how to make a parametric profile?

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fponticelli
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how to make a parametric profile?

Post by fponticelli »

I draw the v-slot profile and I'd like to make it parametric so that I can change its length by changing one parameter. Right now I have several shapes extruded and subtracted and I have to change each extrusion length individually. Any way to make it more smart?

Here is the file I am working on: https://github.com/fponticelli/smallbri ... er/freecad
wmayer
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Re: how to make a parametric profile?

Post by wmayer »

At the moment this is not possible. There is some work in progress on an expression engine which allows you to work with formulas.
jmaustpc
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Re: how to make a parametric profile?

Post by jmaustpc »

fponticelli wrote:and I have to change each extrusion length individually
All you have to do in the exact example you have provided is to multi select all the Part Extrudes (cntrl click in treeview) and then adjust the extrude value ....you may possibly need to click manual recompute (the arrows left of the workbench switcher) if the icon is not greyed out i.e. the arrows are blue.

Then all the extrudes will adjust to that same new value, at the same time.

personally I would have modelled the whole thing differently in this specific example. i probably would have used sketches and PartDesign. Depending on the profile, either one complex sketch or a more simple set of sketches and PartDesign Patternfeatures.

Jim
fponticelli
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Re: how to make a parametric profile?

Post by fponticelli »

Thanks for the quick advices and I really look forward to the expressions, it sounds like an awesome feature.

About using sketches I tried and failed ... the constraints got either too slow or crashed the app entirely but I guess I was stressing the constraints too much. Also even if I succeed, will it not require multiple "subtract"?

On the same note, would it be possible to create an extrusion directly with the holes?
jmaustpc
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Re: how to make a parametric profile?

Post by jmaustpc »

fponticelli wrote:Thanks for the quick advices and I really look forward to the expressions, it sounds like an awesome feature.
Yes it will be, see this topic if you want to compile a development version and help test it.
fponticelli wrote:About using sketches I tried and failed ... the constraints got either too slow or crashed the app entirely but I guess I was stressing the constraints too much. Also even if I succeed, will it not require multiple "subtract"?

On the same note, would it be possible to create an extrusion directly with the holes?
As you have found, in theory you can make it from one sketch ... but it would be a very complex sketch....and hence unlikely to be a good idea.

What version of FreeCAD are you using, please post your Help about FreeCAD data.

You could make this in several ways. If using sketches you could make one for the outer shape and the make others and to pocket the details and then use PartDesign Polar Pattern features.

In your first post you asked how to adjust the lengths on the Extrusions ...as I said if you just select them all at once with the control button, you can adjust the extrusion length property once and all the selected extrusion will update to the same value.

You could also make a face and then extrude just that face with one extrude.

Also you need to think about what you want these for, as they are very complex they may make a whole model very slow if you use a lot of them directly in a complex model. For a complex model if it becomes unmanageably slow, you may find it better to model each piece in a different FreeCAD file and create a "simple copy" or export a STEP file from the result and then assemble the components in a separate FreeCAD project.
kusi
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Re: how to make a parametric profile?

Post by kusi »

in the meantime, is there a possibility to have a parametric extrusion length?
drmacro
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Re: how to make a parametric profile?

Post by drmacro »

kusi wrote: Thu May 25, 2023 12:22 pm in the meantime, is there a possibility to have a parametric extrusion length?
Expressions, spreadsheet with configuration table, and more have been available for quite some time.

...yes
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mhalil
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Re: how to make a parametric profile?

Post by mhalil »

FreeCAD - Intro to Parametric Modelling;
phpBB [video]
Attachments
parametric.png
parametric.png (149.46 KiB) Viewed 467 times
v-slot-profile.FCStd
(107.5 KiB) Downloaded 6 times
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