Requesting Guidance on Crescentic Construction

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jumblies
Posts: 6
Joined: Thu Dec 24, 2020 3:20 pm

Requesting Guidance on Crescentic Construction

Post by jumblies »

Hello Again,

I hope someone can help point me in the right direction.

I have a crescent shaped object and it needs an elongated keyhole in it. Here is an image of the object I'm modeling.

https://cfcdn.zulily.com/images/cache/p ... 382144.jpg

I managed this with Curves WB -> Sketch on curved surface. Then I increased the offset and thickness and did a boolean cut to do the basic shape.

Questions:
Is this the best way to have achieved this shape on a curved surface?

How do I modify the keyhole shape? I need to have the keyhole tapered on the concave side of the crescent but I need guidance on how to widen the concave edges of the slot. The cut opening in the object is the correct convex side sizing.



OS: Windows 10 Version 2009
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.19.24276 (Git)
Build type: Release
Branch: releases/FreeCAD-0-19
Hash: a88db11e0a908f6e38f92bfc5187b13ebe470438
Python version: 3.8.6+
Qt version: 5.15.1
Coin version: 4.0.1
OCC version: 7.5.0
Locale: English/United States (en_US)
Attachments
zu71047443_alt_1_tm1552382144.jpg
zu71047443_alt_1_tm1552382144.jpg (19.89 KiB) Viewed 830 times
Handle.FCStd
(86.44 KiB) Downloaded 15 times
chrisb
Veteran
Posts: 53930
Joined: Tue Mar 17, 2015 9:14 am

Re: Requesting Guidance on Crescentic Construction

Post by chrisb »

If the keyhole is tapered, you can try a loft.

Besides: You must not use a PartDesign feature in a Part operation, use the whole body instead.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
jumblies
Posts: 6
Joined: Thu Dec 24, 2020 3:20 pm

Re: Requesting Guidance on Crescentic Construction

Post by jumblies »

@chrisb Thanks for the reply. I appreciate your advice on not mixing Part and PartDesign. I have done the boolean in Part.

I might be able to achieve the goal with a big chamfer or fillet.

Do you mean loft a sketch on surface?

I tried to use part design boolean different ways and end up a whole bunch of duplicate child item errors.

Code: Select all

18:10:45  299.22 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Pad
18:10:45  299.22 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Sketch_On_Surface
18:10:45  299.22 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Sketch_On_Surface
18:10:45  299.22 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Pad
18:12:34  409.084 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Pad
18:12:34  409.084 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Sketch_On_Surface
18:12:34  409.084 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Pad
18:12:34  409.084 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Sketch_On_Surface
18:12:34  409.084 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Sketch_On_Surface
18:12:34  409.084 Tree.cpp(302): [ComboView] duplicate child item Handle#Boolean.Pad
Is there a better way to attach the keyhole sketch to the curved surface than Sketch_On_Surface?
chrisb
Veteran
Posts: 53930
Joined: Tue Mar 17, 2015 9:14 am

Re: Requesting Guidance on Crescentic Construction

Post by chrisb »

I had thought about something like that:
SnipScreenshot-54bfed.png
SnipScreenshot-54bfed.png (23.75 KiB) Viewed 719 times
Attachments
Handle_cb.FCStd
(115.63 KiB) Downloaded 18 times
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
jumblies
Posts: 6
Joined: Thu Dec 24, 2020 3:20 pm

Re: Requesting Guidance on Crescentic Construction

Post by jumblies »

Wow! Thanks for your guidance. I think I'll try it tonight with your suggestion and loft so I can learn that technique. I think lofting through a few profiles would give me exactly what I'm seeking with complex transitions inside the handle.

Even your comment about not mixing Part and PartDesign helped me make some strides last night and I'm really close if not at my goal design.

Thank you again sir!
Attachments
Handlejpg.jpeg
Handlejpg.jpeg (40.11 KiB) Viewed 661 times
chrisb
Veteran
Posts: 53930
Joined: Tue Mar 17, 2015 9:14 am

Re: Requesting Guidance on Crescentic Construction

Post by chrisb »

You're welcome. You have probably noted that the axes of the cylindric parts are different from the MapSketchToSurface version.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
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