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          Blender Tutorials: 608 Bearing - part 3

Part 3 Adding the Ball Bearings

Video Tutorial of this pages contents

In Parts 1 and  2 we created the bearings inner and outer race, now we  need to add some ball bearings. The 608 bearing has 7 balls so we will create and position one ball and then use a similar spin process to position the other six. This time though we will use "Spin Dup" to duplicate the selected vertices of the first ball around the cursor at the required step positions.

In front view Num-Pad 1, go into edit mode Tab, select wire frame Z, and de-select all vertices A.

Before we insert a Sphere to use as the ball bearing we need to position the cursor central to the bearing groves of the inner and outer race. To do this we will hide all the vertices of the bearing race other than the perpendicular section directly above the cursor.
Bearing Race

Press B (Box Select) and drag a selection box to select all the vertices to the right of the vertical centre line. Press B again and select all the vertices to the left of the centre line. Repeat this again to select the remaining vertices below the horizontal centre line. If you select the wrong vertices simply press Ctrl-Z to undo the selection.

You should be left with only the vertices directly above the bearing centre deselected.

Press the H key to hide the selected vertices. The vertices haven't been deleted they are hidden so they don't clutter the view and cant be edited. You can retrieve these vertices at any time by pressing Alt-H.
Select Vertices

You will now have one row of vertices directly above the bearing centre.

Selected Vertices hidden

Press NumPad 3 to go into side view and select RMB the centre vertex of the inner race bearing groove. Now add to the selection Shift-RMB the vertex directly above this on the outer race. The centre of these two vertices is the centre point for the ball bearing.

Press Shift-S to bring up the snap menu and select Cursor->Selection. The cursor will be positioned at the insertion point for the first ball.
Centre Cursor

Unhide the vertices we hid to make positioning the cursor easy by pressing Alt-H. Change to front view NumPad 1 and Tab into Object Mode. You will see the cursor positioned between the bearing races directly above the Object Centre.

UV Sphere 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. To achieve this it is necessary to insert the sphere whilst in the top view, so press Num-Pad 7 for the top view and then press the Space Bar to open the Toolbox. select:  Add > Mesh > UVsphere.
Unhide vertices

Insert UV Sphere
Accept the default 32 segments and 32 rings, a UV sphere will be inserted centred on the cursor with a diameter of 2mm. The mode will have switched to Edit Mode and all the vertices will be selected. If you click into front view Num-Pad 1. You will see the bearing is hanging in space and too small for the race. To correct this we need to scale the bearing.
Ball Bearing to small

To obtain the correct scale factor, divide the required size of the ball by the inserted size of the UV sphere. As the balls are 3.95mm diameter and the UV sphere is 2mm then: 3.95 / 2 = 1.975.

Press S for scale 1.975 for the amount and Enter to accept. The ball now correctly fits the race.

Blender 2.44 Update
Add UVsphere When you add a UV sphere there is a new floating panel that allows you to specify the radius, along with the segments and rings of the sphere. So you no longer need to calculate the scale factor when imputing some of the mesh primitives.
You can now simply hold down Shift and Click LMB over the radius figure and input the new radius of 1.975 and click OK. The UVsphere will now be inserted at the correct size.

Its still good to understand how to calculate a scale factor, as it will be needed in many other modelling situations.
Scale UV Sphere

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 select RMB the bearing race. Press Shift-S to bring up the snap menu and select cursor->Selection. The cursor will be repositioned to the centre of the bearing. Now reselect RMB the Ball

Centre Cursor In the Mesh Panel there are three options for moving the cursor.

Centre: moves the object so it is centered over the Object Centre.

Centre New: Moves the Object Centre to the centre of the object

Centre Cursor: moves the Object Centre to the cursor position, which is the option we require.
Centre Cursor

With one ball in place we now need to create the other six. As the cursor is on the bearing center we can duplicate the  first bearing 7 times around the race.

To achieve this Tab into Edit Mode.

In the Mesh Tools panel set the Deg: and Steps: as shown.

     Spin Dup

Press Spin Dup to duplicate the vertices seven times around the cursor. As with the spin command we have just placed a copy of the original ball over the top of the first one. To correct this select all vertices A. You will need to press it twice, once to de-select the last ball and then to select all. Press W (Specials Menu) and then select remove doubles.
Spin Dupe

To change the appearance from the faceted surface of the UVsphere to a smooth surface, with all vertices selected click "Set Smooth" in the Links and Materials panel.

The balls are now created and positioned around the bearing. Press Tab to go into Object Mode, Z for solid view and rotate the view with the MMB to see the bearing as a 3D object.

In the Links and Materials panel rename OB:Sphere to OB:608-Balls

If you haven't already done so press Ctrl-W and save your work.

Ball Bearings Located

Part 4 modeling 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.   

The following is a video tutorial of the above information

<< 608 Part 2 Ball Bearings Tutorials 608 Part 4 The Cage >>

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