[Solved] Compound Boolean Cut Problem

[JeffM]

Hi,

I'm working on a complex semi-cylindrical case design, it's perforated with multiple cut-outs.

After much trawling and experimentation I've decided that probably the only way I can do what I want is with a compound boolean cut.

In the image below you can see the case in grey with the compound boolean cuts highlighted in green.



Individually all of the cuts work, but when I compound them some of them do, some don't.



If I look in the dependency graph I can see a link between 2 elements highlighted in red, but having looked at the components I can't see what's wrong. In any event, if I remove them from the compound it makes no difference, some of the cuts still don't work.

File is here:

https://www.dropbox.com/preview/Case%20 ... e=personal

It's driving me crazy, I'd really appreciate some help.

Thanks,

Jeff

OS: Windows 10
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.4 (GitTag)
Build type: Release
Branch: releases/FreeCAD-0-18
Hash: 980bf9060e28555fecd9e3462f68ca74007b70f8
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedKingdom (en_GB)

[chrisb]

I cannot currently reach dropbox, so I cannot test. But it looks as if some of the objects in the compound overlap. In that case you should use a Union instead, otherwise more than one objects tries to cut the same thing and that probably leads to the issues you see.

[JeffM]

Aha, OK, that makes sense, it is only the overlapping cuts that are affected, I'll give it a try.

Thanks Chrisb

[kisolre]

You tried to share a link to the file opened in your dropbox instance opened in a browser. To share the file you should select the file, click the "Share" field after the file name, Share with dropbox, create a link.

[JeffM]

Sorry about the link, I don't really share files that often.

Anyway, problem solved after some deconstructing compounds, deleting parts the seemed to have replicated themselves, fusing and re-compounding here's the result....



Now I need to try to add a couple of small elements using the sheet metal tool, that may result in another cry for help.

Thanks for the support.

[JeffM]

Unsurprisingly, there is a continuation. I've discovered 2 more issues, one of them I've solved...ish.

In trying to add bends to the boolean cut casework using the sheet metal tool I was getting some strange behaviour, bends wrapping around on themselves, being kinked, not having the cut edge at 90 degrees to the sheet face. I fixed that by extending the face first (green line/blue arrows), by only 0.01mm, then I added a bend to that. It worked fine.



However, the other problem, that I can't seem to find a solution to, is that in trying to add fillets to the corners (red arrows) I get an 'Active Body' error, presumably because the cut casework is now sitting below a series of bends in the tree. I wondered whether I could migrate, or something like that to enable me to have an active body, but it wouldn't have it.



I have to say, it is quite challenging using Freecad for this type of casework, but I'm learning a lot from the exercise and am determined to persevere.

Any suggestions would be most welcome.

Thanks,

Jeff

[chrisb]

With using the Boolean Cut on the bodies (yes I hope you applied it to the bodies, and not to some feature inside) you have left the PartDesign level. So the bends are outside of PartDesign.
You can now continue to model in Part workbench, or you can create a new body with the Part object as BaseFeature, i.e. select the object and create a body. Then you are in the PartDesign world again.

If you decide to do so, you may consider to do this immediately after the boolean cut, or you may consider to use the PartDesign Boolean cut instead. SheetMetal is one of the workbenches which can be used inside and outside of PartDesign.

[JeffM]

Thanks Chrisb, I hadn't realised you could create a new body using the cut as a base feature, that's useful. However, one forward, one back....

Taking the new body and applying a fillet to the uppermost case corner (A) works, but trying to do the same thing at the outside edge of one of the cut-outs (B) fails, with a message about not being able to apply a fillet to multiple bodies. Don't understand that.



Also the strange bend behaviour persists, I think I will need to revert to adding a microscopic extension to the cut edge before applying a bend. It's probably associated with trying to apply a bend to a curved surface, the extension overcomes it. Here you can see a small gap between the surface of the material and the added bend (without applying an extension).



In plan you get a kinked bend development, with the added sheet material taking the form of a parallelogram, but probably at 90 to the casework, whereas the bend looks overbent.



Any thoughts as to why I might be able to fillet one corner but not another?

Thanks,

Jeff

[chrisb]

Any thoughts as to why I might be able to fillet one corner but not another?

Can you upload the model?

[JeffM]

Thanks Chrisb,

Bizarrely, having gone back to the original model and having created a new body from the base feature I can now add the fillet. I didn't do anything differently to last time. Strange.



The thing that's bothering me now is that I would like to get the base model back to it's original cut state before I added any bends. Unfortunately as the bends are external to cut001 if i delete the bends it deletes the underlying model. How can I fix that?

A bit of an aside but how do people ever run training courses on parametric modelling? I'm now a few months into Freecad and pretty much every day I come up against a new challenge. I really appreciate the support I get from the forum.

Hopefully the dropbox link will work this time, thanks kisolre

https://www.dropbox.com/s/epunzgbhcogsj ... FCStd?dl=0