Misalignment on polar pattern?

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naasking
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Joined: Tue Sep 28, 2021 12:28 pm

Misalignment on polar pattern?

Post by naasking »

OS: Windows 10 Version 2009
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24291 (Git)
Build type: Release
Branch: releases/FreeCAD-0-19
Hash: 7b5e18a0759de778b74d3a5c17eba9cb815035ac
Python version: 3.8.6+
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/Canada (en_CA)

I created a padded sketch for a bridge across a gap and the top of the pad is flush with the top. I then applied a draft to one of its faces to get a downward angle on the bottom face. I then applied a polar pattern for this feature but the "replicated" items have different dimensions. You can see from the image that the height is different which produces a gap so they're no longer flush with the top ring. Did I do something wrong here?

Edit: I would also add that chamfers and fillets on that bridge failed which is why I tried the draft. I haven't been able to figure out a consistent rule for when they will work or fail, so if anyone has some insight that would be appreciated too!
Screenshot 2021-10-26 082332.png
Screenshot 2021-10-26 082332.png (45.41 KiB) Viewed 982 times
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Fan cooling duct v2.FCStd
(145.68 KiB) Downloaded 18 times
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Shalmeneser
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Re: Misalignment on polar pattern?

Post by Shalmeneser »

You need at the end to PolarPattern002 with Pad003+Draft.
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Capture du 2021-10-26 18-38-37.png
Capture du 2021-10-26 18-38-37.png (27.51 KiB) Viewed 934 times
chrisb
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Re: Misalignment on polar pattern?

Post by chrisb »

Fillet, Chamfer and Draft are rather dressups, and as such the patterns need the feature which is dressed up as well.
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Shalmeneser
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Re: Misalignment on polar pattern?

Post by Shalmeneser »

Code: Select all

 └ Body001 (Body)
    ├ Revolution (Revolution)
    │  └ Sketch005 (Sketch)
    ├ Pad004 (Pad)
    │  └ Sketch006 (Sketch)
    ├ Pocket001 (Pocket)
    │  └ Sketch007 (Sketch)               <- picture
    ├ PolarPattern003 (PolarPattern)
    └ Pocket002 (Pocket)
       └ Sketch008 (Sketch)
Attachments
Fan cooling duct _SHALM.FCStd
(182.11 KiB) Downloaded 18 times
Capture du 2021-10-26 19-14-41.png
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papyblaise
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Re: Misalignment on polar pattern?

Post by papyblaise »

I agree Schlm , and Refine = True to finish as a one part
more advise : the best is constraint all sketches
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fan cooling.PNG
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domad
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Re: Misalignment on polar pattern?

Post by domad »

naasking wrote: Tue Oct 26, 2021 12:35 pm .....
Hello naasking, greetings to the Community!
.... you must first make the "PolarPattern" of "Pad003", then the "Draft" (in this function the "Neutral plane" must be indicated) and finally the "PolarPattern" of the "Draft".
I attach two files one is the adjustment of yours, the other a little neater in the modeling flow.
Attachments
Fan cooling duct v2-1.FCStd
(176.84 KiB) Downloaded 19 times
Fan cooling duct v2-fixed_up.FCStd
(167.58 KiB) Downloaded 20 times
comparison.png
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Ordered.png
Ordered.png (196.53 KiB) Viewed 854 times
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Shalmeneser
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Re: Misalignment on polar pattern?

Post by Shalmeneser »

domad wrote: Tue Oct 26, 2021 7:26 pm .... you must first make the "PolarPattern" of "Pad003", then the "Draft" (in this function the "Neutral plane" must be indicated) and finally the "PolarPattern" of the "Draft".
Why don't you use the same PolarPattern for Pad003 AND Draft ?
naasking
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Re: Misalignment on polar pattern?

Post by naasking »

I think I understand, the order in which I include features in the pattern matters.

I agree on constraining all of the sketches. I had started with another parametric design with fully constrained sketches and spreadsheet variables, but the approach started getting way too complicated and caused all kinds of issues. I started playing with this approach and it was coming along much better until I hit this little snag. Shalmeneser's second design looks simpler still. Thanks for all of the suggestions!
chrisb
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Re: Misalignment on polar pattern?

Post by chrisb »

domad wrote: Tue Oct 26, 2021 7:26 pm the other a little neater in the modeling flow.
Is there a certain reason why you left most sketches unattached?
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domad
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Re: Misalignment on polar pattern?

Post by domad »

Greetings to the Community!

- @Shalmeneser I didn't use them together as they can give rise to unexpected results, generally I tend to simplify the functions (patterns, fillets, bevels, etc.) that is, not to group them together, giving the function code the minimum possible data to be processed.

- No @chrisb I don't have a specific reason, but since I align sketches through the use of transformation tools and "Draft" snaps in wireframe mode (99% model in this mode) I simply don't have this need often (but the ability to bind the sketch to a face/surface is very, very important).
The point [0,0] (intersection of the Cartesian axes of the sketcher, "strategic" for my way of modeling) I always use it as a reference or origin point of the sketch / body, it almost always does (99.99%) part of the sketch itself (I never place it outside).
I always mean the body generated by "Part Design" (and everything that is used to generate it) as unique/monolithic and therefore the point of origin [0,0] or simply, for me, "pivot" I never place it at outside the belonging sketch, this allows me to position/align the sketch easily in the point of interest.
Translation permitting, I hope I have been sufficiently understandable.
A greeting :)
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