Unbending in CAD

[Ian Johnson]

I would like to make the base of this by bending acrylic over a jig.

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How would you go about straightening it in CAD to create a drawing for the piece that will be bent? It is made by sweeping along a spline. It's not a perfect circle or ellipse, so it's not a simple calculation of circumference. I'm using Onshape, but I also have Alibre and would be willing to learn Fusion or Creo if they happen to have features that would help. If illustrator can do something like that it would be a possibility, maybe by tracing or importing a dxf. It is just a long rectangle of known width with rounded ends and a hole at each end. I just need to know the length from end to end. It's easy enough in real life with a sewing tape measure, but I don't know the CAD equivalent.

[Rich Harman]

I wouldn't think that it was terribly important to get the length exactly correct for something like that. Treat it as a semi-circle and make a test piece.

If the design is in CAD now you should be able to select one of the edges and get its length. Or, create a new sketch with the original in the background to trace on. Easy to do is Fusion 360 - you just project the geometry. Doesn't lay it flat but allows you to determine the length required so that you can draw a new piece.

Another roundabout way is to measure the surface area of a face. If you know the area and the width, then you can calculate the length.

[Chris DeGerolamo]

In AutoCAD, I would view the thing from either side, and use FLATTEN OR FLATSHOT to generate the 2D version (i.e. polyline) of the bracket. From that, list the entity to get length, then take that and subtract (2*R).

You may need to offset 1/2 of overall thickness depending on your material(s).

[Doug Griffith]

You mentioned Illustrator. In that App I'd import the file as a DXF as viewed from the front (so you're looking at the "U" shape). Then I'd use the getpathlength script floating around the interweb to get the length of the curve. From there, redraw the shape as needed.

[Dave Sheldrake]

Unrollsurface in any 3D decent package to generate a flat version of the actual curved surface