewhat pointed at the top like a church window (see pic), which would be easier and might look better. I do have a heavy steel table that I can attach various jigs to, I also have a receiver hitch mount for my 6" vise so I can use a truck for stability if I need to. I have a thick piece of plate 36" diameter that I will weld the finished structure to, then drill the plate and bolt it to a concrete foundation in the ground. I am thinking about blowing some holes in the plate for the 1-1/4" rebar legs to sit in before welding for more strength.

 

church window.JPG

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Have access to bare ground hard pan? If so you can drive stakes to match the inside of your arch. Heat the stock and using your vehicle pull it over the stake/jig. 

Rig chain attachment points at the ends and a bag or two of charcoal briquettes will heat it enough. If you have a 4x4 pickup truck and load it heavy for traction you can probably arch it cold in low range. You'll want spotter who knows how to stay clear of potential slipped or broken chain shrapnel to give you guidance.

Once you have your arch then it's a simple matter of heating the center and bending it into a Gothic arch. 

Practice with wire first so you don't end up with an "interesting" sculpture instead of what you wish to make.

Bending over a die this way is old school for bending pipe. Thread a cable through a length of pipe, line it up on a stump and apply pullage with a bull dozer to both ends of the cable is an old logger technique. Makes nice smooth bends without crimping the inside of the radius as that's where all the bending force is applied.

Frosty The Lucky.

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Not enough undeveloped space on my city lot for all that. What I really wish is that this Covid didn't happen and I could take my steel to one of the open forges and get guidance, there were always a bunch of experienced people willing to help. They've all been canceled though, until this horrible mess is over. I'll probably end up waiting a bit right now as we are expecting record heat the rest of the week.

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For a bend like that I would first bend a piece of 1/4"x1" to the radius you want and weld that on edge to your heavy table.  Heat your rebar in the forge, hopefully your forge can allow material to  pass through so you can heat the entire section that needs to bend.  When its hot take it to your welded 1/4" and clamp securely at the apex of the bend and then muscle the rebar around the form using good heavy duty c-clamps every 6" or so (clamp to the 1/4") to keep the rebar tight against the form.  The clamps are important to keep the rebar from bowing away from the form.  Make sure you preset the clamps to the approximate opening while your piece is heating and again, good to have at least one sober helper available.

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Will you be punching the suspension hole?  If so do it first and make the jig to bolt on at that point and then pull the cold ends down and in against the jig.  A large wooden sledge---like a commander might help.  I would suggest having enough stock to do this several times as you learn what works with what you have.

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Railroad track is considerably more difficult to bend than 1.25” rebar!  During the civil war saboteurs heated railroad tracks in bonfires and bent them around trees... so that they couldn’t be reused!  It would certainly be possible to make the type of bends you want by using a trench fire.  I suspect that you could coax such bends at black heats far short of red hot!  You might even try cold bending them!  To cold bend use a sledge and lots of strikes... similar to re-arching leaf springs.  A sort of giant bending fork setup on your steel table could also work for cold bending if you use long pieces so that you have good leverage... make lots of small bends... don’t try to get the whole arch at one go.

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17 hours ago, Frosty said:

stay clear of potential slipped or broken chain shrapnel to give you guidance.

A little trick i learned from ODOT, take a couple old towels (or new but dont let the wife know) or blanket, and wrap the chain in. A couple pieces of duct tape will secure it fine. If the chain breaks the shrapnel will be contained inside the towels and the towels will also dampen the chain enough to prevent it whipping around. 

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Thomas my plan is to weld the two pieces to a large coupling nut then thread in an eye. I don't have enough length to make it in 1 piece anyway so I need to use 2 pcs welded together.

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