Unroll merged surface

Hi guys! New here, so please excuse me if i violate protocol somehow.

I am having an issue with the “unroll developable surface” command I have 2 identical surfaces. One of the surfaces is a polysurface, and the other has been merged into a single surface. When I unroll both of them, the merged surface comes out shorter than the polysurface. the unrolled polysurface is correct when I do the math. Why is the merged surface unrolling at a different length?

Thanks in advance!

Welcome here!
You are likely to get better answers if you also provide the 3dm file with your question. That will eliminate a lot of speculation.

Thanks for the heads up! I have attached the .3dm file (not sure how to attach it to the entire thread)Unroll surf.3dm (88.1 KB)
Let me know if I did this correctly.

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The two surfaces unrolled with identical areas to the original surfaces for me. Unroll surf DC01.3dm (175.9 KB)

I am using Rhino 4.0 SR-9…and cant open the file you provided. Could that have something to do with my problem as well?

I used Rhino V6, and the file was saved in Rhino V6 format which can’t be opened by earlier versions. Here is a version saved in Rhino V4 format. Unroll surf DC01 V4.3dm (166.7 KB)

I also tried unrolling the surfaces in V5 and the results were identical to V6.

My vague recollection is UnrollSrf may have been updated for V5.

Can you upload a file with your unrolled surfaces?

Unroll surf - with surfaces.3dm (163.0 KB)

so here it is, please let me know what you think. This problem is driving me crazy

Nothing obvious to me. As I previously mentioned my recollection is UnrollSrf may have been modified and improved for V5 compared to V4. V5 was released circa 2012.

Yep, as David mentions - UnrollSrf was significantly overhauled for V5…


Is it safe to say that I will continue to have this problem until I upgrade my software?

At least it’s safe to say that the command will continue to work the same until you upgrade