How to remove a part of object

Post here for help on using FreeCAD's graphical user interface (GUI).
Forum rules
and Helpful information
IMPORTANT: Please click here and read this first, before asking for help

Also, be nice to others! Read the FreeCAD code of conduct!
grzesiug
Posts: 7
Joined: Wed Jun 19, 2019 8:22 am

How to remove a part of object

Postby grzesiug » Sun Oct 04, 2020 2:14 pm

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
(248.85 KiB) Downloaded 12 times
model6.jpg
model6.jpg (886.67 KiB) Viewed 504 times
Inkedmodel6.1_LI.jpg
Inkedmodel6.1_LI.jpg (45.4 KiB) Viewed 504 times
chrisb
Posts: 30663
Joined: Tue Mar 17, 2015 9:14 am

Re: How to remove a part of object

Postby chrisb » 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.
You need at least FreeCAD 0.19.23300 to edit my current sketches.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
Olav
Posts: 96
Joined: Sun Nov 27, 2016 7:58 pm
Location: .nl

Re: How to remove a part of object

Postby Olav » Sun Oct 04, 2020 4:12 pm

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 455 times

To this:

Schermafdruk_2020-10-04_17-55-44.png
Schermafdruk_2020-10-04_17-55-44.png (290.33 KiB) Viewed 455 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 455 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
(216.78 KiB) Downloaded 20 times
grzesiug
Posts: 7
Joined: Wed Jun 19, 2019 8:22 am

Re: How to remove a part of object

Postby grzesiug » 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.
Olav
Posts: 96
Joined: Sun Nov 27, 2016 7:58 pm
Location: .nl

Re: How to remove a part of object

Postby Olav » Sun Oct 04, 2020 7:13 pm

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
Posts: 2331
Joined: Sun Mar 02, 2014 4:35 pm

Re: How to remove a part of object

Postby drmacro » Sun Oct 04, 2020 7:46 pm

The trick is to keep you fillets from impinging on other edges or creating coplaner issues.
modelmania.png
modelmania.png (172.11 KiB) Viewed 376 times
Attachments
modelmania_2011_phase1-1.FCStd
(394.5 KiB) Downloaded 7 times
Star Trek II: The Wrath of Khan: Spock: "...His pattern indicates two-dimensional thinking."

My beginners, written treatise: Learning FreeCAD
Olav
Posts: 96
Joined: Sun Nov 27, 2016 7:58 pm
Location: .nl

Re: How to remove a part of object

Postby Olav » Sun Oct 04, 2020 9:09 pm

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.
User avatar
GlouGlou
Posts: 2749
Joined: Sun Apr 05, 2015 9:02 am
Location: La Rochelle, France

Re: How to remove a part of object

Postby GlouGlou » Sat Oct 10, 2020 5:35 pm

Freecad doesn't like this tricky fillet, but with some approximation... ;)
link to download: https://mon-partage.fr/f/vmusgfLD/
Attachments
Capture.JPG
Capture.JPG (51.71 KiB) Viewed 241 times
freedman
Posts: 1731
Joined: Thu Mar 22, 2018 3:02 am
Location: Washington State, USA

Re: How to remove a part of object

Postby freedman » Sat Oct 10, 2020 8:17 pm

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.
Attachments
meeting1.JPG
meeting1.JPG (42.53 KiB) Viewed 217 times
mrdic
Posts: 86
Joined: Wed May 10, 2017 4:25 am

Re: How to remove a part of object

Postby mrdic » Sun Oct 11, 2020 1:02 am

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.