How to Measure Length of Bent Object

Take a piece of string, run along length of bent object, mark or cut at end, lay string out straight, measure, done.

No, that's too easy. He needs an excuse to go to the hardware store and buy a new, expensive tool.

thank you kramarat for your response - sounds good.

But, I'm working with tight tolerance of +/- .005". Does anyone know if there is any kind of formula I can use given angle, thickness, and bend radius. I don't know if I can hold tolerance with string.

Anyone?

Missing details needed to give a great answer but if it is something smaller than say ones hand an optical comparator or a cmm are possibilities for measuring.

http://www.toolingu.com/definition-350110-1996-optical-comparator.html

Milo

(Pasting from my reply to the dupe thread):

For the bend part, pi x radius x angle(°) ÷ 180.
For the straight parts, their individual lengths.
Add them all up.

That's how to calculate it. To measure it, use a tape.

That sounds too easy. I guess measuring it before it was bent is out of the question, also.

I wonder if there's some kind of medical software where he could take an x ray and get an exact calculation of length. That or find somebody with one of these:

http://www.melsensor.de/laser-scanner-en/m2-ilan2-100hz-en.html

"Radius, angle of bend and thickness of object is given."

Given to whom?

Is this sheet metal, pipe/tube, other structural shape(s), or what; and what material?

After the item is bent, it will spring back about 2-3°, so the inside radius will not perfectly conform to the die nose, shoe, mandrel, or whatever.

One way to go about this is to measure a prototype carefully before and after, and then adjust the real goodie accordingly.

"Using calipers" seems to indicate that this is a smallish item.

What is the purpose of the exercise?

If this is a bent pipe or rod - what about put the smallish object on a scale and divide by the weight per unit length of the class of pipe / rod used? (and reproduce and test the part.)

The problem with your question is that not enough information is provided. Consider the bent rod in the sketch below. Which of the 5 lengths shown, A through E, is the one you wish to measure? Each one will give you a different value. Or is there yet a different length you are interested in? A picture of what you are trying to measure would be helpful.