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Flat Pattern A Twisted Part

Message 1 of 13
1901 Views, 12 Replies

Flat Pattern A Twisted Part



I was recommended Meshmixer by a friend of the business to try and flat pattern a sheet metal part that inventor cannot deal with. The only problem is i haven't got a clue how to use it.


The part i'm trying to flatten is 2.5mm thick, 2400mm Long and twists 90 Degrees over 2000mm.


Below is a screenshot of the part


and attached is the Inventor IPT file.


any help would be appreciated


Message 2 of 13

Do you want it 100% flattened with no twist? There are many different ways depending on what you want done. ('Soft transform' most likely)


If all you need is flat rectangle though, why not just remake it in inventor to your desired dimensions, but without the twist?


You have attached in incompatible file type (.ipt) I'm not sure how yours was able to load into MM, but could you send an .stl file?

Message 3 of 13

Think you're looking for EDIT/Unwrap.


I tried to reconstruct your object to show the workflow:

  1. Run EDIT/GenerateFaceGroups and pull its AngleTresholld slider to get a single color (= group) for each side of your twisted sheet.Ohne Titel.jpeg
  2. Go to SELECT and double click one side to select it.Ohne Titel 2.jpeg
  3. Hit Y to separate itOhne Titel 3.jpeg
  4. RUN EDIT/Unwrap and AcceptOhne Titel 4.jpeg
  5. You now might export that flattened shape as a .svg via File menu.

Gunter Weber
Triangle Artisan

Message 4 of 13

I've tried to follow your instructions and when i get to the unwrap im not getting the same result,


attached is the issue im getting,


any advice would be appreciated.



Message 5 of 13

Hmm, seems you didn't define the face groups properly... so you did get that many open boundaries (blue lines)

Can you post your original file in a zipped mesh version (obj or stl)? I'll look into it.

Gunter Weber
Triangle Artisan

Message 6 of 13

here is the STL file,


thank you for the help

Message 7 of 13

Ya that mesh didn't export properly from inventor, lots of  open boundaries. 'Inspector' isn't fixing them, 'make solid' also not working. Same with 'close crack' or even 'remesh'.


And the issue seems to reappear after generating face groups. Strange,

Message 8 of 13

I'm no Inventor user so I can't give you decent advice on how to export a mesh from there properly.

A common mistake exporting meshes (especially in STL) from a CAD applications is that partial surfaces/bodies aren't joined properly to a single object before exporting it. 


Now your STL comes with all those cracks. Actually these aren't Cracks (in MM terms) but some vertices are displaced (but nearby). Repairing  this automatically is beyond MM's repair abilities. You might do it manually using the zipper SCULPT brush.... but that's a lot of work. I used Meshlab and its Filters>CleaningAndRepairing>MergeCloseVertices (Meshlab merges 505 vertices). After that step the result loads without cracks in MM.

Next issue is the uneven density of its tessellation and some self intersecting faces. I solved that doing  Remesh and Smooth.

Now Unwrap works as expected.

I attach a .mix file containing the repaired version of your source file, an extracted surface and its Unwrap result.

(Unit seems to be cm) 

Gunter Weber
Triangle Artisan

Message 9 of 13
in reply to: MagWeb

I like helping out where I can on this forum, kinda like a little problem solving brain teaser every now and again, since I at least have some base knowledge in MM. But you always prove your mastery of all triangle related works. I still have so much to learn!

Message 10 of 13
in reply to: MagWeb

MM newby - has worked with one smaller file,

I am following the directions, Unwrap is ignoring me.  Up to that part it looks as if it is behaving.  Had some crashes fiddling with stuff I was trying.


Something amiss with the surface stl or file part size?

Message 11 of 13
in reply to: davebYYPCU

Your problem results from low poly uneven meshing. You can show/hide the wireframe hitting W.

Unwrap needs more vertices at the boundary (especially at the lower part > red arrows).

To fix that:

  • Hit Ctrl+A (Cmd+A on Mac) to SelectAll
  • Run Edit/Remesh on the selection. Rise Density to max and set BoundaryMode to RefinedBoundary
  • Accept and run EDIT/Unwrap


Gunter Weber
Triangle Artisan

Message 12 of 13
in reply to: MagWeb

Thank you, worked 2nd time round.

Message 13 of 13

can someone please make a flat pattern of this for a paper cut out it doesn't have to be super detailed

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