Assembly 4 workbench

[HelloWorldXD]

Hello,

i have a question.
i assembled some parts with ASM4, this works by the way great (after a few try an errors)
But then i have to make a new cut in one of the assembly parts and the hole assembly fall apart.
The LCS References have changed. I have manually changed again the LCS position and the assembly refreshed correct.
Have i done something wrong? or is this a problem because of topological naming?

i think the idea behind asm4 is great Screws for example are very quick installed (quicker than in Solid Edge or Catia).
When i changed a feature that is in the part for example a extrusion length the assembly update correctly but when i make a new feature (Hole or somethink) the LCS changes.

Thanks for the help

[racemaniac]

Hello,

i have a question.
i assembled some parts with ASM4, this works by the way great (after a few try an errors)
But then i have to make a new cut in one of the assembly parts and the hole assembly fall apart.
The LCS References have changed. I have manually changed again the LCS position and the assembly refreshed correct.
Have i done something wrong? or is this a problem because of topological naming?

i think the idea behind asm4 is great Screws for example are very quick installed (quicker than in Solid Edge or Catia).
When i changed a feature that is in the part for example a extrusion length the assembly update correctly but when i make a new feature (Hole or somethink) the LCS changes.

Thanks for the help

That's the infamous FreeCad topological naming issue. The names of faces/edges/vertices can change randomly when making changes to objects, and if you connected other objects to those faces/edges/vertices... you're out of luck. (which makes the second tutorial maybe a bit misleading. using its methods will quickly lead to issues with topological naming)

For now the main advice seems to be to as little as possible connect directly to features of the models.

Let's hope FreeCad will soon get a fix for this issue, since it affects far more than just Assembly4

[neunR]

What do you think, can this work ? Unfortunately I don't have the time to test, but I'd be happy to hear back from your experiments.

With your hints I was able to get the animation to work:



I had to use some intermediate variables for the calculations to keep the angle & displacement expressions manageable.
Is there a way to make expression a bit more readable? i.e. indentetion

All the files and documentation is in this gitrepo: https://github.com/9R/angleBarLamp

Thanks for the help & keep up the great work

Just as a sidenote: It would be a great feature in a future assembly4 version, if you could add a slider to the animation dialog to quickly jump to different steps within the animation range.

[dubstar-04]

What do you think, can this work ? Unfortunately I don't have the time to test, but I'd be happy to hear back from your experiments.

With your hints I was able to get the animation to work:

That is amazing!

[dxp.dev]

Do you consider adding the possibility to animate the assembly with more than one variable ?

[ppemawm]

With your hints I was able to get the animation to work:

Well done.
Thanks for sharing your file. I appreciate your use of nested conditional statements!

This is an excellent example of using Assembly4 for bottom-up assembly, not requiring a master sketch.

Could you add some detail about how you went about your modelling and assembly process, especially how you attached the LCS's?

[ppemawm]

The LCS References have changed. Have i done something wrong? ....or is this a problem because of topological naming?

Yes.
One preferred method is to use a master sketch of the assembly.

Create LCS's in Model and attach only to the mastersketch edges or vertices. Then you can attach the Part LCS to
the Model LCS. Make sure that the Part LCS is attached only to origin planes. This will allow you to change features in the Parts without affecting the assembly.

However, if you change or add any master sketch geometry (edges or vertices) you will likely run into the same topological naming problem. You should be able to change master sketch dimensional constraints without a problem, i.e. animate the mastersketch.

[Zolko]

The LCS References have changed. Have i done something wrong? ....or is this a problem because of topological naming?

One preferred method is to use a master sketch of the assembly.

I think an explanation of best practices on how to use master sketches would be very useful. Would you have time to write something about that ?

[racemaniac]

You should be able to change master sketch dimensional constraints without a problem, i.e. animate the mastersketch.

I'm wondering how true this is. When playing around with Assembly4, i created a simple sketch that simulated steering (basically a rectangle with 2 lines sticking out of it resembling he wheel axles). When animating that, i already ran into the topological naming issue >_<. So i'm afraid even with simple sketches it can quickly go wrong when animating :s...
Topological naming is really a huge achilles' heel for FreeCad atm .

[ppemawm]

ppemawm wrote: ↑
Thu Feb 20, 2020 11:38 am
You should be able to change master sketch dimensional constraints without a problem, i.e. animate the mastersketch.

I'm wondering how true this is.

True indeed.

Please see numerous examples in this Assembly and Users Showcase Forums, such as:
https://forum.freecadweb.org/viewtopic. ... 20#p361030 and
https://forum.freecadweb.org/viewtopic. ... 71#p362653

If you can share your file I would be interested to see what problems you are having with this approach.