Sorry if the title doesn't make sense, I just cant think of how to word it so I'm going to be using images to help.

Basically I have a piece of sheet metal that I have bent along one edge to give me a right angle, I then bend it down the middle, perpendicular to the previous bend, at 35 degrees, now I have already cut out a relief to account for this bend forcing my metal on the right angle into itself, but when I make the second bend, the length of one of the previously bent pieces has to be shortened to make the tip of its edge line up with the other edge.

The side profile of my sheet metal part

A better angle to show the part

The edges I'm talking about are the two right angle bends that are separated by a small relief, this relief allows the main bend of 35 degrees take place.

The flat pattern part

But as can be seen in the flat pattern, I have had to trim the edge of the sheet in one place to allow the bent piece to appear more uniform, if I left the edge untrimmed and the same length along its entirety, when bent, there would be an overhang.

So obviously there would be more or less overhang depending on the angle of the main bend, so my question is what is the relation/equation between the amount needed to be trimmed and the angle perpendicular to that face?

Is it to do with making the length of the hypotenuse match the width of the other piece? The lengths would be the same if I cut a relief out of both sides at an equal angle but maybe there are situations where that isn't viable?

Some numbers that might be helpful, the width of the right angle bend on the lower half is 12mm, the width of the trimmed piece is 9.5mm, this width gets me close to inline but it isn't perfect.

  • $\begingroup$ It depends on your bend radius and material parameters. But why dont you just relate it in the bent state if all you care about is the cad app. $\endgroup$
    – joojaa
    Jan 19 at 16:37
  • $\begingroup$ Make sure you leave enough clearance in that relief for it to spring back during the bending process! $\endgroup$ Jan 19 at 21:47
  • $\begingroup$ the diagonal part is as long as the straight part it meets measured from the center for the bend $\endgroup$
    – Jasen
    Jan 20 at 10:25

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