Unfold or flatten surface?

gaëtan_bussy

Hello,
I made a skateboard design in onshape.
The skateboard will be made by seven sheets of wood. I want to cut those sheets by laser.
To be precise, we have to flatten the surface. I tried the FS "fold" (unfold) but this FS made only a projection and not a realy unfold or flatten function.
How can we do a real unfold function in a surface?
Thanks!
PS the project: https://cad.onshape.com/documents/e6ce8a9d2d64fc49dd2d8727/w/3b7be7a9979035a1a31f1dfa/e/66b7d6dfbea81de149d87b97

Jake_Rosenfeld

@konstantin_shiriazdanov has a good set of custom features for questions like this.

emagdalenaC2i

And you can try with ExactFlat in the App Store https://appstore.onshape.com/apps/Manufacturing/3RPIJMNQJ2SXMC7IZEUELB23XF3VEXVAAKM4UUA=/description

gaëtan_bussy

Jake_Rosenfeld said:

@konstantin_shiriazdanov has a good set of custom features for questions like this.

Thanks! I already made a test with the "fold" FS (found here: https://cad.onshape.com/documents/0bb13c1b6ed6d4a6dd75cf99/w/b4493d47a45c27ce485c84b9/e/c8050a35a7417c12b801bd40)
But I only managed to made a simple projection...

emagdalenaC2C said:

And you can try with ExactFlat in the App Store https://appstore.onshape.com/apps/Manufacturing/3RPIJMNQJ2SXMC7IZEUELB23XF3VEXVAAKM4UUA=/description

Thanks! Yes I already made one test. It's quite good! I had some problems with the unities in the file exported. I have to make more tests.

But if the solution is not in an external module, it would be great! I want to orgenise workshop about creating skateboard with young people... the simplest would be the best!
And this is not a long term free solution...

konstantin_shiriazdanov

Fold FS was made to work with curve/face transforms defined by the surface with constant cross section, i.e it will make distorsions for surfaces with double curvature. Sorry.

gaëtan_bussy

Don't be sorry! And by the way, thank you for the great custom features you wrote!!!

So... I have to find something else...!

chris_8

This has worked for me in a similar situation: needing a flat pattern for use in a laser machine. Installing, learning new app, dealing with exports/ imports, then vice versa took a while.  But the price was great.

https://extensions.sketchup.com/en/content/flatten-faces

7Cs

My situation is the same, but its not a Skateboard, it is a flatten botton, chined sailboat hull. Exact Flat could be used for this situation?

S1mon

There are a number of CAD tools that can do various levels of flattening. Exact Flat seems to be one of the more powerful albeit stand alone.

Rhino also has a decent flatten command. You can get a 90-day free trial.

matthew_stacy

In my opinion, with respect to compound curved surfaces (such as the skateboard example at the beginning of this thread), any "flattening" algorithm must be taken with a grain of salt.  The transform from curved to flat is non-determinant, meaning that there is no single solution.  If an application such as Exact-Flat generates a flat pattern for this skateboard blank, the best case scenario is that we will have to trim the perimeter of the finished board after pressing.  Worst case ... the finished part is too small ... or buckles and won't conform to the press plates.

There are potentially many solutions, depending on detailed material properties and the exact tooling used to manufacture the part.  The waters may be further muddied for a manufacturing process like progressive-die stamping where the blank often include material margins for fixturing purposes (that aren't cut off until the final hit).  Closed- die or open-die?  How will the work-piece be held?

In the CAD "sheet metal" realm, software limitations essentially restrict us to simple straight line bends governed by the concept of a "neutral axis", thickness, bend-radius, and k-factor.  The underlying premise is that material thickness is uniform and remains constant throughout the manufacturing process.  Occasionally we cheat a little bit with relatively simple formed-features such as dimples and louvers.  These simple rules cough up hair balls when applied to compound-curved surfaces (even something as simple as a salad bowl).

jelte_steur814

there's a feature script called "unfold" that may be useful: 

thanks Pascoe!

https://cad.onshape.com/documents/8b05b9839aba12bb8ccb2b7e/v/09003b9bc2cb1ae185dd2aa4/e/dda6fda206e5409a01f69cee?showReturnToWorkspaceLink=true

MichaelPascoe

@jelte_steur814 no problem! That document is a barely modified copy of Onshape's official standard documentation here:
https://cad.onshape.com/documents/12312312345abcabcabcdeff/w/a855e4161c814f2e9ab3698a/e/5e639eb1b1834188ae46203a