How to remove a part of object

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grzesiug
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Joined: Wed Jun 19, 2019 8:22 am

How to remove a part of object

Post by grzesiug »

Hi
i have drawn almost whole model from attached scetch, but i don't know how to corect remove a part of pipe between two walls.
Pleas give me some advise.
Attachments
model6.FCStd
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model6.jpg
model6.jpg (886.67 KiB) Viewed 6185 times
Inkedmodel6.1_LI.jpg
Inkedmodel6.1_LI.jpg (45.4 KiB) Viewed 6185 times
chrisb
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Re: How to remove a part of object

Post by chrisb »

You can add the cylinder in two pieces from the outside, each of them going to first face.
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Olav
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Re: How to remove a part of object

Post by Olav »

This thread encouraged me to try for myself.

chrisb wrote: Sun Oct 04, 2020 2:33 pm You can add the cylinder in two pieces from the outside, each of them going to first face.
Not with a fillet in place, because then it goes from this:

Schermafdruk_2020-10-04_17-54-48.png
Schermafdruk_2020-10-04_17-54-48.png (268.3 KiB) Viewed 6136 times

To this:

Schermafdruk_2020-10-04_17-55-44.png
Schermafdruk_2020-10-04_17-55-44.png (290.33 KiB) Viewed 6136 times

(Resulting cylinder goes on for more than 9 metres in the Y-direction!)

You can't do the fillet after adding the cylinder either, because FreeCAD refuses to do it.

My provisional solution is to pad the cylinder to a fixed dimension (in this case 40mm conform the drawing). And then hollow the body out by making a boolean cut with a different (smaller) body I made for the purpose.

Menu_021.png
Menu_021.png (83.12 KiB) Viewed 6136 times

Still can't make all the necessary fillets though. I understand that people are working on the fillet problem in FreeCAD, I fervently hope they will succeed in fixing it.
Attachments
modelmania_2011_phase1.FCStd
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grzesiug
Posts: 11
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Re: How to remove a part of object

Post by grzesiug »

Thanks Olav, You are right.
I was thinking about boolean operation but I was hope that there is easier way.
Boolean cut solves problem.
Olav
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Re: How to remove a part of object

Post by Olav »

grzesiug wrote: Sun Oct 04, 2020 6:45 pm Thanks Olav, You are right.
I was thinking about boolean operation but I was hope that there is easier way.
Boolean cut solves problem.
You're welcome. Let me know If you succeed in making the fillets!
drmacro
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Re: How to remove a part of object

Post by drmacro »

The trick is to keep you fillets from impinging on other edges or creating coplaner issues.
modelmania.png
modelmania.png (172.11 KiB) Viewed 6057 times
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modelmania_2011_phase1-1.FCStd
(394.5 KiB) Downloaded 66 times
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Olav
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Re: How to remove a part of object

Post by Olav »

drmacro wrote: Sun Oct 04, 2020 7:46 pm The trick is to keep you fillets from impinging on other edges or creating coplaner issues.
Yes, and that's of course a good solution/workaround if you have complete freedom to decide on your model. But if you need to conform to given dimensions and specifications it may not always be an acceptable option.

Even worse is the fact that it can be quite unpredictable. Sometimes compound/complex fillets will work just fine, then you change an unrelated thing in your design and FreeCAD will suddenly refuse making the fillets that previously were no problem for it at all. Or even crash.

Again, I'm aware that the developers are aware of this. So I'm not complaining and I'm waiting patiently but with great anticipation for it to be resolved.
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Vincent B
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Re: How to remove a part of object

Post by Vincent B »

Freecad doesn't like this tricky fillet, but with some approximation... ;)
link to download: https://mon-partage.fr/f/vmusgfLD/
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freedman
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Re: How to remove a part of object

Post by freedman »

I moved the outer radius sketch (of the pipe) down a ways and created the fillet, then moved the sketch slowly back up and got within a micron of having the two top edges aligned. Not bad.
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meeting1.JPG
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mrdic
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Re: How to remove a part of object

Post by mrdic »

Years ago, ACIS used to have the same shortcoming, but a minutely small sphere centred at the degenerative convergence point subtracted from the part would permit the filleting and could be ignored in production. I remember doing this exercise, from the annual SolidWorks University that Dassault Systemes used to convene in the US, with TurboCAD V10, using that technique.
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