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Unbending a roll bar to find the Bend deduction


New member
I would like to know of a way to unbend a roll bar to find the exact length of a pipe.

I know I could just measure the centerline of the pipe and calculate it out, but I would like to know if I could do this automatically either in sheetmetal or another way.



View attachment 93


New member
I would create a datum curve and sweep the protrusion along the datum curve. You could then use INSERT>DATUM>EVALUATE to capture the curve length. If you have used several curves to sweep along, you can create a composite datum curve and use the Evaluate feature to capture the composite curve length.

I have never attempted to create a round bar in sheetmetal and unbend it.


If you were to somehow find a way to bend a tube such that the material along the geometric centerline of the part experienced zero deformation, then donha's message would give you exactly what you need. Unfortunately, this is not possible.

Finding the straight length of a bent tube such as this is generally an empirical thing... even more than with sheetmetal forming. Unless you know from experience the relationship of straight length to bent length for your exact process, you'd just be guessing by taking any number that Pro/E gives you.

Here is another thread on this topic:



New member

I don't believe this is possible in Pro/Sheetmetal because you have a complex bend, there is distortion to the metal. You can draw it but you can't generate a developed length from the model as you can with simple bends. donha suggestion will get you close but this one has to be empirically derived.



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