Sheet Metal Workbench

[papyblaise]

You must do the extension before the second bend , and you must do a add bool the U+exten and do "refine = true
I kno isn't easy to understand

[shaise]

you must do a add bool the U+exten and do "refine = true

Where do I set it?

[gordo89]

I used the following in the end.

part workbench --> join walled object --> connect objects.

below is the outcome which looks correct so far.

[papyblaise]

yes it's correct

[thebighaggis]

Hi All

I'm having trouble here... I had a dxf file I wanted to fold up into a channel and it only folded one side and failed when I tried to do the other side..
so I tried from scratch using Part Design WB with a basic rectangle 200x100x2mm adding fold wall sketches 20mm in from the sides... I've also tried this on FC 0.18 ver and same result..using 0.19 now for most things... see below screenshot and error message plus file uploaded... and version info..

Error:
Traceback (most recent call last):
File "C:\Users\TheBigHaggis\AppData\Roaming\FreeCAD\Mod\sheetmetal\SheetMetalFoldCmd.py", line 203, in execute
invertbend = fp.invertbend, selFaceNames = fp.baseObject[1], MainObject = fp.baseObject[0])
File "C:\Users\TheBigHaggis\AppData\Roaming\FreeCAD\Mod\sheetmetal\SheetMetalFoldCmd.py", line 174, in smFold
resultsolid = BOPTools.JoinAPI.connect(solidlist)
File "C:\Program Files\FreeCAD 0.19\Mod\Part\BOPTools\JoinAPI.py", line 67, in connect
new_list_of_shapes.extend( compoundLeaves(sh) )
File "C:\Program Files\FreeCAD 0.19\Mod\Part\BOPTools\Utils.py", line 73, in compoundLeaves
if shape_or_compound.ShapeType == "Compound":
<class 'AttributeError'>: 'NoneType' object has no attribute 'ShapeType'
972.546 <App> Document.cpp(3715): Failed to recompute Unnamed1#Fold001: 'NoneType' object has no attribute 'ShapeType'
Recompute failed! Please check report view.

Version Info:
OS: Windows 10 (10.0)Version Info:
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.20477 (Git)
Build type: Release
Branch: master
Hash: 7d8ab175a68e476427e6e337fe3099b52da49dc8
Python version: 3.6.8
Qt version: 5.12.1
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/Australia (en_AU)

[jaisejames]

First delete all fold[ignore error on sketch not on face]. Please do first second sketch as first fold. then first as second fold.

sheet metal bend.png (20.83 KiB) Viewed 1264 times

[thebighaggis]

Hi jaisejames
Thanks, and I did try that and it worked but it seems very unstable, I need the inside folds
to be 2mm Radius [ typical inside bend radius = material thickness ] I had to do this as I created
the part the way you showed me 1 fold at a time or I just get errors going back to change the radius
afterwards..
It's also interesting that the blank when flattened back out again it is not correct, original blank size
is 76mm when flattened out with 2mm radii it is not the same..however I have a work around , it was to
edit the kfactor in the bend properties to 0.17 and use ansi Kfactor 0.5 when using the flatten tool..
I think the calculations used to fold up sheet metal is not correct... hence the fudging of the Kfactor
I'm attaching finished part and drawing for your reference.. I double checked that my refold method
was accurate , I use Autodesk Inventor and it was very close,,,, well close enough for sheet metal
Thank you for posting back the answer...much appreciated, I hope some people also get some use out
of my solution to make the part stretch the material correctly when using the fold wall & flatten tool ...
BTW I had to cheat and make the bend radius 1.99mm because of a cutout close to the bend
Just Redid the Part & the 2mm Radius worked, the one where the cutouts are, I wonder why it didn't
work the 1st time??

Best Regards
Haggis [ John Hyslop ]

[thebighaggis]

Hello again..

Could I make a suggestion to have a prompt after the fold wall icon is selected
to offer input as:-
1: Material Thickness
2: Inside Bend Radii
3: Kfactor

All the commercial software I've used have these parameters preset
and when it is flattened it retains it's correct blank size ( the original size )
and when folded up stretches the material according to these settings..

Just a thought.. otherwise.. it's a great add on for the sheet metal WB

I have manually edited SheetMetalFoldCmd.py Line 194
Set kfactor = (0.16,0.0,1.0,0.01) "just so I don't need to change all the time"
as long as you change the radius to suit the material thickness on the bend this setting is very close,
the folds stretch correctly and when you use the flatten tool your blank is very close to what you started
with rather than being smaller...so it's basically simulating what would happen to your blank in real life.

Is there a way to get the radius value in the script from the Pad thickness?

Thanks again for your help..

Cheers
Haggis

[chrisb]

All the commercial software I've used have these parameters preset
and when it is flattened it retains it's correct blank size ( the original size )
and when folded up stretches the material according to these settings..

I think thats the wrong process. It resembles a process of "Hey, I have this piece of metal, lets see what I can make of it". While SheetMetal works the other way round: "Hey, I have this model, how do I have to cut the sheet metal to get exactly this after bending".

[easyw-fc]

Could I make a suggestion to have a prompt after the fold wall icon is selected
to offer input as:-
1: Material Thickness
2: Inside Bend Radii
3: Kfactor

Is the method in the README.MD the one you need?

Material Definition Sheet
You can use a Spreadsheet object to declare K-factor values inside the project file permanently. This will allow:
Different K-factor values to be used for each bend in your model
Sharing the same material definition for multiple objects

FreeCAD_SheetMetal/README.md