[BUG] TechDraw: Oblique sections do not run correctly

[Batucada]

I can only confirm the original bug.
The generated edges in an oblique section are not correct, but the generated hatch is.

Today's example would have been just a test to finish the project. Actually, I could have left it alone, because I had already included the 12 x 12 folding instructions in the drawing. And thus the section would have been an overdetermination. Somehow I was warned not to omit the section. In other drawings with oblique sections I wanted to determine the angle of edges in this way, but I can probably throw that out the window now. Because in these drawings it is not enough to conjure up the corresponding value in the drawing using TechDraw_LinkDimension. Because here I had relied on FreeCAD's ability to derive the corresponding angles from the model. So what else can I do but revise all these drawings and determine the angles by hand. It's a pity, really, because I could have finished much earlier, because a week ago I had already finished FreeCAD and it was precisely because of these angles that I reworked the FreeCAD objects once again in order to be able to offer them to TechDraw in a bite-sized form. I could have saved myself the work.

[domad]

Greetings to the Community!
In confirming the bug, I am attaching a workaround ...

[Batucada]

Greetings to the Community!
In confirming the bug, I am attaching a workaround ...

This is currently my solution

tan(alpha) = a/b

where a = 12 mm and b is the respective value taken from the drawing. This is not in accordance with the standard, but it is sufficiently accurate. And costs me a smile in the end. Nevertheless, I will take a look at your proposed solution. Thank you very much for the presentation.

Bildschirmfoto 2022-09-27 um 19.29.33.png (48.38 KiB) Viewed 433 times

and in addition th whole drawing

TD_AP10_RWDK_Deckseite.pdf

(229.94 KiB) Downloaded 18 times

[Batucada]

@domad
Hi there,

your solution, this is what I would have done on a Kuhlmann machine in the past. Here in TechDraw you have to set a lot of "cosmetic" points, points that I have also become friends with because they are helpful. So I know it's a painstaking job to set the points, a bit tricky but it can be done. It's also quite an effort just to confirm a measurement of how deep the fold should be routed. As I said, with this drawing it wasn't that important, there are a couple of other drawings where a corresponding angle needs to be specified to the tool default. The dimensions are all in FreeCAD in some form or can be developed from it. For this one angle, you don't need a whole section that goes across an entire object, it's enough if the section is indicated at the corresponding edge, it just has to be perpendicular to the edge, that's all.

[wandererfan]

Direction and SectionNormal are pointing in different directions. The cut is made according to SectionNormal and the projection is made according to Direction.

[Batucada]

Direction and SectionNormal are pointing in different directions. The cut is made according to SectionNormal and the projection is made according to Direction.

Why is this so complicated? If a certain cutting direction is set in SectionNormal, then the projection should be done as expected. The angle set in the example is clear, the direction of view of the arrows on the section line is also clear, the position of the section line is also clear! And now another setting is needed? As a user who has learned technical drawing at some point, you feel caught off guard at this point when a remote (not to say mysterious) setting produces an unwanted projection.

If the conditions mentioned above (angle, cutting position, viewing direction) are fulfilled, the user should not have to worry about further adjustments.