Unfold option Issue

[jaisekjames]

See Issue

https://forum.freecadweb.org/viewtopic.php?f=22&t=25281&start=150#p279502
please change from
unfoldLength = ( bendR + kfactor * thk / 2.0 ) * bendA * math.pi / 180
to
unfoldLength = ( bendR + kfactor * thk / 2.0 ) * bendA * math.pi / 180.0
Add decimal place to 180.

[shaise]

Thanks! I will take a look

[shaise]

Hi,

The 180.0 is not the problem. The problem is difference between European and American standard of k_facror (one of them is 1/2 the other). I have reverted it to the European standard, which is compatible with Ulrich's original unfolder script. Now both unfolding from your system, and Ulrich's system match.

[jaisekjames]

Thank you

[f3nix]

Thanks! :)

I have tested the changes and here are my observations.

Cases 1 and 3 work as expected now. 👍
I have a question about case 2. Should it use the kfactor set in the kfactor parameter (property).

It seems it uses 0.65 in this instance.

up Face7 k-factor: 0.65

Cheers,
Mateusz

[shaise]

The k factor in the properties are total different system and works only on sheetmetal prefolded using the sheetmetal WB. If you make a sheetmetal model using another system, you can only unfold it using the unfold button. The unfold button uses its own K-factor, and its the same factor for all folds. The properties system can set a different k factor to each fold.

[f3nix]

Ok. Here is what I'm doing.

1. Create body and sketch.
2. Draw a rectangle (82mmx90mm).
3. Pad it (4mm).
4. Create a bend.
5. Change default properties:
   • length: 82mm
   • radius: 4mm
   • kfactor: 0,86
   • reliefd: 0mm
   • reliefw: 0mm
6. Select face and click "Flatten folded sheet metal object".

The unfolded length is 182,33mm (which is different than other two unfold cases).

Report view says:
up Face7 k-factor: 0.65

It does not use the 0,86 kfactor that I have set in the bend property.

Is it the intended behaviour (workflow) or am I doing something wrong?

Here is the example file: L-bracket-final.zip

OS: Debian GNU/Linux buster/sid
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.15703 (Git)
Build type: Debug
Branch: master
Hash: 80f82b59db1bae91115921d7da3190f855e1041f
Python version: 2.7.15+
Qt version: 5.11.3
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: Polish/Poland (pl_PL)

Cheers,
Mateusz

[shaise]

Sorry if I wasn't clear,

The unfold button disregards ALL fold properties, and works with its own k-factor system.
The only way to use the k-factor in the the properties, is to set the unfold to true in the properties as well. This means, and I know its tedious, that if you want to unfold the entire object using the k-factor in the properties, you need to go fold by fold and set the unfold property to true as well.

[f3nix]

Thanks for clarifying. I think this issue has been resolved.

Thank you again! :)

Cheers,
Mateusz

[ceremcem]

@shaise

The unfold button disregards ALL fold properties, and works with its own k-factor system.
The only way to use the k-factor in the the properties, is to set the unfold to true in the properties as well. This means, and I know its tedious, that if you want to unfold the entire object using the k-factor in the properties, you need to go fold by fold and set the unfold property to true as well.

Wow! I was about to open an issue about "k-factor is not regarded while unfolding" and I just saw this explanation. What is the use case of this behavior? Why isn't the k-factor from the bend properties simply used while unfolding?

[ceremcem]

@jaisekjames I now think the issue is solved.

[luzpaz]

@shaise can this ticket be resolved?

[shaise]

yes, I think it can be closed