I've got some 3/8" un-deformed reinforcement rod to bend in a 7"
radius bending in 180 degrees until the rod is running parallel to
itself. I only need 6 of them as part of a sculpture I am doing. I
thought I would get a 7" diameter piece of pipe maybe with a flange
and weld a post along the pipe, heat the rod, insert the rod between
the post and pipe and bend until the desired bend is achieved. The
bends need to be reasonably duplicated. I haven't gone to the junk
yard yet, so I don't know what my chances of finding the right piece
of pipe are going to be right now. The recycle center (aka junk yard)
where I go has a lot car and truck wheel parts, rotors, pipes, rails,
and other classic steel junk. Is there is better way to do this? Maybe
a better choice of assembly parts to build the jig?
-Mike

"mlcorson" wrote in message
oups.com...
I've got some 3/8" un-deformed reinforcement rod to bend in a 7"
radius bending in 180 degrees until the rod is running parallel to
itself. I only need 6 of them as part of a sculpture I am doing. I
thought I would get a 7" diameter piece of pipe maybe with a flange
and weld a post along the pipe, heat the rod, insert the rod between
the post and pipe and bend until the desired bend is achieved. The
bends need to be reasonably duplicated. I haven't gone to the junk
yard yet, so I don't know what my chances of finding the right piece
of pipe are going to be right now. The recycle center (aka junk yard)
where I go has a lot car and truck wheel parts, rotors, pipes, rails,
and other classic steel junk. Is there is better way to do this? Maybe
a better choice of assembly parts to build the jig?
-Mike

It sounds like a 14" rim from a car would work well for a bending jig.(Or
13" to allow for springback) Or did you mean 7" diameter? I weld a small
tab to hold one end of the rod fixed and use a pipe the rod will slip inside
of to form the bend- advancing the pipe as the bend is formed. I have a vice
mounted on a pipe outside my shop to clamp the rim in.
Steve

In article .com,
"mlcorson" wrote:

I've got some 3/8" un-deformed reinforcement rod to bend in a 7"
radius bending in 180 degrees until the rod is running parallel to
itself. I only need 6 of them as part of a sculpture I am doing. I
thought I would get a 7" diameter piece of pipe maybe with a flange
and weld a post along the pipe, heat the rod, insert the rod between
the post and pipe and bend until the desired bend is achieved. The
bends need to be reasonably duplicated.

Have you considered a simple bending fork? Two bolts in a vise, or two
bolts welded to a long handle. Given the scrollwork that can be done
with those, a simple 180 should not be too difficult to pull off, with
perhaps a couple of practice pieces first, in addition to the 6 more you
need.

How did you bend the first one?

I certainly found that bending 1/2" deformed rebar freehand, with no
special attempt to constrain the bends (function, not esthetics)
resulted in bends that were all of pretty similar radius (all bent cold,
with simple leverage). I bent 90 degree pieces for my corners, and 180
degree hooks at the ends of straight bars. I can't see that you need
heat if you actually mean 3/8" bar.

Then again, you could wander into the tool rental and get a rebar bender
for an hour or two. Those have rolls to constrain the bend to a
particular radius.

--
Cats, coffee, chocolate...vices to live by

3/8 th inch rebar? I would just bend it cold. You mention both 7 inch
radius and 7 inch diameter, so I am not sure which you mean. But pick
something somewhat smaller as there will be some springback.
Maybe slip a 1/2 inch pipe about three or four feet long over the rebar
so it bends where you want it to bend yet you have a long lever arm.
The piece you bend it around obviously needs to be securely anchored.

Dan

Are you willing to spend fifty bux? Harbor Freight has a small Hossfeld
type bender that would do the job easily. Speaking from experience, I would
just eyeball the bends, using the first one as a pattern for the others.
You can do six in less time than it would take to set up a jig, with the
trial and error to eliminate the springback error.

For a metals sculptor, having a small bender will be an asset for all future
projects.

mlcorson wrote:
I've got some 3/8" un-deformed reinforcement rod to bend in a 7"
radius bending in 180 degrees until the rod is running parallel to
itself. I only need 6 of them as part of a sculpture I am doing. I
thought I would get a 7" diameter piece of pipe maybe with a flange
and weld a post along the pipe, heat the rod, insert the rod between
the post and pipe and bend until the desired bend is achieved. The
bends need to be reasonably duplicated. I haven't gone to the junk
yard yet, so I don't know what my chances of finding the right piece
of pipe are going to be right now. The recycle center (aka junk yard)
where I go has a lot car and truck wheel parts, rotors, pipes, rails,
and other classic steel junk. Is there is better way to do this? Maybe
a better choice of assembly parts to build the jig?
-Mike

A piece of 2x or plywood, jigsaw or bandsaw cut to the proper radius,
would suffice as a die. Screw a block to the back side of the die to
allow clamping in a vise. Attach a stop (L-bracket maybe) on the die top
to hold the rebar in starting position to begin the bend.

To further explain: The bend should be a 1/2 circle with a diameter 7"
across. measuring across the rods when they are paralell. Leo, the HF
bender would not give me a large enough bend. Using the maximum 3" size
die would give me a an aprox 3" diameter bend. Correct?
-Mike

I think the HF bender would accept a die big enough to do what you
want to do. I don't have a HF bender, just one I cobbled up. But
don't think you need one for just six pieces.

Dan

"mlcorson" wrote: (clip) Leo, the HF bender would not give me a large
enough bend. Using the maximum 3" size die would give me a an aprox 3"
diameter bend. Correct?
^^^^^^^^^^^^^^^^^
I was not suggesting using the included dies with the bender to form the 7"
semicircle. I am suggesting that you feed the rebar through the bender,
making little pulls on the handle to form an arc. Then feed it through
again, making more little pulls to close the bend. It will not be
difficult to make a 7" semicircle in the middle of a piece of rebar, with
straight legs 7" apart. You may have a little trouble getting both legs the
same length without practice. If this is important, you could cut the legs
afterward to the desired length.

Another way to use the bender would be to use it to make a circular die to
form the 7" semicircle. That would involve trial and error to get the right
diameter for the die, and probably wouldn't be worth it for only six pieces.