Series of articles about the pitfalls of parametric editing

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NormandC
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Series of articles about the pitfalls of parametric editing

Postby NormandC » Sun Nov 03, 2013 8:26 pm

I just came upon this series of articles about the inherent fragility of parametric modeling, I think it's an interesting read.

It is from Evan Yares, the same blogger (a CAD industry long timer) who wrote the "CAD usability sucks" series last year. He sure seems to like controversial titles! ;)

Rather than discard parametrics altogether in favor of a direct modeling approach, he suggests a new modeling strategy which can be applied to most parametric CAD packages. He does not give much info about it though, I don't know if the guy who came up with it plans to monetize it somehow. I was able to get a PDF of his presentation at Solid Edge University, but I haven't read it yet.

The failed promise of parametric CAD part 1: From the beginning
The failed promise of parametric CAD part 2: The problem is editing
The failed promise of parametric CAD part 3: The direct solution
The failed promise of parametric CAD part 4: Going horizontal
The failed promise of parametric CAD part 5: A resilient modeling strategy
A Resilient Modeling Strategy - Solid Edge University
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sliptonic
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Re: Series of articles about the pitfalls of parametric editing

Postby sliptonic » Mon Nov 04, 2013 5:06 am

Interesting read indeed. Is the pdf one you can share?
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NormandC
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Re: Series of articles about the pitfalls of parametric editing

Postby NormandC » Mon Nov 04, 2013 5:08 am

The pdf is already linked, it's the last one.
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Re: Series of articles about the pitfalls of parametric editing

Postby jriegel » Mon Nov 04, 2013 8:44 am

Very good approach. It shows clearly that parametric has its pitfalls. My company too has a model schema guide.
I think when FreeCAD is more mature it makes sense to define one too.
Stop whining - start coding!
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Re: Series of articles about the pitfalls of parametric editing

Postby sliptonic » Mon Nov 04, 2013 2:44 pm

normandc wrote:The pdf is already linked, it's the last one.
Doh! :oops:
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NormandC
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Re: Series of articles about the pitfalls of parametric edit

Postby NormandC » Sun Jan 19, 2014 9:45 pm

I just found that there is now a video. It's mostly the same content as the PDF, but it's interesting that early on, it shows an example of bad modeling, then how to model it in a more robust manner.

http://resilientmodeling.com/V3_RMS_Groups_Video.html
Edit 2015/01/20: the website was changed, there is not a single video anymore but a series of them. You can browse the site here: http://resilientmodeling.com

If you are wondering like I was what an ECO stands for, it's Engineering Change Order.

Some of the advice cannot be applied to FreeCAD at the moment, but maybe with the PartDesign Body merged to master that will change.
Last edited by NormandC on Wed Jan 21, 2015 2:45 am, edited 1 time in total.
Reason: Fixed link, they changed the website layout...
arcol
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Re: Series of articles about the pitfalls of parametric edit

Postby arcol » Sat Feb 01, 2014 8:14 am

Hi,

I tried to replicate the demo modell (what is showed in the video), but I stuck.
Is there anyone succeed?

I know it is a general concept and I'm trying to copy a specific example,
but still would be nice to replicate the almost same project tree as shown on the presentation.

Update:
I stuck at the "Tombstone 12mm wide" step.
Here is where I'm:
rms.png
stuck at tombstone:-\
rms.png (144.66 KiB) Viewed 3286 times
Update2:
Ok.
Tombstone: check:)
Obligatory pic:
rms_tombstone.png
Tombstone
rms_tombstone.png (98.83 KiB) Viewed 3284 times
Now I stuck at the "Replace face" feature. Cant find it.

I'm pretty sure it is the "removeSplitter()" python function:

Code: Select all

head_thread = head.fuse(shaft_unthreaded).removeSplitter()
For those who want to proceed, here is the 3D model:
rms.fcstd
Resilient Modelling Strategy
(116.81 KiB) Downloaded 65 times
Last edited by arcol on Sat Feb 01, 2014 3:57 pm, edited 1 time in total.
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Re: Series of articles about the pitfalls of parametric edit

Postby arcol » Sat Feb 01, 2014 3:46 pm

Update3:
(sorry only 3 attachment/post allowed).

This is where I'm:
rms_rib.png
After the rib step
rms_rib.png (149.08 KiB) Viewed 3278 times
This is what I can't do:
rms_extend_boss.jpg
Extend boss
rms_extend_boss.jpg (67.72 KiB) Viewed 3278 times
Any idea? Maybe the loft feature?

Ok, I gave up. If anyone wants to continue, play with, I uploaded the latest model I have. Have fun!
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Re: Series of articles about the pitfalls of parametric edit

Postby kwahoo » Sat Feb 01, 2014 4:57 pm

Hi arcol!

It's hard to replicate the video without "Body" container. Unfortunately the "Body" is not implemented in the master FreeCAD so far, only in the "assembly" branch. In your file cylinders and rest of model aren't connected with each other. You do boolean fusion and them add a pad on cylinder planar face.

PS I dissagre with some statements from the video, as size in feature name, "3.99" radius thing and especially "replace face" - what kind of sorcery is this? ;)
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NormandC
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Re: Series of articles about the pitfalls of parametric edit

Postby NormandC » Sat Feb 01, 2014 6:24 pm

arcol wrote:Now I stuck at the "Replace face" feature. Cant find it.

I'm pretty sure it is the "removeSplitter()" python function:
No it isn't. removeSplitter() is the algorithm behind the "Part --> Refine shape" menu tool. When doing boolean operations, the OCC kernel leaves residual edges. removeSplitter() cleans those edges by joining coplanar faces.

The video shows a work flow specific to Solid Edge. The author of the Resilient Modeling Strategy is a Solid Edge reseller. The method appears sound and may be useful in FreeCAD, but as jriegel said, we will have to customize it to FreeCAD's workflow.

FreeCAD currently does not have a tool similar to Solid Edge's Replace face tool.
kwahoo wrote:especially "replace face" - what kind of sorcery is this? ;)
"Replace face" is a very useful tool that I've used quite a few times. I certainly hope that something similar gets added to FreeCAD in the future. But it may require some complex coding!
kwahoo wrote: It's hard to replicate the video without "Body" container. Unfortunately the "Body" is not implemented in the master FreeCAD so far, only in the "assembly" branch.
I for one can't wait for jriegel to merge the assembly branch into the master branch. it will be "soon"... (but the assembly itself will be disabled as it's not fully usable at the moment and will see considerable changes)

Right now and for the past few months I've refrained from posting any elaborate video tutorials, knowing that with the Body container and working planes, the Part Design work flow will drastically change. All of the current FreeCAD videos focusing on Part Design found on YouTube will basically be obsolete.