Making Tight Bends with Heavy Gage Wire

[rgsparber]

I was inspired by the wire bending tool from "DIY Useful Ideas". His tool makes the bending of thick wire almost effortless. Due to the forces involved, the pins used to bend the wire have to be rather large in diameter. That also sets the radius of the bend. I thought it would be fun to figure out how to reduce this radius without reducing the diameter of the wire. A working model is presented but I invite readers to suggest refinements before I commit to the finished design.

If you are interested, please see

https://rick.sparber.org/WireBender.pdf

Your comments are welcome. All of us are smarter than any one of us.


Thanks,

Rick

[DIYer]

Thanks rgsparber! We've added your Wire Bender to our Metalworking category,
as well as to your builder page: rgsparber's Homemade Tools. Your receipt:

Wire Bender by rgsparber

tags: bending

[mbshop]

First thing that came to mind while reading this was that both ends of the pins would have to be secured to prevent yhe pins from bending. Had to do this looooong ago. Forgot about it till you brought this up.

[CanBeDone]

Your comments are welcome. All of us are smarter than any one of us.

There are two items I am missing in your design: It is not adjustable, and it doesn't have a fence.
For a once-off job, being adjustable is, of course, not a issue. And if you are planning to bend several items, without a fence repeatability will be poor.
This is what I learned after building this
following a suggestion found on this forum a few weeks ago, a three pin design very much like your own. Since I had to bend flat bar 6x32mm, instead of the pins I used pieces of 20mm plate, held in place by M10 bolts. The angle plate on the left is adjustable, and that is where my design failed: the three M10 bolts are not capable of holding the angle in place, and thus the bend is not as sharp and neat as I wanted it. Even though the high-tensile bolts have been tightened until the 20mm plate got (locally) deformed, the friction forces they do apply are not high enough, and slippage does occur - and thus the bend is no longer sharp.

There is a solution, however, as exampled by tuomas Vise bending attachment: Instead of three pins use two vises, joined by a hinge. When closed loosely, these vises ought to give just the control over pin spacing that I need to give me the sharp bend that I want.
For the vises, I will follow closely this design, used here on a rotating table: . Essentially, a M12 grubscrew has been grooved such that a 3mm roll pin connects it to the moving jaw, without blocking its ability to rotate freely.

My fence is just an afterthought; it works just as well as any more fancy machining could have given me.

[rgsparber]

There are two items I am missing in your design: It is not adjustable, and it doesn't have a fence.
For a once-off job, being adjustable is, of course, not a issue. And if you are planning to bend several items, without a fence repeatability will be poor.
This is what I learned after building this
following a suggestion found on this forum a few weeks ago, a three pin design very much like your own. Since I had to bend flat bar 6x32mm, instead of the pins I used pieces of 20mm plate, held in place by M10 bolts. The angle plate on the left is adjustable, and that is where my design failed: the three M10 bolts are not capable of holding the angle in place, and thus the bend is not as sharp and neat as I wanted it. Even though the high-tensile bolts have been tightened until the 20mm plate got (locally) deformed, the friction forces they do apply are not high enough, and slippage does occur - and thus the bend is no longer sharp.

There is a solution, however, as exampled by tuomas Vise bending attachment: Instead of three pins use two vises, joined by a hinge. When closed loosely, these vises ought to give just the control over pin spacing that I need to give me the sharp bend that I want.
For the vises, I will follow closely this design, used here on a rotating table: . Essentially, a M12 grubscrew has been grooved such that a 3mm roll pin connects it to the moving jaw, without blocking its ability to rotate freely.

My fence is just an afterthought; it works just as well as any more fancy machining could have given me.

CanBeDone,

Thanks for sharing your experience! So far, I have been just playing around with the tool so had not considered problems related to repeatability. I have figured out the correct place to set the wire so the bend occurs where I want it so that is related to repeatability. If I understand your setup correctly involving two vises, I think it poses a problem for me. Say I want to bend this 7 gage wire every 1/4". I can see how the first bend would work with two vises but can't figure out how to do subsequent bends. Can you say more about how the two vises work?

Thanks,

Rick

[rgsparber]

First thing that came to mind while reading this was that both ends of the pins would have to be secured to prevent the pins from bending. Had to do this looooong ago. Forgot about it till you brought this up.

Mbshop,

Yup, the pins do bend a little but since the wire is near the base of each pin, it isn't bad enough to prevent good, sharp bends.

Rick

[CanBeDone]

CanBeDone,

Thanks for sharing your experience! So far, I have been just playing around with the tool so had not considered problems related to repeatability. I have figured out the correct place to set the wire so the bend occurs where I want it so that is related to repeatability. If I understand your setup correctly involving two vises, I think it poses a problem for me. Say I want to bend this 7 gage wire every 1/4". I can see how the first bend would work with two vises but can't figure out how to do subsequent bends. Can you say more about how the two vises work?

Thanks,

Rick

To give you a quick answer: No, my two-vise design won't work for bending distances that short. For such short distances I would use the techniques developed for bending chain links, such as

or, to stay at home,
Wire Bender
Re-think on wire bender for making chain links

My two-vise bender has been designed with just a single bend in mind, as this is all I need. Without too much effort, it can be re-designed for bends spaced at least 16mm (5/8") apart. That is the limit imposed by the M12 grub screw I use to move the movable jaw forward and backward. Changing that to something smaller would reduce permissible clamping stress to such a degree that I no longer would trust the vise not to break during use.
If you look at any of the above links, all of them bypass the vise strength issue by bending around a former, custom made for the bending job on hand. This former replaces two of the three pins in a bender, which makes the whole device stronger and sturdier, allowing 180 degree bends, more than the 90 degrees you have contemplated in your design, and I have in mine. The dimensions of the third pin can be chosen for strength, they are not determined by desired bend spacing, as this pin will always be on the outside of the bend.

To satisfy your curiosity regarding my tow-vise design, here it is

before bending and after making a 90 degree bend:

The green block is where the whole contraption is mounted in a bench vise, the gray and purple part is movable on a vertical axis, not visible here. The vertical axis was chosen so that the piece-to-be-bent can just be dropped into the contraption, without fastening any screws. The purple round bar on the right hand side of the first drawing accepts a 20mm (3/4") water pipe as a bending lever, not shown in the drawing. The part-to-be-bent is shown in red, resting against a silver fence on the left.

My device so far does not have a fence to pre-set the bending angle, for that I still am looking for a good idea. Anybody out there with an idea that is truly rugged, as the bending forces I need to apply are substantial? (My 10 ton press cannot deliver the needed forces!)

Here is a look at the bending axis design, the green hinge-bearing block being outlined just as a wire frame.

Three small screws hold a substantial washer against the 24mm diameter shaft of the hinge, so that there is no play. The shaft itself is press-fitted / glued into the movable (grey) vise.

And here is a look at the internals of the moving jaw of the vise.

Downward forces are supplied by a T-nut (grey) and M4 screw, horizontal forces by a 3mm rolling pin resting inside a groove cut into the M12 grub screw. The pin is strong enough to withstand jaw opening forces, the 6mm diameter cylinder left after cutting the groove must sustain all the jaw closing forces, which means that the hole accepting the M12 grub screw needs to be flat-bottomed.

I hope this helps

[rgsparber]

Superb explanation and renderings! Lots of food for thought.

Thanks,

Rick

[Beserkleyboy]

Great idea and presentation. What drawing program are you using? Thanks very much
Jim

[rgsparber]

Great idea and presentation. What drawing program are you using? Thanks very much
Jim

Jim,

I use Alibre PE for 3D renderings and TurboCAD for 2D. It took me over 150 hours to master Alibre well enough for my needs. I also feed Alibre into CamBam to generate G-Code which then goes into Centroid software to control my CNC mill. Works well for me when machining 2 1/2 D.

Rick