Reshaping AdditivePipe

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SynchroM
Posts: 3
Joined: Wed Jan 19, 2022 4:51 pm

Reshaping AdditivePipe

Post by SynchroM »

My config:

macOS 10.16
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24366 (Git)
Build type: Release
Python version: 3.9.7
Qt version: 5.12.9
Coin version: 4.0.0
OCC version: 7.5.3
Locale: C/Default (C)

I'm new to FreeCAD, and finding it very hard going. I'm working in PartDesign, trying to make a replacement yoke for some headphones. I thought I had a grasp of how AdditivePipe worked: make two sketches for the profile and path, then sweep one over the other. That worked the first time I did it, but then I added some more pieces, printed a prototype, and realised I needed to reshape my path. When I edited the sketches on which the pipe is based, the pipe shape did not update. I found that the other pieces had apparently made some kind of uneditable copies of the pipe, and so the original pipe was not used – and after I deleted the pipe (not listed anywhere in the doc structure), it was still visible in some views. So I've backed out and I'm back to the two sketches. But the other parts of the model seem to be attached by some invisible means and when I try to sweep it again, I get an error saying "Failed to validate broken face", so I seem to be stuck.
Screenshot 2022-01-19 at 18.27.37.png
Screenshot 2022-01-19 at 18.27.37.png (69.63 KiB) Viewed 473 times
This is what it looks like:
Screenshot 2022-01-19 at 18.07.27.png
Screenshot 2022-01-19 at 18.07.27.png (36.56 KiB) Viewed 473 times
I added two primitive boxes that overlap, and applied a pocket to one of them. Even though these are entirely independent things within this body, there seems to be some invisible join between them and the sketches for the pipe. If I hide the boxes of the pocket, they reappear as soon as I try to make the pipe.

If I edit either sketch, the boxes also appear within the editor, obscuring part of the sketch, which makes them difficult to edit:
Screenshot 2022-01-19 at 18.22.26.png
Screenshot 2022-01-19 at 18.22.26.png (29.74 KiB) Viewed 473 times
Screenshot 2022-01-19 at 18.23.15.png
Screenshot 2022-01-19 at 18.23.15.png (32.07 KiB) Viewed 473 times
How can I separate these things so that I can recreate the swept shape? How can I have the swept shape update if I edit the sketches it's based on? Isn't that how it's meant to work?
TheMarkster
Veteran
Posts: 5505
Joined: Thu Apr 05, 2018 1:53 am

Re: Reshaping AdditivePipe

Post by TheMarkster »

I think you have the profile and the path sketches mixed up. It can't validate the path sketch because it's not closed. Try this: select the profile sketch in the tree view and the path to follow in the 3d view, then click the sweep toolbar icon.

The additive boxes are part of the Part Design solid feature chain and will be part of the pipe once you get it working. You can remove them by deleting them.

There is a tool in the sketcher to hide the parts of objects that are obscuring the sketch.
Snip macro screenshot-5426aa.png
Snip macro screenshot-5426aa.png (99.77 KiB) Viewed 466 times
A picture is worth a thousand words, and a file, a thousand pictures.
SynchroM
Posts: 3
Joined: Wed Jan 19, 2022 4:51 pm

Re: Reshaping AdditivePipe

Post by SynchroM »

I did think of that, and I was sure I'd tried it, but I tried it again and it worked! Thanks for the pointer.

I'm running into a follow-up problem. I want to re-use an existing sketch to create a new component that fits together with the other one. I have created a new body, copied the original sketch (and deselected all items linked to it when copying):
Screenshot 2022-01-20 at 17.50.56.png
Screenshot 2022-01-20 at 17.50.56.png (64.41 KiB) Viewed 409 times
and successfully pasted it into a new body:
Screenshot 2022-01-20 at 17.54.48.png
Screenshot 2022-01-20 at 17.54.48.png (32.13 KiB) Viewed 409 times
However, when I pad the sketch, parts from the other body reappear with it:
Screenshot 2022-01-20 at 17.55.01.png
Screenshot 2022-01-20 at 17.55.01.png (15.79 KiB) Viewed 409 times
These are not listed in the object hierarchy for this body, so I don't know why they are reappearing. How can I get an independent copy of a sketch with no ties to other objects?
SynchroM
Posts: 3
Joined: Wed Jan 19, 2022 4:51 pm

Re: Reshaping AdditivePipe

Post by SynchroM »

Never mind – I found that the right way to do it is to select the sketch and choose "Duplicate selected object" from the edit menu. This gives the same pop-up as the copy dialogue, but doesn't seem to bring any excess baggage in the copied object.
chrisb
Veteran
Posts: 53785
Joined: Tue Mar 17, 2015 9:14 am

Re: Reshaping AdditivePipe

Post by chrisb »

It seems to me that you haven't really understood what a PartDesign feature such as Pad or Pocket is. These are not standalone objects, they are cumulative and represent the result of adding and subtracting all previous features plus the one you are just looking at.
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