[SOLVED] Length Dimensions on Complex Oblique Edges

[maxrlx]

Dear Developers And Contributors,

Thank you for an excellent and useful software.

Dear All,

Could you please advise regarding the placement of "Length Dimensions" on complex oblique part views in TechDraw, in order to obtain the correct dimension as corresponding to the 3D model.

Freecad Info:

Code: Select all

OS: Ubuntu 22.10
Word size of FreeCAD: 64-bit
Version: 0.20.2.29603 (Git) AppImage
Build type: Release
Branch: (HEAD detached at 0.20.2)
Hash: 930dd9a76203a3260b1e6256c70c1c3cad8c5cb8
Python 3.10.8, Qt 5.15.4, Coin 4.0.0, Vtk 9.1.0, OCC 7.6.3
Locale: English/United States (en_US)

Context:
Attempted to place dimensions on oblique edges which are immediately followed by chamfers, but the "Length Dimension" is attached at an incorrect angle and returns an incorrect dimension.
Searched the forum and found a somewhat related topic but not exactly the same in viewtopic.php?t=69607 , but it did not help.
Incorrect dimensions, alignment and projections circled in red in attached images, and Freecad file attached with all attempted workarounds as separate pages.

ffp1_default_dimensioning.png (71.16 KiB) Viewed 973 times

Workaround Attempt 1:
Selected the incorrect dimensions and double clicked them and changed the dimension line and extension angles in the "Override angles" option to correctly match the part edge. That resolved the alignment issue, however the dimension remained unchanged and still incorrect.

ffp1_attempt_1.png (75.98 KiB) Viewed 973 times

Workaround Attempt 2:
Used "Cosmetic Parallel Lines" and "Cosmetic Intersection Vertexes" to extend part edge lines as to intersect each other and allow the "Length Dimension" to properly align itself and return the correct dimension. This worked, and provided the correct dimension alignment and value, however it is time consuming if there are many parts involved such as in a fabrication, and also there are many additional lines in the drawing creating visual clutter, and potentially not up to drawing standards.

ffp1_attempt_2.png (77.69 KiB) Viewed 973 times

Workaround Attempt 3:
Rotated the "Primary Direction (Front View)" of the "Projection Group" in the data tab "Rotation" option as to align the largest oblique edge to make the part horizontal. This worked quickly and efficiently, providing correct dimension alignment and value. However the rest of the secondary projection views are not updated to match the rotation of the primary view. I noticed that in the "Projection Group" dialog there are options to rotate the views at 90 degrees clockwise and anticlockwise, and when placed rotated from this dialog, all projections are correctly rotated, however the angles are locked at 90 degrees with no option to manually adjust.

ffp1_attempt_3.png (57.54 KiB) Viewed 973 times

Question:
Could you please advise if there is any alternative way not considered here to obtain the correct "Length Dimension" alignment on complex oblique geometry, or alternatively please advise if possible to implement custom angle of rotation in "Projection Group" dialog, as to rotate the primary projection to desired angle, and have it reflected on the secondary projections.

Regards and Thank you All in advance.

[chrisb]

Hi and welcome to the forum!

As a workaround you can place the object correctly before adding it to the page:

- add a sketch with the same orientation as Sketch
- turn it by the inverse angle you want to turn the TechDraw view (here 50° + 180°)
- turn the option to restore the view off in the sketch
- edit it - do nothing - close it
- add the view

[wandererfan]

Attempted to place dimensions on oblique edges which are immediately followed by chamfers, but the "Length Dimension" is attached at an incorrect angle and returns an incorrect dimension.

The minimum distance between Vertex0 and Edge3 is 100.12. To get a perpendicular distance, Edge3 must be extended.

OverrideAngles is normally used in isometric views to align the dimension and extension lines. It is not intended to change the dimension measurement.

I used TechDraw_ExtensionLineParallel to extend the edge between the 2 chamfers at both ends and then used point to edge dimensions to make this:

oblique_length_dims_v020.png (42.81 KiB) Viewed 837 times

[RalfG]

I prefer to work with "Cosmetic Intersection Vertex(es)" in these cases.

1.jpg (139.79 KiB) Viewed 805 times

the advantage from my point of view is that the points are not visible when the frame is switched (Turn View frames on/off).

2.jpg (123.44 KiB) Viewed 805 times

greetings

Ralf

[maxrlx]

Thank you all for the prompt reply and solutions.

The solution in post 2 by chrisb is what I was attempting to achieve, tried it and it works.

Regards and thanks.

[chrisb]

The solution in post 2 by chrisb is what I was attempting to achieve, tried it and it works.

Regards and thanks.

You're welcome. I am more pleased by the other solutions . I'm still learning FreeCAD.

[maxrlx]

I think learning FreeCAD is a lifelong journey.