'Cut' fatal error

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chrisjc31415
Posts: 8
Joined: Sat Apr 16, 2011 8:15 am

'Cut' fatal error

Post by chrisjc31415 »

Hi All,
I'm using FreeCAD to design an LED torch. I'm using the latest 0.12 unstable version on Windows, but I had the same problem with 0.10 on Windows.
The problem occurs when I try to 'Make a cut of two shapes'. I have the torch body, and a 'lense cover'. When I attempt to 'cut' the lense cover from the body, I get 'A fatal error occured when running a boolean operation'.

I have attached the offending design file. To create the problem, select object 'Cut' and 'LenseCover001' and click 'Make a cut of two shapes'.

Is it a bug?, or am I doing something wrong?

Many thanks,

Chris.
Attachments
Cut-problem.zip
(207.28 KiB) Downloaded 53 times
wmayer
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Re: 'Cut' fatal error

Post by wmayer »

This is a problem of the cad kernel OpenCascade we're using. From this library it is known that boolean operations usually are very slow and often fail with complexer objects.
wmayer
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Re: 'Cut' fatal error

Post by wmayer »

Not sure which objects you want to cut but according to your description you want to cut "LenseCover001" from "Cut". If I select first "Cut" then "LenseCover001" and press the boolean cut button it returns a valid shape back.

See attach project file.
Attachments
Cut-problem.FCStd.zip
(273.61 KiB) Downloaded 55 times
chrisjc31415
Posts: 8
Joined: Sat Apr 16, 2011 8:15 am

Re: 'Cut' fatal error

Post by chrisjc31415 »

Thanks for the quick reply!

Apologies for being dull, but I can't find a way to import your attachment into FreeCAD ? (I can load the individual .brp files, but not the whole project...)

With regard to your comments about OpenCascade, this design is a long way from finished. Are you saying that OpenCascade is not up to the job?, or is there a better approach to constructing complex 3D objects?

Thanks,

Chris.
wmayer
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Re: 'Cut' fatal error

Post by wmayer »

Apologies for being dull, but I can't find a way to import your attachment into FreeCAD ? (I can load the individual .brp files, but not the whole project...)
Just remove the .zip extension from the file. But just in case it's damaged here is the zipped brep file.
With regard to your comments about OpenCascade, this design is a long way from finished. Are you saying that OpenCascade is not up to the job?, or is there a better approach to constructing complex 3D objects?
No, I would not say that OpenCascade is not able to manage bigger projects but from time to time you'll possibly run into some problems like boolean operations or so. But it's not said that commercial cad kernels do a better job. And in this case I think the boolean operation was OK (if I took the right shapes).
Attachments
shape.zip
(38.97 KiB) Downloaded 41 times
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NormandC
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Re: 'Cut' fatal error

Post by NormandC »

Hi,

Hope you won't mind me butting in :)
wmayer wrote:If I select first "Cut" then "LenseCover001" and press the boolean cut button it returns a valid shape back.
Yes, the selection order is important. The first selection should be the body which is cut, and the second the cutting object.

Out of curiosity, I checked your file. Is there a design reason/intent why your lenscover required so many operations to make? Because it could have been done in only two operations: one flattened box 90x90x1mm, with 4 rounded edges of 27.5mm radius. If you use the fillet command from the Part Design workbench (note: not the fillet tool from the complete workbench or the Part workbench), the fillets will be parametric. This way your model is more manageable, and I believe reducing the number of boolean operations make it less subject to build errors.

Hint: to use the Part Design's Fillet tool, first select on your shape the edges to apply the fillet to, then click on the fillet tool. 0,20mm fillets will be applied. Then go to the Data View to change the radius to the desired value.
Attachments
lenscover.FCStd.zip
remove the .zip extension to open in FreeCAD
(6.2 KiB) Downloaded 46 times
chrisjc31415
Posts: 8
Joined: Sat Apr 16, 2011 8:15 am

Re: 'Cut' fatal error

Post by chrisjc31415 »

wmayer wrote: Just remove the .zip extension from the file. But just in case it's damaged here is the zipped brep file.
Thanks. I wouldn't have realised it was that simple.
wmayer wrote:... And in this case I think the boolean operation was OK (if I took the right shapes).
Definitely didn't work for me, :( But I can use your file.
normandc wrote:Is there a design reason/intent why your lenscover required so many operations to make?
Yes, the reason is that I am a total noob! :oops: I haven't experimented with fillets yet.
However, I am grateful for your suggestions, and in fact I can use the filleted box to construct the main body of the part as well.
I think I will start again using filleted boxes as it will take far fewer components.

Thanks all for helpful comments!

Chris.
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NormandC
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Re: 'Cut' fatal error

Post by NormandC »

Hi,
chrisjc31415 wrote:
wmayer wrote: Just remove the .zip extension from the file. But just in case it's damaged here is the zipped brep file.
Thanks. I wouldn't have realised it was that simple.
It's actually a workaround for the fact that for attachments, the forum supports a very limited number of file extensions, .zip among them.
chrisjc31415 wrote:
normandc wrote:Is there a design reason/intent why your lenscover required so many operations to make?
Yes, the reason is that I am a total noob! :oops: I haven't experimented with fillets yet.
No problem, we all have to start at the beginning. :)
chrisjc31415 wrote:Thanks all for helpful comments!

Chris.
Glad I could help! Don't hesitate to hang around if you have other questions. :)

Norm
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