Sub-shape binder sketch error

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salp
Posts: 250
Joined: Thu Nov 21, 2013 11:58 pm
Location: Putnam, NY

Sub-shape binder sketch error

Post by salp »

I am trying to create a more accurate angle grinder model, and I'm not understanding how to use Shape-Binder.

OS: Ubuntu 22.10 (ubuntu:GNOME/ubuntu)
Word size of FreeCAD: 64-bit
Version: 0.20.2.29603 (Git) AppImage
Build type: Release
Branch: (HEAD detached at 0.20.2)
Hash: 930dd9a76203a3260b1e6256c70c1c3cad8c5cb8
Python 3.10.8, Qt 5.15.4, Coin 4.0.0, Vtk 9.1.0, OCC 7.6.3
Locale: English/United States (en_US)
Installed mods:
* POV-Ray-Rendering
* Render 2023.2.3
* FC_Libre
* Assembly4 0.50.1
* DynamicData 2.46.0
* BIM 2021.12.0
* Curves 0.6.8
* IconThemes
* fasteners 0.4.56
The original attempt generated a 6MB+ file, so I'm attaching a screenshot.
Selection_006.png
Selection_006.png (122.34 KiB) Viewed 1137 times


I am trying to create a more realistic model and was thinking the correct work flow is to create a few sketches and then use these sketches as reference, the reference sketches are called "Vertical" and "Horizontal".

I am using the Part-Design workbench, and to organize I'm putting everything inside a Part container (see attached).
Selection_007.png
Selection_007.png (36.19 KiB) Viewed 1137 times

My work flow is as follows:
  • I create a Part
    Add Body and rename it "Reference"
    Create 2 sketches and rename then to Vertical and Horizontal
    Create a new body for the head of the grinder
    Use Shape Binder link to Vertical sketch and select all the items in the sketch
    Highlight the binder and create sketch
    Use external reference tool and select the arcs and circles
* As I start to draw the arcs and constrain the end points to the external refrence I get "Partial Redindant" error and the end point DO NOT join.

I have not used Binder's before and I'm assuming that I'm doing it wrong.

Looking for advice on how to approach this project so it works and learn a robust way of creating the drawings.

This is my broken file.
Attachments
Angle_Grinder_v2.FCStd
(22.91 KiB) Downloaded 12 times
chrisb
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Joined: Tue Mar 17, 2015 9:14 am

Re: Sub-shape binder sketch error

Post by chrisb »

An arc has 5 degrees of freedom (DOF). If you apply 3 coincidences, they consume 6 DOF, thus one is redundant.
You can eg use a point-to-point tangency (3 DOF) plus a coincidence (2 DOF) on the endpoints.
A Sketcher Lecture with in-depth information is available in English, auf Deutsch, en français, en español.
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Shalmeneser
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Joined: Wed Dec 23, 2020 12:04 am
Location: Fr

Re: Sub-shape binder sketch error

Post by Shalmeneser »

Arcs and Sketcher_External is not always an easy job.

* center on center : 2 DOF Sketcher_ConstrainCoincident
* (left) point on point : 2 DOF Sketcher_ConstrainCoincident
* (right) point on line : 1DOF Sketcher_ConstrainPointOnObject
2+2+1 = 5

Sketcher_CreateArc :
1) click on center
2) click on left point
3) click on right line/arc !!! (you must not click on the right point)
easier to do than to explain.
Attachments
Capture d’écran 2023-06-04 125058.jpg
Capture d’écran 2023-06-04 125058.jpg (10.36 KiB) Viewed 997 times
User avatar
salp
Posts: 250
Joined: Thu Nov 21, 2013 11:58 pm
Location: Putnam, NY

Re: Sub-shape binder sketch error

Post by salp »

"chrisb", "Shalmeneser"

Thank you both for the answer, because I was attaching to the external reference it did not occur to me that the DOF still apply.

Thank you
Sal
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