[PDN] Problem with additive pipe and multiple sections

[tom]

Hi,

I'm trying to create a part using the additive pipe tool in PDN. I want to loft the sketches001 to 004 along the selected path as shown in the picture.

pdnSweepTest1.png (261.8 KiB) Viewed 1514 times

All works fine, if I select only Sketch001 and Sketch002 and sweep along Edge1 of Sketch:

pdnSweepTest2.png (179.71 KiB) Viewed 1514 times

But as soon I add more sketches and lines for the path the result becomes unpredictable:

pdnSweepTest3.png (188.04 KiB) Viewed 1514 times

pdnSweepTest4.png (203.52 KiB) Viewed 1514 times

I know that it is important to have the normals of the sketches pointing in the same direction along the sweep path. I tried my best to achieve that, but obviously I did something wrong. It was very hard to see, where the normals of the datum planes point to. So, I had to map a sketch first on a particular datum plane. If the sketch pointed to the wrong direction, then I set the map reverse flag of that sketch in order to fix the normal.

Is there a recommended way of aligning sketches to get predictable results in the PDN additive pipe tool?

Further, during my tests I observed the transform mode is incompletely restored when editing an addictive pipe, if the transform mode is set to Multisession. In that case the list box containing the sections is missing in the GUI. Can somebody confirm that?

Attached is also the FC file I used in the tests. Note, that it simplified. The final part will not have any symmetry. So I can't just design one half and then the fuse it with its mirror.

Thank you for your help.

Regards,
Thomas

OS: Mac OS X
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.12964 (Git)
Build type: Release
Branch: (HEAD detached at 6a15a2f)
Hash: 6a15a2f31e84c014cdbc5dbf365ac58a6777963c
Python version: 2.7.14
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.1.0
Locale: German/Germany (de_DE)

[chrisb]

I will have a look at your file.
You should not zip the FreeCAD file (why that is explained in the forum guidelines). The zipped file saves 4K out of 75, that's not worth the hassle with the unzipping.

[chrisb]

The model you uploaded seems to be in a fancy state.
- If recompute the whole model some lines are added.
- If I delete the Sweep in order to rebuild it, I cannot see a single sketch. The same if I edit them. Is this the same at your's if you take the uploaded file?

OS: Mac OS X
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.17.12999 (Git)
Build type: Release
Branch: (HEAD detached at c8af1d1)
Hash: c8af1d16afee607f3125268c6f830ac7b815c33e
Python version: 2.7.14
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.1.0
Locale: German/Germany (de_DE)

[tom]

Hi chrisb,

I know that zipping the FC file does not help to shrink the file, but it helped me to upload the file at all. If I do not zip the file, then I can't select the .FCStd file in the File section dialogue. Also dragging the file into the forum message box (as suggested in the forum) did not help. However, I retried it again when writing this post and this time I was able to drag and drop even the .FCStd file. I have no idea, why it works now. Believe me, I really tried it several times before. BTW. adding the .FCStd file using the file selection dialogue still does not work. I'm on OS X 10.11.6 using Safari if that does matter...

Regarding the content of the document, I could reopen my file without any problem. But then I deleted the part-o-magic add-on and I was also in trouble opening the file. I will recreate the file without having part-o-magic installed. It will take some time...

[chrisb]

If I do not zip the file, then I can't select the .FCStd file in the File section dialogue.

I remember the post but didn't remember it was you. As you have seen I use MacOS too, but with Firefox and I never had any problems. Until recently I used El Capitan (I think that's 10.11) and now 10.13.2. I am sure you can teach Safari to accept arbitrary file types. If you don't succeed, please mention it on upload, because the additional effort for the helpers is not welcome at all - albeit only some clicks and inputs.

[tom]

Ok, here is a new FC document showing the problem - this time without having part-o-magic installed.

[NormandC]

Hi tom,

Your topic subject is misleading: it explicitly mentions the additive loft tool, but you are actually working with the additive sweep.

While the topic subject is misleading, it is actually right : IMO it is the proper tool to build this shape.

The distance between the profiles is too short to get a proper result with a sweep. And both ends are straight, easily made with a loft; the only curved part is the centre.

All that you need is to add a 5th section sketch on the YZ_Plane, and to work in separate steps instead of trying to get the shape in one go.

See my file attached.

FC017_Loft_instead_of_Sweep_01.png (46.25 KiB) Viewed 1465 times

BTW: perspective view is a nice mode for visuals, but a poor one for actual modelling, especially when editing sketches.

[tom]

Hi NormandC,

thank you for your effort and sorry for the confusion in the subject. I have corrected the subject in my previous posts now.

Unfortunately the problem is a bit more complicated. As I mentioned in my first post there is no symmetry in the real part. The attached model was only a very simplified version of a next step in my real model. So, the 5th section would be a bit harder to define. I have attached the model I'm working on:

kammaufsatz.png (495.51 KiB) Viewed 1452 times

https://drive.google.com/file/d/1VKkQxx ... sp=sharing
Note that the model was created with installed part-o-magic. As we already found out (see my previous posts) part-o-magic breaks the compatibility with FreeCAD installations not having part-o-magic installed although I did not (intentionally) use any feature of part-o-magic. But that is another topic, which I want to discuss in another thread. So, before you open the model, please install part-o-magic first. Otherwise you cannot change the visibility of any item. Don't forget to uninstall part-o-magic afterwards, if you do not need it any longer.

The next design goal im my project is to make the fins at the outer border thinner than at their root. I planned to used the subtractive pipe to form the gaps between the fins. In my test I used the additive pipe instead just to check, if my idea will work. Then I encountered the problem with the sweep and I thought that it may be of general interest, because IMHO a tool, which does not produce predictable results, is a useless tool. Of course before pointing to a supposed bug in the software I wanted to ensure that I used the tool in the proper way.

So in summary there are three issues to address next:

• Find a work-around for my real model (kammaufsatz4). Any idea of the community is welcome.
• Verify that the additional/subtractive pipe tool works in the intended way. Perhaps a developer should look at this.
• Check, why part-o-magic breaks the file compatibility. I will discuss this in anther thread.

Regards,
Thomas

[NormandC]

That is a nice looking model.

OK, I'll download your model and try to look at it.

One thing I didn't mention before, is that while testing the Additive sweep, before deciding on the use of loft, I thought I discerned an issue with profiles seemingly "flipping" when using sweep thus creating self-intersects. But I didn't analyze this much.