Adding the Ball Bearings
At the end of the spin process the vertices of the last created instance remain selected, which is useful as they lie parallel to the side view and we need to use them to position the 3D Cursor for the first ball bearing placement. If you press Z to open the Shading menu and choose Wireframe, it will be easier to see the selected vertices.
Firstly though we need to hide all the vertices that are currently not selected. Press Shift-H and they will be removed from view.
On the number pad press Num3 to go into side view.
LMB select the the vertex that lies on the top of the curved bearing groove of the outer race (on the blue Global Z-axis line). All other vertices will become deselected. Then Shift-LMB select the bottom vertex on the curved bearing groove of the inner race.
We can now use Blenders snap function to position the 3D Cursor central to the two selected vertices, which will be the centre point of the ball bearing.
Press Shift-S to open the snap menu and choose Cursor to Selected. The 3D will jump to the centre point of the first ball bearing.
We can now unhide all the vertices we had previously hidden by pressing Alt-H and then deselect all the vertices using Alt-A
Tab into Object Mode and press Num1 to go into Front View.
To form the ball we will use one of Blenders preset objects, the UV Sphere. The sphere is constructed from a series of latitudinal and longitudinal edges with poles at the top and bottom. We will be using the geometry from the sphere to construct the bearing cage and it is important that it is oriented correctly.
When we insert the sphere we need one of the poles to be pointing towards the bearing centre. By default the UVSphere is inserted with its poles on the Z axis.
Press the Shift-A to open the Add Menu and select: Mesh > UVsphere. A UV sphere will be inserted centred on the cursor with.
In the Add UV Sphere panel change Segments to 32, Rings to 32 and radius to 1.975 (the radius of the ball bearing)
The Object Centre for the ball is currently central to the UV Sphere and it would be much more useful if it was positioned central to the Bearing. To achieve this Tab into Object mode and LMB select the bearing race. Press Shift-S to bring up the snap menu and select cursor to Selection. The cursor will be repositioned to the centre of the bearing. Now LMB reselect the Ball.
From the Object menu of the Header Bar select Set origin >> Origin to 3D Cursor and the UV Spheres origin will be moved to the centre of the bearing.
With one ball in place we now need to create the other six. As the cursor is on the bearing centre we can duplicate the first bearing 7 times around the race.
To achieve this Tab into Edit Mode.
On the Tool Shelf click the Spin icon.
LMB click on the blue spin widget then in the Spin Panel set Steps to 7, Angle to 360, Axiz-Y to 1, Axis-Z to 0, and select Dupli.
With the Spin Dupli process we have just placed a copy of the original ball over the top of the first one. To correct this select all vertices A then Press RMB to select the Context Sensitive menu and select Remove Double Vertices.
The balls are now created and positioned around the bearing. Press Tab to go into Object Mode, Z to open the Shading Menu and choose Solid. Rotate the view with the MMB to see the bearing as a 3D object.
To change the appearance from the currently faceted surface to a smooth surface, with the UV Sphere selected, from the Header menu choose Object >> Shade Smooth.
As the Balls will be used as the basis of the cage, which has a number of sharp edges these can be protected from the smooth shading by clicking Auto Smooth located on the Normals tab of the Object Data panel within the Properties window
In the Object Data panel of the Properties window rename "Sphere" to "608-Balls"
If you haven't already done so press Ctrl-S and save your work.
Part 4 modelling the cage becomes a little more tricky but as you get used to panning, rotating and zooming the view, selection of vertices and constructing models becomes a little easier to achieve.
3D Computer Graphics Using Blender 2.8 - Modelling Methods, Principles & Practice
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