Can I use an acetylene torch instead?

[Phutman]

I have a furniture project that requires two 3 foot long pieces of rebar to be heated pounded/textured and bent into perfect half circles. I don’t have a forge (I know, I should fix that), but I do have an acetylene torch. Do you think I could accomplish the even bending portion of the task by just heating the rod with the torch?

[Frosty]

You can but rebar can be kind of iffy stock. Does it have to be rebar? If not you can use the appropriate size round or square hot rolled "mild" steel and an old BBQ for texturing. You can bend the 1/2 circles cold easily enough. 

What is the radius of the arcs? If they're matched I turn full circles then cut them, they come out as matched halves.

What texture are you looking for? Does the rebar texture play a part?

Frosty The Lucky.

[George N. M.]

As Frosty said, yes, you can use any heat source to get the metal soft enough to bend, forge, torch, bonfire, etc..  It's just that the gases for a torch can get expensive.  

For making segments of a circle I have found it easiest to use a mandrel.  That is something already the same diameter as your desired final size and then bending the metal around the outside of that, e.g. a car wheel, a piece of pipe, an oil drum, etc..  If you are not using a mandrel always hit the metal from the inside between 2 support points.

"By hammer and hand all arts do stand."

[JHCC]

You say "two 3 foot long pieces of rebar to be [...] bent into perfect half circles". That would make the radius of each half-circle just under 9-1/2". That's entirely manageable with an oxyfuel torch and a mandrel of the proper ~19" diameter: just clamp one end of the bar to the mandrel and work your way down its length by heating a few inches at a time, bending to match the curve, and repeating.

You don't say what diameter rebar you plan to use, but you might be able to bend a thinner piece cold. Hot or cold, I would strongly recommend making yourself one of these beasties, which I learned about in Otto Schmirler's "Werk und Werkzeug des Kunschmeids" ("The Blacksmith's Craft and Tools"), which follows George's recommendation to "always hit the metal from the inside between 2 support points" and is great for making long bends:

Finally, do all your texturing before you make the bends.

[Scott NC]

  A rosebud would certainly come in useful for thicker size rebar.  Actually for smaller sizes too, as you can heat longer sections, and keep them red hot easily and get more uniformity.

[Latticino]

59 minutes ago, JHCC said:

That would make the radius of each half-circle just under 9-1/2".

Think we have a different interpretation of the OP design.  I see this as a half-circle will be bent with a perimeter totaling 3'.  Therefore the full circle would have a 6' perimeter.  6' is 72", divided by pi I get a diameter of 22.9".  This should be a radius of approximately 11.5" at the centroid of the bend.  Perhaps you calculated an allowance for the thickness of the rebar?  How did you know what that would be?

[JHCC]

No, you're right; I multiplied when I should have divided and forgot to convert feet to inches. I need more coffee.

I stand by my tooling recommendations, though.

[George N. M.]

I have found that unless the stock you are bending is very thin compared to the radius of the bend it is better to add 50% of the thickness of the metal being bent to the radius.  So, if I was bending a 1" bar around a 10" mandrel in a complete circle I would calculate the length needed based on an 11" circle (10"+ 2[1/2"]).  Also, it is always easier to use a bit longer piece and cut off the excess than to come up short.

In my example of a 10" circle vs an 11" the difference is 3.41" of stock needed which is a significant gap to make up.

"By hammer and hand all arts do stand."

[Gazz]

I think you would find it slow and laborious to bend them with an acetylene torch, an oxy/acetylene torch on the other had would work but as mentioned, both would be expensive.  You don't say what the diameter of the rebar is, ie. 1/2', 5/8" etc.  Those sizes could be bent cold using the the methods described above and a large hammer or with a solidly mounted bending fork and a piece of pipe for leverage.  Lots of small bends over the whole piece until the desired radius is acheived.  Not sure what texture you are looking to get though and that is another issue.

[Scott NC]

  Just clamp it down, heat it up with a torch as you go and bend it around a form of some sort of the right size.    Buy an extra long piece and over wrap it and cut off the excess.  Small rebar could probably flex a bit for some leeway.  Expensive?....