# Modeling challenge ~ Wrap 180° to 192° - How to accomplish this offset

I have an ongoing project with a complexly modeled surface. It is basically a tapered cylinder with lots of features. Endeavoring to create a die such that I need to maintain the feature dimensions and reduce the diameter of the non-developable surface. I must map 180° of the cylinder to a new surface that is smaller in radius and 192° edge to edge. per the image
The depth of all the existing feature geometry is less than 10% of the radius of the existing surface.
I have tried bend but that does not seem to get me where I need to go. Any Ideas?
TIA
Robb

are these arcs? if so:

use `Length` command to get the length of the original…
to get the new radius, it’s Length / Angle (in radians)…

for example… if the original surface has an arc length of 50 units and your desired angle is 193 (or 3.368 radians)

50 / 3.368 = 14.85

so your radius will be 14.85 units.

if this does what you need, it could be scripted pretty easily if you need to do it more than a couple of times.

or in grasshopper, something like:
arcangle.gh (8.0 KB)

Thanks for that Jeff.

My original is a highly detailed polysurface with lots of 3D features. It is 1/2 of a tapered cylindrical solid with many exact features. The issue is that I need to translate 180³ of this solid to 192° of a smaller radius solid with the features dimensionally intact and proportionally arrayed.

I’m beginning to think that I should maintain my feature bits (separately) that I boolean subtract from the base solid to get to my inital solid. Then I can potentially reuse and Flow them from 180° of the original surface to 192° of the new surface. There are some features that I would need to Flow (rigid=no) so they conform to the new surface better.

Thanks for the Grasshopper for the curves. I’m guessing that will be useful for this project - just not this case.

Robb

that was just the basis for figuring out the new radius upon changing the arc angle while maintaining arc length.

a bit more controls added in this grasshopper:

arcangle2.gh (17.8 KB)

with that one, you can control the size of the 1/2 cone, change the angle for the new cone, change how the surface is divided up…
the divisions will remain proportional upon changing the angle to 192º

the points signify where the components should be placed (this could be automated as well.)

idk, if i’m understanding you correctly, i’d probably stay away from using `Flow` for this.