Sweep a selected sketch along a path or to other profiles

[chrisb]

It does not fix your your model, but you should not use a feature from inside of a body in a Part boolean operation, take the body instead. Perhaps the problem comes from some coplanar issue with the tangents in the sweep's center.

I would go a different way anyway: Model it all in PartDesign and instead of an additive sweep use a subtractive and cut it directly from the body.

[chrisb]

You have to change the path so that you don't have any self intersections. Then it works.

[plgarcia]

Ok that is a constraint.
This intersection is required for me so I have to design the thing in a different way.

Why this constraint? Could not it be removed?

I removed the straight part of the profile. And then the cut works. But :
- the profile is reversed.
- mark to recompute and recompute does not change anything, as deleting the cut and recreate it does. It should be equivalent!

This is again something that should work and does not.

Regards
Pascal Garcia

[plgarcia]

New try,
I made the profile symetric so I do not have to bother about the orientation. The idea is be build another pipe and both pipe added could make make it.

But I understand I have also to cut the path in two.
For the first profile:
First part : the old path without the straight part. Fine seems to be OK.
Second part: with the straight part of the path only.
The preview while building quite good:

Capture610.JPG (102.2 KiB) Viewed 562 times

Then OK:

Capture611.JPG (84.74 KiB) Viewed 562 times

What!

Sorry could somebody agree this function is not stable enough and need some improvement!

I am using FreeCAD very basically, only for CAD, but with complex shapes I agree.
I found many cases where FreeCAD fails (on tangent faces, drags and drops not working, infinite loops, broken structures, and now the pipes, only for those I remind).
I encountered problems in most personal projects I have conducted. To be able to go further, I had to imagine a way not having FreeCAD failing (adding an epsilon here not to have coincident faces, adding and cutting parts instead of directly extruding them, … and sometime just giving up).

I know FreeCAD is also far more than basic CAD. But, as long as the basic stuff is not implemented, does not functioning perfectly in an efficient way, FreeCAD will not take the major place it has the opportunity to take as somehow unique in variety of functions for a CAD system in open world.
In the forum I have been answered quite often, it is not FreeCAD but OpenCascade failing.
The fact is that many cases are really FreeCAD stuff (drags and drop, the colors messed up, the current case), and for the others where OpenCascade fails FreeCAD should take that over, and manage not to have OpenCascade failing, and/or act with OpenCascade team to correct the problems.
A user who decides to use FreeCAD does not bother if OpenCascade has or not been integrated and that the problem comes from OpenCascade. His problem is that FreeCAD as a whole does not work.

I think you should really step back a little and think solving all these glitches, interface with OpenCacade. It does not mean stopping the development of all other functionalities, but put some effort in the core. I spent some hundreds of hours analyzing the code to try to solve the problem of mixing colors, and concluded that some software architecture restructuring is needed, and I have started doing that with some success. But I do not master and understand everything in FreeCAD, I do not have the time for that and there is not much documentation available for that. I missed a committee you should create if not exists, to decide what changes should be made in what order not to break FreeCAD. I request that many times in my post.

And if OpenCascade is really the source of many problems that cannot be worked around or corrected by OpenCascade team, the interface with OpenCascade should be concentrated in specific modules to, at some point, be able to replace it by something else.

It would be a pleasure to participate if you feel I can be of any help.

Here is the file

test.FCStd

(54.93 KiB) Downloaded 24 times

Regards
Pascal Garcia

[chrisb]

If you have followed the development of 0.18 you could have seen, that very much of the development is fixing and cleaning.

Did you try to model all in one body?

[plgarcia]

All sketches are in one body and the pipes also.
Is that what you mean?
Did you see the last example I gave you?

To summarize I have not been able to make the model I wanted with FreeCAD.

This step copying does not show up. But nevertheless should not induce errors.

For cleaning you have an example with at least three problems to solve:
- damaging the internal structure when renaming a Sketch used in a pipe
- this last problem building a pipe that ends with a face!
- the recalculate not functioning for a pipe.
- it is not possible to delete a pipe when a second pipe is using the same sketch in the body,
- there is an infinite loop when changing the corners on a pipe probably auto-intersecting.
...

Some improvements suggested.:
- Managing the orientation of the sketch,
- Being able to choose the center of a sketch to extrude instead of taking the relative position.
- Managing auto intersection on a pipe.

But FreeCAD is more stable and data corruption do not occur as often as it used to.

But, unless it is a very recent change, a few days ago tangent faces were still not functioning. The drags and drops in the tree view are still not corrected and still corrupt the data structure with some moves, the correction I pushed for that was obviously not accepted, the colors are still calculated with two different means when the part is created and when the part is re-drawned what needs code restructuring and is complex I agree.

Sorry I know you are not responsible for all this, but today I feel it painful and I am quite upset. Apologize for that but sometime things are to be said!

Regards
Pascal Garcia

[chrisb]

I had missed the last model uploaded. I investigated it and it is again the tangency which produces the issue. In the attached file I have dislocated the arc by 1 micrometer and that works.

[plgarcia]

I do not understand.


At this level I would expect AdditivePipe to contain the 3 first segments and AdditivePipe001 to contain the last one.

But why when I display AdditivePipe001 the display shows the tube along the full path as it includes only edge4: the straight part of the path as shown in edit window.
AdditivePipe and AdditivePipe001 should behave somehow the same but with different part of the path.

Capture620.JPG (42.08 KiB) Viewed 524 times

Capture621.JPG (33.56 KiB) Viewed 524 times

Capture622.JPG (72.9 KiB) Viewed 524 times

Where am I wrong?

Or should both part defined in a different body?

If not a bug this makes no sense to me.

But anyway: This problem of tengent faces is a such huge source of problems! When will it be solved!

Regards
Pascal Garcia

[chrisb]

In Part Design you model features and not separate solids. And these features add or subtract material. The last feature represents the whole history and not only the material added or removed. So it is correct that AdditivePipe is part of the loop and AdditivePipe001 is that part plus the remaining part added by the feature.

[plgarcia]

Ok I understand.
Thanks for taking the time.

For the moment the body cannot be removed to the cut part that is the overall shape this pipe should be removed, it ends with an error, again a tangent face probably.
Still not to the end.

And I still have now to model the external part to be removed, you remember the profile was not originally symmetric.

That is the hart heavy that I have made this decision to have a look to another software as SolidCAD, Blender, Fusion360, Blender, and many others, as backup solution where FreeCAD falls into traps, as these tangent faces that are really a pain and that occur to often to be considered as a simple glitch.

I will continue to use FreeCAD for sure for simple things hoping someday it will be more "stable" and "reliable". The word are not the best chosen I agree, but I am pretty sure you understand what I mean. I have spent really to much time trying to find workarounds and my project of building a robotic hand has been delayed and is not finished, and my contributions on FreeCAD are not either significant enough to satisfy my ego and are not even considered by the community.

I hope anyway that this time is not completely lost, and you could ear what I am saying here and help you to take the best decisions to bring the project forward and make it reliable and stable to become a reference widely used by industry.

Regards
Pascal Garcia