Naming of FreeCAD entities

[davidosterberg]

Well, naming is certainly not a strength of FreeCAD. Comparing to most other CAD software, FreeCAD Body is more of a Part, while the multi-solid support I am aiming for is kinda equivalent to multi-body in other CAD.

Indeed. It all seems very silly in retrospect. Everything is named wrong! Part (WB), Part (container), Draft (WB). And if your changes to PD gets merged: PartDesign, and Body. Unfortunately I doubt that there is willingness to correct this mess.



Edit:
In order to converge on a consensus proposal. I created this table. It is a work in progress. I will update it with your comments

[Jee-Bee]

You forgot the naming between part and part design (extrude vs pad)

[wsteffe]

FreeCAD Body is more of a Part, while the multi-solid support I am aiming for is kinda equivalent to multi-body in other CAD.

Yes, please let fix at least this naming: Body >> Part, Part >>Assembly. This missnaming generates a big mess.
I remember a long discussion in which I was saying that it doesn't make sense to have separate histories for different bodies in a part. RT, you did not agree with my view but now I may understand that it was just because with the term Bodies you actually was meaning Parts.
Of course it is perfect to have separate histories for differtent Parts. This is done in all CADs.

Let imagine that the developer of new CAD chooses to exchange the name Solid into Surface, Surface into Edge ...
The software would work as well, but I think that nobody would want to use it.
This stupid example is just to say tha the naming conventions are important. We need to use a common language ..

In my opinion the FC naming problem should be dealt as a very serious bug, not as a simple annoyance.

[chrisb]

I fully agree that the Part container would have better been called "Assembly" for three reasons: 1) it actually is an assembly and sensible to be used only if there are more than one thing in it. 2) The notion "Part" occurs so often with different meanings that renaming one of them is already an improvement. 3) It would be clearer for newbies that they don't need such an entity for a simple model with only one body in it.

However: I don't know what the future brings, but one major task is to have assemblies in the core system. The naming shouldn't cause any problems then.

I am very unsure about renaming "Body" to "Part" for the same reason mentioned above: The notion is used so liberally in discussions and the documentation that we have to assure that nothing else could be meant than what is called nowadays a "Body". The latter is excellent for distinguishing it from other entities, a "Part" (currently!) is not.

[wsteffe]

I am very unsure about renaming "Body" to "Part"

But once you have renamed "Part" to "Assembly", it goes automatically that "Body" has to become "Part":
In all the CAD systems an Assembly may be an "Assembly of Parts" or an "Assembly of SubAssemblies" (that is a higher level Assembly).
I have never seen a CAD system in which you may put a Body directly in an Assembly.
In example a Body in Catia is always a Solid and it may be defined only inside of a Part.

In FC to make an extrude with the "Part Design WB" you must have already defined a Body.
In Catia to make an extrude (called Pad) with the "Part WB" you must have already defined a Part object.
A Catia Part is indeed equivalent to what is (wrongly) called "Body" inside of FC.

[Jee-Bee]

First i think we have to split this off from the original topic!

Second. As long as FC is able to construct a part hierarchy. the naming is not that importand to me. on feature level or WB level i think it is more important.
MAin reason for this is that what a part is or an assembly is is very dependend on perspective. I try to show this with two situations:

• I make a product of multiple objects(keep it general) some objects are multiple abject assembled to a new one. But basically all objects i need are made of a single material.
• Now i make a product of multiple objects but the situation is a bit different. For example i buy a sensor for something and some processing board. For me within my structure it are single parts. but for their manufactures it are assemblies. But even a resistor within the sensor is basically a assembly for their manufacturer.

For example NX only knows parts they use it for everything even for a drawing.

In my opinion the biggest problem is not the current naming convention of body, part, assembly... For me is the biggest problem that if somebody is talking about part or a part that is unknown if he is talking about a part that he is creating OR that he is talking about the partWB

[davidosterberg]

@Mods, feel free to move to its own topic. I know this has been discussed before (not leading to anything). But it is so fun that we might as well discuss it again

[wsteffe]

The latter is excellent for distinguishing it from other entities, a "Part" (currently!) is not.

I think that it is just the opposite:

The "Part" was introduced in CAD world more than 50 years ago. Today it is used with a very precise meaning in all CAD systems.

The "Body" concept instead was introduced more recently by the so called multi-body CAD systems.
In example, it was only a couple of years ago (I think with with the release of Creo 5.0) that the multi-body capability was introduced in
the PTC Creo product.

The exact meaning of "Body" may change from CAD system to CAD system. In example in Catia it is substantially equivalent to a Solid.
In ZW3D, which is still a multibody CAD system, the term Body is not used at all. In ZW3D a Solid is just called a Solid.

[wsteffe]

First i think we have to split this off from the original topic!

Hello JB, may you take care of the splitting off ?. I do not know how do do it.

that a part is or an assembly is is very dependend on perspective.

I agree in priciple that the CAD document associated with a product may be organized in different ways depending on the perspective.
I do undersatnd very well what you are saying about the board and its components (your perspective is different than the perspective
of the component manufactuer). I am working on the same technical area.

But I never intended to tell if something should be defined as Part or as an Assembly in a given project.
I was just saying that, in the frame of mechanical CADs, there are many technical terms which are universally accepted.

the naming is not that importand to me

You may decide to call things differently but, if you want to comminucate with other experts in the fields, it is much better if you use the standard terminology. Previously you have mentioned a Board, a Resistor and a Sensor. I inderstood what you mean because these techical terms have a precise meaning.

Why do you think that using proper names is not important also when speaking about CAD concepts?

[Jee-Bee]

We are not aloud to split the topic, we have equal rights...

I don't think (except here) anny discussion about the the type of name that's used for CAD models.
In my work we call it mostly dependend on the physical state we do something with it. Most of the time thes two names are probably equal but not always. In CAD an it be a assembly but were talking about parts and sometimes reversed too.
Don't forgot that the structure as in CAD isn't neccasary the same structure in real live. for example if i have a breacket that is assembled in something. the bracket is mounted to 4 other objects and in total 11 screws + rings + bolds. i can choose the make this set a own level (probably without drawing) while it physically not.

Also the examples i used specially the sensor is funny because both the CCD as the whole camera are sensors depends on where used!
Another funny thing. I have worked for a company that makes sensors of the size 8 [m] x 4 [m] x 4.5[m] and this sensor was able to look between 5 [km] and 2000 [km].