WB Sheet metal - perforation and unfolding

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Lars
Posts: 32
Joined: Sat May 05, 2018 10:39 am

WB Sheet metal - perforation and unfolding

Post by Lars »

<t>Dear fellow Freecad users, <br/>
We are preparing an item using the sheet metal WB, see attached. Some of the bends have cut outs and one of the perforations (two symbols made in a sketch attached to the sheet) fail to cut through the sheet. Unfortunately we do not understand the root cause for the error, and seek your advise.<br/>
<br/>
Secondly, the unfold functionality fails to unfold properly the item made from a series of bends, and your comments and input to the reason would be hightly appreciated.<br/>
<br/>
Sincerely<br/>
Lars<br/>
<br/>
OS: Windows 10<br/>
Word size of OS: 64-bit<br/>
Word size of FreeCAD: 64-bit<br/>
Version: 0.18.4 (GitTag)<br/>
Build type: Release<br/>
Branch: releases/FreeCAD-0-18<br/>
Hash: 980bf9060e28555fecd9e3462f68ca74007b70f8<br/>
Python version: 3.6.6<br/>
Qt version: 5.6.2<br/>
Coin version: 4.0.0a<br/>
OCC version: 7.3.0<br/>
Locale: English/UnitedKingdom (en_GB)</t>
Attachments
PURIX A50 PipeSupportStructure ver01c.FCStd
(281.04 KiB) Downloaded 30 times
Best regards

Lars
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papyblaise
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Re: WB Sheet metal - perforation and unfolding

Post by papyblaise »

It's a mess, I discovered 2 bugs:
it does not unfold the folds at 60 ° :mrgreen:
impossible to make other folds after making a Pocket :mrgreen:
Otherwise, when you make an extension, use the tool "Extend, do not make a fold at 0 °
Redraw "Simbole because it’s way too complicated, there are intersecting lines and it looks like there are cross constraints
draw it in at least 2 parts, 1 S then an Array, and a cross then a Polar Array
Attachments
unfold.PNG
unfold.PNG (9.16 KiB) Viewed 691 times
unfold.FCStd
(251.58 KiB) Downloaded 25 times
ulrich1a
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Re: WB Sheet metal - perforation and unfolding

Post by ulrich1a »

papyblaise wrote: Sun Jul 05, 2020 12:27 pm it does not unfold the folds at 60 °
I am using in the unfolder script a somewhat simple method to detect the end of a sheetmetal part. The detection method just looks if the vertexes of the face are laying in plane with the other side of the sheetmetal. The combination of this angle and the bending parameter seems to fulfill this condition. So a first workaround is to change the bending radius a little bit.

It looks like the unfolder needs an update.

Ulrich
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papyblaise
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Re: WB Sheet metal - perforation and unfolding

Post by papyblaise »

So a first workaround is to change the bending radius a little bit.
very large surprise : it's work
Attachments
unfold.FCStd
(386.75 KiB) Downloaded 26 times
unfold.PNG
unfold.PNG (8.23 KiB) Viewed 646 times
Lars
Posts: 32
Joined: Sat May 05, 2018 10:39 am

Re: WB Sheet metal - perforation and unfolding

Post by Lars »

changing the bending radius resolved the error when unfolding. Thank you for your support with this issue.

Only the issue related to cut out of the symbols remains. Symbols are contained in a sketch which is fully contained/defined. When applying the pocket function in WB Part design, an error message occurs "Failed to validate broken face".

Ideas for resolving this issue are mostly welcome.
BR

Lars
Attachments
PURIX A50 PipeSupportStructure ver01c.FCStd
(333.85 KiB) Downloaded 26 times
Best regards

Lars
Bance
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Re: WB Sheet metal - perforation and unfolding

Post by Bance »

Sketch symbol is far too complicated, rather make two sketches and use feature patterns.

I have deleted some of the geometry and used carbon-copy to make two simplified sketches. Note that when constraining tangentially, only select end points and the tangent constraint. For further reference see Sketcher_reference.
PURIX.png
PURIX.png (26.33 KiB) Viewed 614 times
Attachments
PURIX A50 PipeSupportStructure ver01cBance.FCStd
(477.71 KiB) Downloaded 24 times
drmacro
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Re: WB Sheet metal - perforation and unfolding

Post by drmacro »

Lars wrote: Sun Jul 05, 2020 4:10 pm changing the bending radius resolved the error when unfolding. Thank you for your support with this issue.

Only the issue related to cut out of the symbols remains. Symbols are contained in a sketch which is fully contained/defined. When applying the pocket function in WB Part design, an error message occurs "Failed to validate broken face".

Ideas for resolving this issue are mostly welcome.
BR

Lars
To directly answer: this error usually occurs when to vertices (line end points) are not coincident. Fully constrained does not imply this and if this condition exists, the shape is not closed. Thus the face that the shape defines is broken.

This is indeed the case with the curved shapes defined in the sketch named Symbol.

(I would also take @Bance advice and simplify these sketches.)

Sketch tips: favor geometrical constraints over dimensional. Always look for symmetry that will allow you to draw minimal sketches and take advantage of mirroring and transforms.
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."
Lars
Posts: 32
Joined: Sat May 05, 2018 10:39 am

Re: WB Sheet metal - perforation and unfolding

Post by Lars »

Thank you all for resolving these issues. Grateful for your support and assistance with FreeCad.

BR
Lars
Best regards

Lars
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