Array on curved surface (hexagon tool holder)

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M4x
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Array on curved surface (hexagon tool holder)

Post by M4x »

Hey everybody,

I'd like to get some modeling advice. I'm working on a part which I'm going to 3D-print. It's going to be a device where hexagon shaped tools can be inserted at different angles. This is how it looks like at the moment. The green body (Body_tool) represents the hexagon tool (just to make it clear what I'm trying to achieve).

overview
overview
Screenshot from 2023-05-27 13-20-24.png (28.03 KiB) Viewed 781 times

What I've done so far
  • Create a spreadsheet to hold the dimensions (dim)
  • Create the base body (half of it)
  • Create a pocket for the tool insert which points upwards
  • Make a polar pattern out of that pocket
  • Mirror the base body to get the second half of it
My tree view looks like this:

tree view
tree view
Screenshot from 2023-05-27 13-24-00.png (23.88 KiB) Viewed 781 times

Heads up: Currently, I'm using block constraints in the first sketch (used for the pad named Pad), since I'm not sure yet how I want the base body to be shaped in the end. Of course I'm going to replace those with proper dimensions.

Sketch with block constraints (used for Pad)
Sketch with block constraints (used for Pad)
Screenshot from 2023-05-27 13-22-37.png (19.75 KiB) Viewed 781 times

What's bothering me
1. Arrange hexagon pockets at curved shape
Basically, I'd like to create an "array" of hexagon shaped pockets side by side along a curved surface (marked in the following screenshot):

curved surface marked
curved surface marked
Screenshot from 2023-05-27 13-20-54.png (12.34 KiB) Viewed 781 times

It's working with a polar pattern like it's now. I had to play with the parameters. Is there an easier / more straight forward way?

2. Wall thickness
I've marked the minimum wall thickness I'd like to achieve in the end in the following screenshot:

minimum wall thickness
minimum wall thickness
Screenshot from 2023-05-27 13-22-01.png (13.84 KiB) Viewed 781 times

The elements created by the polar pattern are (of course) reducing this wall thickness. Like it is now, I could create a pad to make sure I'm getting my desired wall thickness. Again, I'm wondering - Is there an easier / more straight forward way?


Would it be useful to have a closer look at the array tools of the Draft_Workbench or Lattice2_Workbench?

Thank you very much! I'm looking forward to your ideas and approaches! :D
Max

FreeCAD version information

Code: Select all

OS: Ubuntu 22.04.2 LTS (ubuntu:GNOME/ubuntu)
Word size of FreeCAD: 64-bit
Version: 0.21.0.33303 (Git) AppImage
Build type: Release
Branch: master
Hash: 5b075a9938b78076fdde9034de4a05685e42690e
Python 3.10.11, Qt 5.15.8, Coin 4.0.0, Vtk 9.1.0, OCC 7.6.3
Locale: English/United States (en_US)
Installed mods: 
  * LCInterlocking
  * kicadStepUpMod 10.19.4
  * Lithophane
  * lattice2 1.0.0
  * Defeaturing 1.2.0
  * Manipulator
  * fasteners 0.4.56
  * Assembly3 0.12.0
  * sheetmetal 0.2.63
  * Assembly4
  * Curves 0.6.9
  * POV-Ray-Rendering
  * 3DfindIT 1.2.0
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M4x
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Re: Array on curved surface (hexagon tool holder)

Post by M4x »

And of course, the FreeCAD file attached to this post.

hexagon_tool_holder_forum.FCStd
(80.52 KiB) Downloaded 13 times
chrisb
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Re: Array on curved surface (hexagon tool holder)

Post by chrisb »

It's all a question of the center of curvature: Use e.g. a Datum Line as the rotation center of the PolarPattern and similar with Sketch001, which has to be moved in Z direction in addition.
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chrisb
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Re: Array on curved surface (hexagon tool holder)

Post by chrisb »

I was half wrong, when suggesting to attach the second sketch to the center of curvature. You have to attach it to the curve itself and then rotate it, move vertically - which is after the rotation the x-direction - and move it along the map path:
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chrisb
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Re: Array on curved surface (hexagon tool holder)

Post by chrisb »

I was half wrong, when suggesting to attach the second sketch to the center of curvature. You have to attach it to the curve itself and then rotate it, move vertically - which is after the rotation the x-direction - and move it along the map path:
Attachments
hexagon_tool_holder_cb.FCStd
(43.78 KiB) Downloaded 12 times
SnipScreenshot-1d4766.png
SnipScreenshot-1d4766.png (18.62 KiB) Viewed 554 times
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
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M4x
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Re: Array on curved surface (hexagon tool holder)

Post by M4x »

Wow, I love this forum! That looks very promising, thanks chrisb! :P

I've tried to reproduce your approach by deleting the support for Sketch001 and attaching it to Sketch.Edge3 using the Map Mode FrenetNB. As soon as I've done this Sketch001 gets positioned beside Sketch. By looking at your example file, I don't get it why it's different there. You're positioning Sketch001 after attaching it to Sketch.Edge3 but I can't find a clue regarding any movement on the x axis (origin). :oops:

Position of Sketch001 after attaching it to Sketch.Edge3
Position of Sketch001 after attaching it to Sketch.Edge3
Screenshot from 2023-05-28 22-00-59.png (51.69 KiB) Viewed 363 times
Attachments
hexagon_tool_holder_forum_3.FCStd
(55.04 KiB) Downloaded 6 times
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M4x
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Re: Array on curved surface (hexagon tool holder)

Post by M4x »

Never mind, it's the changed position of the sketch itself. You placed it in the center and didn't.

Screenshot from 2023-05-28 23-13-54.png
Screenshot from 2023-05-28 23-13-54.png (23.35 KiB) Viewed 338 times
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