[solved] exploding STEP compound: slow and flattens the object hierarchy

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eudoxos
Posts: 33
Joined: Tue Jul 19, 2016 4:14 pm

[solved] exploding STEP compound: slow and flattens the object hierarchy

Post by eudoxos »

I sometimes receive a whole assembly as STEP, then would like to explode it (perhaps delete some parts and so on). Explode compound is very slow in FreeCAD when the compound has many components, I actually often think that FreeCAD died...

For example this one https://grabcad.com/library/nema-17-v-s ... or-500mm-1 has 16k parts when exploded and the whole process takes tens of minutes. I am actually not interested in all those small parts, and I assume the object has internally some hierarchy (such as the nema17 motor, the extrusion, the moving part, each with their internal parts) but the result in FreeCAD is flat. That makes the result less useful for selecting/manipulating sub-parts.

If I use compound filter, OTOH, then even with rather wide selection (e.g. length window with maximum range, from 0.01% to 100%), the result is shown immediately; in that case, of course, I don't see the constituents and cannot select/delete them manually. I can explode the filtered result, though, which helps a bit already, and it is quite fast, even with about 1.4k components.

So the questions are:
  1. can I decompose the compound only at the first level, without flattening as explosion does?
  2. Some tricks (besides filtering and subsequent explosion) to make the process faster?
  3. Any way to preserve meaningful names/labels (I assume they are in the original compound) rather than auto-numbering?
Thanks!
Last edited by eudoxos on Thu Apr 09, 2020 4:00 pm, edited 2 times in total.
kisolre
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Re: exploding compound: flattens the object and is very slow

Post by kisolre »

Uncheck this (Edit/Preferences) and then import the STEP:
.
StepCompoundMerge.JPG
StepCompoundMerge.JPG (102.43 KiB) Viewed 1574 times
eudoxos
Posts: 33
Joined: Tue Jul 19, 2016 4:14 pm

Re: exploding compound: flattens the object and is very slow

Post by eudoxos »

kisolre wrote: Thu Apr 09, 2020 8:25 am Uncheck this (Edit/Preferences) and then import the STEP:
WOW, that actually worked. Names are still numerical, but I can live with that; the complexity is greatly reduced. Thanks!
evg-zhabotinsky
Posts: 2
Joined: Sat Oct 16, 2021 7:44 am

Re: [solved] exploding STEP compound: slow and flattens the object hierarchy

Post by evg-zhabotinsky »

Thank you so much, you just saved me from Fusion 360! xD

I'm a complete newb to CAD software. (Unless you count some OpenSCAD, which is more like programming.)
Just viewing a .step file is such a basic usecase, possibly one of the first interactions with FreeCAD for many users.
And when you get a seemingly useless single object upon opening the assembly file... Quite demotivating.

P.S. It seems the default behavior (combine everything) cannot be restored without deleting FreeCAD config file.
And even just pressing "Apply" anywhere in settings (after importing a .step) disables auto-compounding!
It seems this feature is more broken than it seemed to be. But I don't mind, it is stuck on the "good" behavior! xD
chrisb
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Posts: 53933
Joined: Tue Mar 17, 2015 9:14 am

Re: [solved] exploding STEP compound: slow and flattens the object hierarchy

Post by chrisb »

evg-zhabotinsky wrote: Sun Oct 17, 2021 6:30 pm I'm a complete newb to CAD software. (Unless you count some OpenSCAD, which is more like programming.)
Just viewing a .step file is such a basic usecase, possibly one of the first interactions with FreeCAD for many users.
And when you get a seemingly useless single object upon opening the assembly file... Quite demotivating.
Others want exactly that: a single object as base for further modeling. It is obviously not possible to satisfy all needs, so it is configurable. You shouldn't get so easily demotivated, if you want to learn a new parametric CAD software.
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