SolidWorks Sheet Modeling Question

In Part 5 of my series on KOMPAS-3D, I modeled a die in sheet metal. I know that there is no way you can actually press that die. The die was part of what I call “fun modeling” – basically, creating wild stuff without bothering whether it can be manufactured or not. Hey, I am a C++ programmer and enjoy testing the limits of CAD software. Designing algorithms is what I do best, not parts and assemblies. And while doing so, who knows, I may stumble upon something interesting.

As it turns out, I think I did. While I was modeling the die in KOMPAS-3D I was trying to do the same in SolidWorks so that I could compare the two. SolidWorks did not allow me to create a zero length edge bend. I mean SolidWorks needs the sheet to run some distance after it takes the turn. Even a distance of 0.0001 would do, but not zero. Take a look at this image.

Click image for larger view

Notice the distance of 2.0001 mm. If I change that to 2.0, the bend fails. I guess 0.0001 is the tolerance for distance. KOMPAS-3D didn’t have this limitation. It allowed me to specify a length of zero. So did Alibre Design. Its not that the sheet cannot be pressed. I think it can. So why does SolidWorks not allow it?

Which also begs the question: where would you use a zero length edge bend? Frankly, I don’t know. I write C++ code, remember, not model sheet metal. Moreover, if zero length edge bends are such a bad thing, then why does KOMPAS-3D and Alibre Design allow them?

I just checked and found that like SolidWorks, Inventor also does not allow zero length edge bends. So this is all getting very interesting to me. Although I must admit that this is more of academic interest than anything else. Whether SolidWorks allows zero length edge bends or no does not really affect my day job. But to some of you, it may. If it does, do leave a comment. Have you ever found the need to do such a thing? Is there a technical/manufacturing reason why such an edge bend should not be allowed? Please enlighten me.

And by the way, if something like this is bothering you, you may want to put it across to the Stump The Chumps team at SolidWorks World. Here is my submission.

  • I'm not an expert on this either, but I know that you can't bend this kind of bends on a normal bending machine. It will skit or deform.

  • I was thinking more like stamping.

  • Stamping deforms the material, the length calculations wouldn't be right then. But I don't know if this is big enough that it matters?

  • No, I don't think this is that big a deal. This is more of academic interest. I am simply wondering why some MCAD systems allow it and some don't. Nobody is going to lose sleep over this issue.

  • Couldn't it be that they wanted to prevent false length calculations? I guess using 0.0001 isn't really preventing it but then the user knows he cheated.

  • Possible. Its like extruding a sketch to a distance of 0.0001 mm. SolidWorks allows that as well. But then you know that the designer isn't thinking straight.