Help with U-bolts needed

Suzuki4evr

Suzuki4evr

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Hallo guys.

I need some help on bending 90degr U-bolts and I want to know if there is a formula to use that can give the correct distance on where to bend the bolt to get the right distance between the legs. I will give some information and I will be using a simmilar bending tool as in the picture. All measurements is metric

Material: 14mm round 1043 Steel (EN8 bright)
Total length: 500mm
Radius of bends:6,5mm
Distance between legs:57mm
Screenshot_2021-02-10-09-59-55.png
The picture is just a sample of how my bending bar works.

The pin around which the bolt are bent is 13mm. What I basically want to know is how far from the center of the 57mm do I make the mark that must line up with the edge of the bending pin to actually get the 57mm distance between legs,because I am doing something wrong. That's why I figured there must be a formula of some kind.

If someone needs more information, I will try to give more.

Thanks for viewing.
Michael
 
The easiest way is to make a test bend after careful measurement and then apply the afterward carefully measured data on the real thing.
 
I have done this numerous times today with scrap metal rods,10mm,and I just stuffed it up every time. I must do something wrong, but I do not know what. I can't afford to waste the material for the job and time.
 
Yup, What @gonzo said.
Take a piece of rod, face off both ends to make it nice and square, and very accurately measure the length.
Now accurately mark the bar and make the bend at the mark. Now you can measure from the end of the bar to the inside or outside of the bend and subtract that from the distance you made the mark. This will give you the exact number that YOUR fixture needs to make your bend accuratly.

14mm is a pretty heavy bar to cold bend in a hand bender, especially when the bend radii is smaller than a material thickness, You may need heat to make the bend, the temp of the metal when you bend it will also impact the amount of material used in the bend. You will need to heat to a consistent temperature to get a consistent bend.

There are formulas that will get you close, The most common is to just calculate for the center line of the finished part. If you need accurate then you have to do the test coupon to qualify YOUR specific setup.
 
Generally speaking, the metal along the centerline doesn't distort so you would be looking at your inside dimension plus twice the radius or 57 + 14 = 71mm. Half that would be 35.5mm from center to center. This is a generalization and results may vary for a variety of reasons. To that end, I would do as Flyinfool suggests and mark the piece at the approximate midpoint of the bar and mark where you make the bend and measure from the ends of the bar to the marks. Make your bend and remeasure and you should be able to calculate a correction for the second bend. I would leave the bar slightly over length and cut the legs to final length after bending.
 
OK, just spitballing here ... I can imagine that inconsistent length results might well be due to the workpiece slipping (inconsistently) as it's bent. One possible solution - clamp a Kant-Twist on the workpiece, up against the right-hand post of the bender. That sould at least keep the bar from slipping while it's being bent.
 
I think that bends do not occur on the center line, due to differences in compressive strength and tensile strength, but I think that this can be calculated, but not by me. I think the term "normal line" defines it.
 
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