# Keep constant length when folding

Question asked by Kevin Moreau on Jun 11, 2013
Latest reply on Jun 11, 2013 by Kevin Moreau

Hi,

I always have a hard time working with sheet metal, especially when it comes to mating components together.

But my issue right now is that I am trying to model a curved sheet metal that has an inside diameter of 180 feet and a thickness of 1,125 inches. I want the sheet metal to be 218.75 inches wide when it is unfolded. Here is how I procede:

1. sketch an ark that will be used to control the inside diameter of 180 feet

2. offset the arc outside by half the thickness to get the neutral axis. (which should always have the same length since it is neither in compression nor in tension)

3. give an arc dimension to the neutral axis of 218.75 inches

4. convert all the lines but the inside diamter to construction lines and then use the sheet metal function with a thickness of 1.125 and the desired heigth.

I attached a file where you can see my problem. The neutral axis is 218.75 inches when folded but when I unfold the sheet metal, the width becomes 218.734375 inches.

How can I unfold the sheet metal so that the neutral axis keeps the same length?

Thank you

Kevin