Is there a way to relocate a diameter’s dimension line to somewhere outside the circle that it measures?

[wisecad]

Dear FreeCAD team/community,

Happy father's day!

- Introduction (you can skip this detail and go directly to the problem section):
I am working on a model that has a series of diameters for which I want to provide dimensions as seen in the first uploaded image further down.

Problem: However, there will be other structures on top of the opening/hole shown in the image below, that will obstruct the dimension line from being seeing easily. Also, I am aware that a diameter’s dimension text can be relocated, but the line stays the inside the circle it measures.

QUESTION: Is there a way to relocate a diameter’s dimension line to somewhere outside the circle that it measures? That way, it would look more the way segment’s dimensions or point-to-point dimensions look, as seen on the image (orange-colored dimension lines/text) below.

Software-Freecad-Issues-10-RelocatingDiameterDimensionLines-01.jpg (77.46 KiB) Viewed 1076 times

Here is also an example of what I would like to do but done using another (its name shall not be uttered) application.

Software-Freecad-Issues-10-RelocatingDiameterDimensionLines-02-Skp.jpg (53.96 KiB) Viewed 1076 times

Thanks in advance for your time and for your answers.

Cheers

Raoul

[heda]

seems like you are doing it in draft, and yes, if you do it as linear and fiddle around with prefix and positions it is possible to do it in draft
(the properties are in the view tab)

Snip macro screenshot-529f6d.png (38.43 KiB) Viewed 1053 times

or do it in techdraw, which I guess is what most people would recommend to do it in.

[wisecad]

seems like you are doing it in draft, and yes, if you do it as linear and fiddle around with prefix and positions it is possible to do it in draft
(the properties are in the view tab)

or do it in techdraw, which I guess is what most people would recommend to do it in.

Hello Heda! Thank you for your post.

You are correct. I am trying to do it using the draft workbench. I have been trying to add a linear dimension, but I ran into an obstacle. The outer circle in the tubular structure contains an odd number of segments (29 to be exact), which makes it impossible to find a good reference point to create a linear dimension that truly reflects the dimeter of the circle. Tried to find a way to control how many segments are added to a polygon used to represent a circle but failed. See the image below.

Software-Freecad-Issues-10-RelocatingDiameterDimensionLines-03-OddSegmentNumberPolygon.jpg (112.19 KiB) Viewed 1028 times

Curiously, the inner circle in that same structure has an even number of segments. Is there a way to control how many segments are used in a polygon used to represent a circle?
In addition, I could not find a property in the view tab called “prefix” for linear dimensions. I wasn’t able to find a “position” property in the view tab either. In the data tab I have the “Dimline”, “End” and “Start” properties, which I can use to help me fine-tune the positioning of linear dimension lines. Are these properties in the data tab what you meant?

With regards to using the Techdraw workbench, I am still very new to FreeCAD and have looked only preliminarily at that workbench. Thank you for recommending it. However, after watching an introductory video ( https://www.youtube.com/watch?v=zErieb2E9VM ) covering the basics, I am not sure I can use it to get what I want.
It seems from my inexperienced standpoint (please correct me, as I am sure to be wrong) that dimensions created by the Techdraw workbench will not show in the 3D model, since the Techdraw workbench seems to only create dimensions in separate documents called (2D) "Pages". On this 2d-Pages, you can include "Views" of the model (to which then you can add Techdraw-style dimensions). So, it seems that I would not be able to use the Techdraw workbench to add dimensions directly to the 3D model. In fact, most of the Techdraw workbench's icons (including the dimension ones) remain inactive/grayed-out until you add a (2D) page (which is a separate document apart from the main 3D model). Only then you can add “views” of your model into the 2d-page, but dimensions applied to these “views” stay within the 2d-page document.
I am sure I am missing something. Please, help me understand how to use the Techdraw workbench to add dimensions to the 3D model.

[heda]

don't get the segmentation - is it a parametric model you have made or an imported stl?
if it is an stl, then there is nothing to do about segmentation (which is the reason why stl is not really a usable format for cad),
for a simple model like this - just remodel it from scratch in fc, so that you get proper geometries.
segmentation can also just be screen rendering, but then you should not have problems in selecting correct positions.

use Draft_Snap to get quadrant points to dimension from, assuming that it actually is a circular edge, and not a segmented edge that looks like a circle.

as for techdraw, it depends what one means with "3d model". If you want it in the model itself, then yes, draft/dimension is the right (and only) choice,
however, there are no problems in making a (static) 3d view in techdraw and dimension those Basic_TechDraw_Tutorial.

techdraw_3dview.png (61.42 KiB) Viewed 1011 times

oki, since I did not write exactly like it is, it indeed requires a bit of imagination and experimentation to find the correct properties (like prefix is really "override" (text), compare how they look like for a circular dimension and a linear dimension).
anyways, if you have the right quadrant points, all you need are the view-properties Draft_Dimension#View, just change them and see what happens, when you don't understand what a property does (after having changed it), then the wiki hopefully can shed some light over what that particular property should do.

[user1234]

Hello!

The outer circle in the tubular structure contains an odd number of segments (29 to be exact)

That is just the tessellation for visual representation. You can set each object the tessellation individual, or in Edit-->Perferences-->PartDesign-->ShapeView (only on new objects, on persist objects the settings do not incur). Do not set it to fine, because it can be quiet performance consuming.

Greetings
user1234

[mendy]

Hello
Attached is your example expanding on @heda's usebTechDraw method using your basic object done in Part Design and using Techdraw Workbench.

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[wisecad]

don't get the segmentation - is it a parametric model you have made or an imported stl?
if it is an stl, then there is nothing to do about segmentation (which is the reason why stl is not really a usable format for cad),
for a simple model like this - just remodel it from scratch in fc, so that you get proper geometries.
segmentation can also just be screen rendering, but then you should not have problems in selecting correct positions.

Heda,
Thank you so much for your newest post.
The tubular structure’s outer circle was a parametric model done in FreeCAD. Please, see image below, showing the sketch from which it was “padded”.

Software-Freecad-Issues-10-RelocatingDiameterDimensionLines-05-SourceScketchForPad.jpg (44.17 KiB) Viewed 899 times

I followed your advice, re-doing a simple model like this from scratch, and got exactly the same results. As it turns out, how many sides are used in a polygon representing a circle, has to do with factors affecting tessellation. Whether globally through the preferences used for the Part-Design workbench, or on a per-body basis, the Maximum-Deviation and Angular-Deflection parameters affect the tessellation, thus influencing the number of edges used in a polygon representing a circle. However, there seems to be other factors at play. Please, see User1234’s post and my reply for more detail.

By the way, I was already using Draft-Snaps while trying to add a linear dimension to the outer circle, but because of the odd number of segments representing the circle, I wasn’t able to choose two opposite points that would give me the exact dimension of the circle’s diameter but in a linear dimension format.

[wisecad]

That is just the tessellation for visual representation. You can set each object the tessellation individual, or in Edit-->Perferences-->PartDesign-->ShapeView (only on new objects, on persist objects the settings do not incur). Do not set it to fine, because it can be quiet performance consuming.
[/quote]

Hello User1234,
Thank you very much for your post. The Maximum-Deviation parameter (Edit-->Perferences-->PartDesign-->ShapeView) to which you referred me, was one of the factors affecting the tessellation process, hence influencing the number of edges used in a polygon representing a circle. By decreasing that number, I was able to get an even number of segments (48 to be exact), which allowed me to choose two opposite points to add a linear dimension to show the circle’s diameter. See the image below.

Software-Freecad-Issues-10-RelocatingDiameterDimensionLines-06-PreferencesPartDesignShapeViewMaxDeviationControlsTesselationEdgesOnRepresentationPolygon.jpg (82.07 KiB) Viewed 897 times

However, I also noticed that while keeping the Maximum-Deviation parameter fixed (in the PartDesign’s preferences), the length of the padding being applied also played a role in the tessellation, thus also influencing the number of edges used in a polygon representing a circle.

[wisecad]

Hello
Attached is your example expanding on @heda's usebTechDraw method using your basic object done in Part Design and using Techdraw Workbench.

Hello Mendy,
Thank you so much for your example using the TechDraw workbench to add dimensions to views of the model in 2D-pages. I must definitely pay more attention to the TechDraw workbench, although not being a professional my preference is to document as much as possible directly in the 3D model.

[user1234]

Hello!

By decreasing that number, I was able to get an even number of segments (48 to be exact), which allowed me to choose two opposite points to add a linear dimension to show the circle’s diameter.

It is just a visual effect. The edges and vertexes are not clickable or an object. You just hit it randomly precise enough.

Greetings
user1234