V0.19 Top Down Assembly Design Using Assembly4--Update #11

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fjush
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Re: V0.19 Top Down Assembly Design Using Assembly4--Update #10

Postby fjush » Sat Nov 14, 2020 10:19 am

I am interested in top down design methodology in freecad using assembly4 workbench, are you willing to share on of your models? I'd like to investigate model tree step by step. I use topdown skeleton method in work using catia and i wonder how big of a gap is between commercial software and freecad, i am looking for a CAD software for hobbyistic use.
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ppemawm
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Re: V0.19 Top Down Assembly Design Using Assembly4--Update #10

Postby ppemawm » Sat Nov 14, 2020 12:02 pm

Donatello wrote:
Sat Nov 14, 2020 1:42 am
Could you if you are agree with that bring some pictures of your great work to the Wikimedia FreeCAD page.
Thank you for your kind comments.
You may use any of the images as you wish but perhaps you may want something a little more modern:
https://forum.freecadweb.org/viewtopic.php?f=24&t=51054
"It is a poor workman who blames his tools..." ;)
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ppemawm
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Re: V0.19 Top Down Assembly Design Using Assembly4--Update #10

Postby ppemawm » Sat Nov 14, 2020 12:08 pm

fjush wrote:
Sat Nov 14, 2020 10:19 am
...are you willing to share one of your models?
Yes, of course. Please contact me via personal message for a download link.
I would appreciate your feedback on how the methods can be improved.
"It is a poor workman who blames his tools..." ;)
freedman
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Re: V0.19 Top Down Assembly Design Using Assembly4--Update #10

Postby freedman » Sat Nov 14, 2020 3:20 pm

Excellent work as always.
Question: I do a lot of "here is what we have" can you package it in this space. Then I go and try a few things and present a model concept, that might be manufactured for a year or so until we want to modernize. So I'm not necessarily doing a complete redesign just a bunch of machined component changes.

Do you feel that your current modeling approach is the best for modeling existing parts and making a large number of changes to what we call the master sketch or early created parts?
Thanks
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ppemawm
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Re: V0.19 Top Down Assembly Design Using Assembly4--Update #10

Postby ppemawm » Sat Nov 14, 2020 5:10 pm

freedman wrote:
Sat Nov 14, 2020 3:20 pm
Do you feel that your current modeling approach is the best for modeling existing parts and making a large number of changes to what we call the master sketch or early created parts?
I do think that using a master sketch and carbon copies for each body is a good approach to control design intent and critical interfaces. It also dramatically improves sketch productivity. Now, whether or not you expand master sketches to include a sub-assembly or the top-assembly probably depends on what and how you model.

A master sketch can serve as an assembly solver for moving parts, for example. Also, if your assembly interfaces are fixed due to an interchangeability requirement in form, fit, and function for legacy components (spares, for example) then it could be quite useful to use an assembly master sketch to control those interfaces.

It also depends on how you set up the master sketches (simple, but not too simple) and what kind of changes you expect. Master sketches and carbon copies cannot tolerate major changes that affect the number of sketch vertices or edges without breaking the model or assembly that depends on it.

In any event, Assembly4 is quite simple with no unnecessary frills and it nicely facilitates several different approaches to assembly design. Remember that if you use Assembly4 you do not have to use a master sketch for the assembly especially if you assemble as you design. That way you can still work in-context either in the top-assembly or sub-assembly files.

I am moving away from using master sketches for the top assembly, preferring them only for the bodies. Please note that some of my use of master sketches for assemblies is a hold over from in-context assembly design before there were any assembly workbenches that accommodated a top-down approach. As with any thing else in FreeCAD there is always more than one way to skin the cat so who's to say what's best.
"It is a poor workman who blames his tools..." ;)
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ppemawm
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Re: V0.19 Top Down Assembly Design Using Assembly4--Update #11 Exploded Views

Postby ppemawm » Sun Nov 15, 2020 5:40 pm

Zolko recently added a couple of enhancements in Assembly4 V0.9.11 that nicely facilitates exploded views so I could not resist adding this image to this thread. The enhancements significantly improve the "move/attach a part in the assembly" dialog. They also allow you to capture spreadsheets of various configurations including a function to toggle among the various configurations.
(See also https://forum.freecadweb.org/viewtopic. ... 10#p447976)

Capture_exploded.JPG
This is an example of an exploded view in both the sub-assembly of wheel and tire as well as the top-assembly.

The original assembly configurations can be easily viewed by selecting the appropriate spreadsheet and then right click Assembly > Restore Configuration. The various configurations are saved in a folder in the assembly model as highlighted above in the Combo View.
Capture_exploded.JPG (234.12 KiB) Viewed 307 times
"It is a poor workman who blames his tools..." ;)