Misconception of Construction Line type in Fusion 360

[seyozenYTU]

As we know, Standard engineering drawing line types are specified by ISO 128. They represent different meanings on engineering drawing. Can be also seen on wikipedia

In Fusion 360,  short-dashed line (- - - - -) is used for representing the Construction Line! But, the conceptual meaning of dashed line is to represent hidden edges on engineering drawing according to ISO 128. Normally, Construction Line is used especially for symmetry line, revolve center-line or for creating non-profile sketches. 

This misconception causes some confusion on teaching or using the correct ISO meaning of the dashed line type used in engineering drawings. In Solidworks they use center-line for Construction Line. This can be acceptable for the use of center-line especially for symmetry line, revolve center-line representations.

Fusion 360 is a great white hope software for the sector. And the flagships of engineering softwares such as AutoCad/Mechanical/Inventor programs were created by the same owner: Autodesk. I think Fusion 360 programmers should exchange basic ideas on such issues. Because they support ISO, DIN etc. standards for years. I don't understand why most of new cad programs generally try to reinvent the wheel from the beginning.

Hope you improve this issue, guys!

[jhackney1972]

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@seyozenYTU wrote:

In Fusion 360,  short-dashed line (- - - - -) is used for representing the Construction Line! But, the conceptual meaning of dashed line is to represent hidden edges on engineering drawing according to ISO 128. Normally, Construction Line is used especially for symmetry line, revolve center-line or for creating non-profile sketches. 

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You are correct on the use of a short-dashed line as representing hidden edges in an engineering drawing, but Fusion 360 construction lines are used in "model sketches" not 2D drawings  The are, as you stated,  used in model sketches as symmetry lines, revolve center-line and especially for non-profile sketch entities.  Since construction lines are not used in the 2D drawing environment at all and short - dashed lines are use to represent hidden edges, it seems to me that Fusion 360 is following the ISO guidelines very nicely.

[seyozenYTU]

Thank you for your reply.

As I stated that it is a "construction line", so, i am aware of the difference between 2d drawing lines and sketch model lines. The fact that Fusion 360 uses "dashed line type" for representing the concept of symmetry line, revolve axis-line even in the sketch modeling. This is an obvious conceptual confusion! Because most of engineers know and use the conceptual meaning of "dashed-line" is for hidden edges in the technical literature. 

Let me give a suitable simile: we all know the representative meaning of pi (π). Does it make sense if I use pi-symbol to represent the edge length of a square in a formula? Then, the area formula teachings may be such as "a square area is calculated by π², guys".

This is what i'd like to point out here! This semester I have started to utilize Fusion 360 in my CAD teaching classes at the University. We teach 3D modeling and creating technical drawings documentation according to Mech. Eng. Standards in the course. Many of my students confused the Standard conceptual meaning between the center-line and the dashed-line in technical drawings thanks to Fusion 360 Construction line representation. 

There is no need to show the left ear with your right hand from behind! International Standard rules must be considered on such technical things in consistency for all modules in the software. This is only an humble constructive feedback for Fusion 360 dev. team. 

[andrew.de.leon]

Hi @seyozenYTU,

Sorry to hear your having problems with Fusion 360, but I’m very happy hear that you see Fusion 360 as the great white hope.

Before getting into this, I do just want to clarify that the design and drawing workspaces within Fusion 360 are separate workspaces. As a result, the design workspace does not adhere to drafting standards and was never designed with drafting standards in mind. However, the drawings workspace is quite the opposite — it currently adheres to ISO and ASME drafting standards. In terms of line types used within the drawing workspace, ISO drawings comply with ISO 128, ISO 129 and ISO 6410 while ASME drawings comply with ASME Y14.2.

You mentioned “Many of my students confused the Standard conceptual meaning between the center-line and the dashed-line in technical drawings thanks to Fusion 360 Construction line representation”, is this because they see line type no 2 used to represent construction geometry and line type no 1 used to represent axis of revolution and planes of symmetry within the design workspace before seeing line type no 1.1 for reference, hatching, screw thread roots, and line type no 1.2 for visible edges and outlines, and line type no 2.1 for hidden geometry, and line type no 4.1 for center lines? If I’ve misunderstood the issue, let me know.

Cheers, Andrew

[seyozenYTU]

Hi @andrew.de.leon,

Thank you for your reply.  Let's talk with figures, please see the attached image. In short, students had some problems understanding the ISO notional Line description because of the same dashed line representation for both hidden edges and construction line (used for symmetry) in Fusion 360. You can see an example of the misconception faced by the student in the attached image. Please consider that these students are learning with these ISO notions for the first time. And we use exactly the same ISO Standard materials for teaching given below.

According to ISO 128-24, Narrow Dashed Lines must be used for only hidden edges/outlines. If you use the dashed line type to describe a line/plane of symmetry even in sketch modeling, this coincides with the notation of Center-line (=Long-dashed dotted narrow line) in ISO 128. Because, only 0.4.1 line number is defined to describe a line/plane of symmetry. Yep, this Standard is created for Technical drawing rules, not for modeling/sketching for 3D, but why not use the same line notation both modules for sketching/modeling and drawing?

IMHO, Fusion 360 construction line should be replaced with ISO line number of 0.4.1.
Hope this explains my thesis! 🙂

dashed line described in ISO 128-24

Construction Line and Hidden edge confusion in 3D modeling view

[andrew.de.leon]

Hi @seyozenYTU,

Thanks for the details and confirming the issue. I've spoke to the wider UX team and we've added FUS-66030 to track the issue.

Just one more clarification, the image you shared comparing the front view in modelling to front view in drawings, the drawings image appears to be incorrect. Since the introduction of sketch visibility within drawings, normal sketch geometry (Continuous sketch line) is displayed using line type 05.1.1 and construction sketch geometry (Hidden2 sketch line) is ignored. I've attached a couple of images below from version 2.0.8335 (the latest update). Are you seeing the same, or something different?

Cheers, Andrew

[seyozenYTU]

Dear @andrew.de.leon,

Thank you very much for considering my proposal. I will eagerly track the issue.

Yes, there's no problem with sketch visibility within drawings, you are right! That's my fault, so sorry because I forgot to say that i had added some lines on the drawing view by Sketch Mode manually to show the similar appearance of construction line and hidden line type in different study modes. For clarify, please see added image-1.

And here i'd like to say that displaying the modeling geometry (Continuous sketch) lines in type 05.1 in drawing module is exactly the correct chosen type as described in ISO, thanks to dev-team. Hope to see the same importance to my beloved Construction Line type on design module 🙂

Here i can add one more important information for that is 05.1 line type scale should be adjusted according to geometry size. A possible problem can be seen on the added image-2. The 05.1 linetype scale should get smaller as the geometry size gets smaller. This can be solve by parameterizing the linetype scale to geometry (line, circle or spline segment etc.) size.

Thank you for your time.

With my best,

Image-1: using Sketch mode in Drawing moduleImage-2: ISO Line number 05.1 usage advise

[Anonymous]

It will be very nice if Fusion integrates this proposal with the coming updates. We want Fusion to be more robust and easy to use at the same time. I love using Fusion and the way the product development team listens to the customers. Nice job. Looking forward. 

[seyozenYTU]

Hi @andrew.de.leon,

Is there any news on the topic?

[seyozenYTU · Accepted solution]

Yess!

Finally we got the solution by the latest January 2021 Update. Thanks to all! @andrew.de.leon 

You can get more information from here.