Feature Request: Threads

[wandererfan]

Enclosed please find my file for better understanding ...

Not really sure how to handle this. The geometry of the threads isn't in the model so there's nothing for TD to draw. Might have to wait for the "drawing on the drawing" functionality to finally get implemented. Or maybe select some edges in the drawing and press "add threaded hole".

You can play with adding a helix to the model, but it isn't entirely satisfactory.

[ulrich1a]

Not really sure how to handle this.

It is some time ago since I had a look into this topic. Step-files support a property of a cylindrical surface, that this surface represents a thread. The shown geometry is nothing more than a cylindrical surface. In cases it may be decorated. But it is only an additional information, that will be used in certain cases. I would expect something similar in FreeCAD, that we can link to a cylindrical surface a thread property. The view provider could than decorate such a surface with thread-texture. The TechDraw Workbench could than add the required lines, in order to show the thread property in drawings according to drawing standards.

As far as I know, such a linkable property, that would indicate a thread on a cylindrical surface does not exist in FreeCAD. Without such underlying framework, it is nearly impossible to support this request. So the first step is to create such a property, that can be applied to cylindrical surfaces. Based on this further functionality can be added:
- view provider for this property
- task menu to set this property
- export and import of the thread property into step-files
- presentation of threads in drawings according to the standards like ISO 6410-1:1993

The following link gives an introduction to simplified thread representation in drawings in section 10: http://web.iitd.ac.in/~achawla/public_h ... s/sp46.pdf

Ulrich

[reox]

As far as I know, such a linkable property, that would indicate a thread on a cylindrical surface does not exist in FreeCAD.

I'm no expert in how the hole feature is implemented in PDN but all the properties of the thread are stored in there. Or not?

[ulrich1a]

I'm no expert in how the hole feature is implemented in PDN but all the properties of the thread are stored in there. Or not?

Yes all needed data are in the hole object. But they are not available in the shape data, which are used in TechDraw. So following this approach, TechDraw would need to search for every cylindrical hole in the shape data, if there exist an corresponding hole object in the feature tree. It is not possible from the shape data alone, to decide if an cylindrical hole is just a subtractive feature or a hole feature. What makes it more complicated, is that the 3D-location of the hole may not directly contained in the hole object, but only indirectly from the linked sketch.

So it could be done this way, but as a programmer, I would want another solution.

Ulrich

[reox]

I'm no expert in how the hole feature is implemented in PDN but all the properties of the thread are stored in there. Or not?

Yes all needed data are in the hole object. But they are not available in the shape data, which are used in TechDraw.

Okay, thanks for the information! I probably should look more into the technical details of freecad, but free time is rather sparse right now :/

[wandererfan]

Yes all needed data are in the hole object. But they are not available in the shape data, which are used in TechDraw. So following this approach, TechDraw would need to search for every cylindrical hole in the shape data, if there exist an corresponding hole object in the feature tree. It is not possible from the shape data alone, to decide if an cylindrical hole is just a subtractive feature or a hole feature. What makes it more complicated, is that the 3D-location of the hole may not directly contained in the hole object, but only indirectly from the linked sketch.

TD also knows what objects the Shape(s) come from. Is there something in the Body that says "I contain hole features", or would I have to look through all the PD::Features in the Body's history to find the hole features?

[maker]

Meanwhile we have FreeCAD release 0.18.15998.
Could any progress and improvements be achieved in the subject normative correct presentation of threads in Techdraw?

[NormandC]

Meanwhile we have FreeCAD release 0.18.15998.

No, we do not. 0.18 is not released yet; the revision count is now at 16027 and is still in development.

Could any progress and improvements be achieved in the subject normative correct presentation of threads in Techdraw?

Probably.

[maker]

@NormandC
What a pity!
Possibly priorities in development are on other things focused...

[NormandC]

maker, have you actually bothered reading the previous replies in the topic?

Here, let me point you to the relevant one: https://forum.freecadweb.org/viewtopic. ... 10#p251462

This is not an easy matter. It will take time before this is implemented. None of the FreeCAD developers except one are paid to work on FreeCAD. They work on it in their free time. The one who is (only partly) funded works on the Arch/BIM workbenches.

Until a developer comes in with the knowledge and the willingness to work on this, the situation will remain as it is. No amount of complaining will change this fact.