I'm going to get out my new bender that's been in the box on the shelf for
years now. I used to have one made by Breakdown Industries. It's just one
of the common ones with the dies that mounts on a stand.

When figuring the bends, and doing so as not to make three incorrect copies
while arriving at one acceptable one, how does one calculate the amount that
any given piece of metal will "grow" during the bend, so you can cut stock,
make the bend, then have it come out right.

Or do you just make it, then cut the excess off, or stretch it if short?

Is there a guide of this kind on line? Also, figuring out and marking where
to start the bends, and in general things that can help me rather than the
old trial and error method, particularly at today's steel prices.

TIA

Steve

In article ,
says...

I'm going to get out my new bender that's been in the box on the shelf for
years now. I used to have one made by Breakdown Industries. It's just one
of the common ones with the dies that mounts on a stand.

When figuring the bends, and doing so as not to make three incorrect copies
while arriving at one acceptable one, how does one calculate the amount that
any given piece of metal will "grow" during the bend, so you can cut stock,
make the bend, then have it come out right.

Or do you just make it, then cut the excess off, or stretch it if short?

Is there a guide of this kind on line? Also, figuring out and marking where
to start the bends, and in general things that can help me rather than the
old trial and error method, particularly at today's steel prices.

TIA

Steve

Machinery's Handbook, find "Bend Allowance" in the index and then look
it up to determine for specific material, radius, and thickness.

Terry mentioned the bend allowance tables. But.....

It's helpful to look at how the metal behaves; A couple of things: First
is that the neutral line is pretty close to the center of the material:
the outer edge gets stretched (and thinner), the inner edge gets
compressed (and fatter). So if you you do a half inch radius on 1/4"
stock, the material in the bend will see a 5/8" radius.

The other ugly part is the springback. Some springback will always be
the not all the metal is stretched beyond the yield point, any that
is not is in the elastic range and you will get springback. You can
minimize springback by making sure your dies are adjust to put all the
bending action at a single point. If you have any gap at the point of
bend, you will have more springback.

I did quoting for various bent tubing parts. It was always safer to bend
first and do trims as a second op. Ditto for any holes. Drilling might
be easier on flat stock but getting the holes in the right spot was
always dicey that way.

Steve B wrote:
I'm going to get out my new bender that's been in the box on the shelf for
years now. I used to have one made by Breakdown Industries. It's just one
of the common ones with the dies that mounts on a stand.

When figuring the bends, and doing so as not to make three incorrect copies
while arriving at one acceptable one, how does one calculate the amount that
any given piece of metal will "grow" during the bend, so you can cut stock,
make the bend, then have it come out right.

Or do you just make it, then cut the excess off, or stretch it if short?

Is there a guide of this kind on line? Also, figuring out and marking where
to start the bends, and in general things that can help me rather than the
old trial and error method, particularly at today's steel prices.

TIA

Steve

"Steve B" wrote in message
...
I'm going to get out my new bender that's been in the box on the shelf for
years now. I used to have one made by Breakdown Industries. It's just
one of the common ones with the dies that mounts on a stand.

When figuring the bends, and doing so as not to make three incorrect
copies while arriving at one acceptable one, how does one calculate the
amount that any given piece of metal will "grow" during the bend, so you
can cut stock, make the bend, then have it come out right.

Or do you just make it, then cut the excess off, or stretch it if short?

Is there a guide of this kind on line? Also, figuring out and marking
where to start the bends, and in general things that can help me rather
than the old trial and error method, particularly at today's steel prices.

TIA

Steve

Draw the piece, label the bends in order and on which side, bend thin pieces
of stock to dial it in. Measure everything possible in the brake, and cut
off after the bend if practical.