Scripted Parts: Ball Bearing - Part 2

From FreeCAD Documentation
Revision as of 09:53, 17 August 2016 by R-Frank (talk | contribs)
Tutorial
Topic
Part Scripting - Ball Bearing #2
Level
Beginner
Time to complete
30 min
Authors
r-frank
FreeCAD version
0.16.6706
Example files
See also
None


Introduction

This tutorial is meant as a beginner's introduction to creating parts with python scripts within FreeCAD.
This tutorial will cover how to build a ball bearing with a workflow that consists of creating sketches and revolving them.
The code will produce a new FreeCAD document with 12 shapes (Inner Ring, Outer Ring and 10 balls/spheres).
It will look like this:


Workflow

The workflow is more or less identical how you would create the part in part design workbench.
Just some small differences.

  • Create a new empty document and make it the active document
  • Draw the basic shape of the outer ring consisting of four straight lines and four arcs
  • Connect the lines and arcs and upgrade them to one single wire
  • Upgrade the wire to a face
  • Revolve the face to get a shape
  • Draw a circle
  • Upgrade circle to wire
  • Upgrade wire to face
  • Revolve face and apply boolean cut to obtain groove in outer ring
  • Draw the basic shape of the inner ring consisting of four straight lines and four arcs
  • Connect the lines and arcs and upgrade them to one single wire
  • Upgrade the wire to a face
  • Revolve the face to get a shape
  • Draw a circle
  • Upgrade circle to wire
  • Upgrade wire to face
  • Revolve face and apply boolean cut to obtain groove in inner ring
  • Insert balls with same workflow as in part 1 (because of effectiveness)
  • Set view to axometric
  • Zoom to fit all

Making the groove

Bla and blub ...

Inserting the balls

Notes

Bla and blub ...


Links

Scripted objects: The wiki page explaing the basics of scripting
Topological data scripting: A tutorial for covering basics of scripting
Scripted Parts: Ball Bearing - Part 1: Doing it with part primitives
Bearings from scripted sketches: Base for this tutorial, thanks to JMG ...


Code

## Ball-bearing script
## 11.08.2016 by r-frank (BPLRFE/LearnFreeCAD on Youtube)
## based on ball bearing script by JMG
## (http://linuxforanengineer.blogspot.de/2013/12/bearings-from-scripted-sketches.html)

#needed for doing boolean operations
import Part
#needed for calculating the positions of the balls
import math
#needed for translation and rotation of objects
from FreeCAD import Base

#VALUES#
#(radius of shaft/inner radius of inner ring)
R1=15.0
#(outer radius of inner ring)
R2=25.0
#(inner radius of outer ring)
R3=30.0
#(outer radius of outer ring)
R4=40.0
#(thickness of bearing)
TH=15.0
#(number of balls)
NBall=10
#(radius of ball)
RBall=5.0
#(rounding radius for fillets)
RR=1
#first coordinate of center of ball
CBall=((R3-R2)/2)+R2
#second coordinate of center of ball
PBall=TH/2

#Create new document
App.newDocument("Unnamed")
App.setActiveDocument("Unnamed")
App.ActiveDocument=App.getDocument("Unnamed")
Gui.ActiveDocument=Gui.getDocument("Unnamed")

#Lines for basic shape of outer ring
L1o=Part.makeLine((R4,0,RR),(R4,0,TH-RR)
L2o=Part.makeLine((R4-RR,0,TH),(R3+RR,0,TH)
L3o=Part.makeLine((R3,0,TH-RR),(R3,0,RR))
L4o=Part.makeLine((R3+RR,0,0),(R4-RR),0,0)
#Corner rounding for basic shape of outer ring
A1o=Part.makeCircle(RR,Base.Vector(R4-RR,0,TH-RR),Base.Vector(0,1,0),0,90)
A2o=Part.makeCircle(RR,Base.Vector(R3+RR,0,TH-RR),Base.Vector(0,1,0),90,180)
A3o=Part.makeCircle(RR,Base.Vector(R3+RR,0,RR),Base.Vector(0,1,0),180,270)
A4o=Part.makeCircle(RR,Base.Vector(R4-RR,0,RR),Base.Vector(0,1,0),270,360)
#Connect Lines and arcs to make wire and upgrade to face
OR=Part.Wire([L1o,A1o,L2o,A2o,L3o,A3o,L4o,A4o])
OR=Part.Face(Or)
OR=OR.revolve(Base.Vector(0,0,1),Base.Vector(360,0,0))

#Todo


#Make it pretty#
App.activeDocument().recompute()
Gui.activeDocument().activeView().viewAxometric()
Gui.SendMsgToActiveView("ViewFit")