Assembly 4 workbench

[aapo]

4. Now I would like to add a LCS "LCS_in_Model" to the model that I could then use to place the subassembly of the two cubes (or my crossbrace in reality) into a bigger assembly. After adding the LCS, I edit it but I can't select a reference (neither a plane, vertice, edge, nor a LCS from one of the parts:

I'm not sure if I understood you correctly, but you're supposed to connect parts together only LCS-to-LCS, using this button:

20200711_Asm4_connect_parts_button.png (24.31 KiB) Viewed 2654 times

screenshot

With that button you can choose which LCS you connect, and how to select the XYZ-permutations of the coordinates.

If you want to attach an LCS to a certain feature of your model, you should only attach an LCS within your part into that part; so don't try to attach an LCS of part A into part B. Instead, attach an LCS_A001 in part A to part A + attach an LCS_B001 in part B to part B; and then use the "move/attach a part" tool above. Select part A, press the tool, inside the tool select part B in the list, and then select LCS_A001 in part A list and LCS_B001 in part B list. Then, the parts magically connected, and stay together.

[WayofWood]

I'm not sure if I understood you correctly, but you're supposed to connect parts together only LCS-to-LCS, using this button:

That's clear and if you look into the 2cubes file the 2 cubes are connected by linking their "LCS_Test".

As long as everything stays within one assembly the workbench works flawless for me. What doesn't work for me is to use the 2 cubes as a sub-assembly in another model.

If you create a new file, create a new model and link the entire model from the "2cubes" into this file you no longer have access to the LCS of the individual cubes:

4Cubes.png (48.13 KiB) Viewed 2620 times

As you can see here if I have the 2 subassemblies in one file I can see the LCS of the individual cubes ("LCS_Test") but I can't use them to place the linked part.

I can use the LCS_in_Model in order to position my subassembly but within the model I don't have a possbility to link the LCS on the Model level to any part of the subassembly.

From my point of view there are three options:

(1) I still don't get the concept of A4 and I am doing sth wrong.
(2) The LCS of a linked part should be accessible on the model level so that it can be used to placement
(3) The LCS of a model could be somehow linked to a part of the model geometry or a LCS of one of the parts of the subassembly.

Best,
Oliver

[Zolko]

I can use the LCS_in_Model in order to position my subassembly but within the model I don't have a possbility to link the LCS on the Model level to any part of the subassembly.

you can attach the LCS_in_Model to an LCS_in_childPart with the Place_Datum command. Better yet, select LCS_in_childPart in the tree and click Import_Datum.

(1) I still don't get the concept of A4 and I am doing sth wrong.
(2) The LCS of a linked part should be accessible on the model level so that it can be used to placement
(3) The LCS of a model could be somehow linked to a part of the model geometry or a LCS of one of the parts of the subassembly.

(1) I have the feeling that you got that quite correct
(2) it's easy to say, quite easy to do, but it adds more levels of complexity and more ways of breaking things, more error-checking and more options, so I'm not favorable to that. Also, then people will want to use LCS in the sub-assembly of a sub-assembly, adding even more levels and more ways for breaking things
(3) this is a built-in FreeCAD limitation

[WayofWood]

you can attach the LCS_in_Model to an LCS_in_childPart with the Place_Datum command. Better yet, select LCS_in_childPart in the tree and click Import_Datum.

Thanks a lot! This was the missing bit of information. With an imported LCS the subassembly is easy to position in the overall master.

Best regards
Oliver

[uwestoehr]

I agree with Zolko's reasoning...

Ping

[Grawp]

I've gone through the official tutorials and examples and I'm slowly beginning to think that I've completely misunderstood ASM4.
I have basically following use-cases:

1. I place some thing in an enclosure to specific places and then I try modeling openings, mounting holes, and mounting brackets around them.
2. I want to draw some features which are not only additive but also subtractive at specific places in parent model.

Regarding 1. I'm starting to kinda succesfully manage it with heavy use of subshapebinders.
Regarding 2. I can't even do the additions..... I haven't figured out how to do an union and export of assembled things.

Anyway, back to my first sentence: I've looked through the examples and I also opened some models I found in this thread and it seems that nobody is even trying to do something like I'm trying to do and just use the ASM4 for visualization and animation.

Is it really what is ASM4 for? visualization and animation and nothing like doing somthing similar to this https://github.com/DeepSOIC/Lattice2/wi ... n-Tutorial ?

[WayofWood]

I've gone through the official tutorials and examples and I'm slowly beginning to think that I've completely misunderstood ASM4.

I think you are rather looking for features of the PartDesign workbench and other workbenches working with solids. An assembly is by definition when you put things together that you can disassemble again. So putting a board in a case would be an assembly but cutting holes in a case would be part of the "normal" modeling.

[Grawp]

I think you are rather looking for features of the PartDesign workbench and other workbenches working with solids. An assembly is by definition when you put things together that you can disassemble again. So putting a board in a case would be an assembly but cutting holes in a case would be part of the "normal" modeling.

Maybe the Lattice2 has been adding some weight to my confusion, because it is also working with LCSs (called Placements there). It is actually exactly what I need and I've used it many many times but it is missing a key feature and that is working across multiple files (or at least I haven't been able to persuade it to take App::Link as a regular PD body ).

[Zolko]

I'm slowly beginning to think that I've completely misunderstood ASM4.
...
Is it really what is ASM4 for? visualization and animation and nothing like doing somthing similar to this https://github.com/DeepSOIC/Lattice2/wi ... n-Tutorial ?

you have misunderstood the purpose of an assembly workbench. I can't help you there. Look at all the examples and you'll understand.

[ppemawm]

Is it really what is ASM4 for? visualization and animation...

Hardly.

Assembly4 facilitates the creation of numerous bodies using the PartDesign or Part workbench in the same or individual files then assemble and attach them in their proper location in 3D space. It also has the added benefit of simulating motion of an articulating or rotating assembly to check for proper operation during the design process.

If you have not seen these examples perhaps they will give you a better understanding:
https://forum.freecadweb.org/viewtopic.php?f=24&t=48473