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          Blender Tutorials: 608 Bearing - part 2






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Part 2 Detailing the Cross Section








With the corner fillets in place it's now time to define the inner and outer race.

The thickness of each race is 1.92mm, so we need to divide the cross section accordingly.

(You should now know the keyboard commands to select, extrude and constrain vertices to a set axis, so from now on I will only include the commands for these operations occasionally.)

Select the bottom left vertex and Extrude  it 1.92mm in the Z axis. Then Extrude this vertex 7mm in the Y axis.

Select the top left vertex and extrude it -1.92mm in the Z axis. Then extrude this 7mm in the Y axis.

The thickness of the Inner and outer race is now defined.
Defining the Inner and Outer Race





The next stage is to form the groove's that the ball bearings will run in. To do this we must spin a circle from the centre point of the two bearing races.

Hold Shift and Select RMB the four vertices that are on the ends of the two edges that we have just created to define the thickness of the inner and outer race.

Press Shift-S and snap the cursor to the selection. Because we have selected more than one vertex the cursor will snap to the centre of all the vertices.
Centre of Bearing





ensure nothing is selected A and holding the Ctrl key click LMB any where near the cursor. A new vertex will be created.

Snap the vertex to the cursor. Shift-SSelection to Cursor.

The Ball Bearings have a  diameter of 3.95mm so we need to spin a radius of 1.975mm.

Extrude the vertex -1,975 on the Y axis.
Add Vertices





On the Tool Shelf click Spin.

On the Spin Options panel that opens at the bottom of the Tool Shelf, set Angle: to 360 as we are going to spin a complete circle. Set  Steps: to 64. This will give us a sufficiently detailed circle.


Its worth noting that if possible you should always choose a number of steps that will give a vertex on each of the circles quadrants.

Spin Radius





Excluding the vertices whose edges intersect the line defining the inner and outer race, the centre vertices are no longer required and can be deleted.

Rather than Shift-RMB selecting all the vertices Blender allows you to box select a group of vertices. To do this press the B key, the mouse pointer will change to a cross hair. Position it above and to the left of the vertices you need to delete. Press and hold the LMB and drag the cross hair to the lower right of the vertices to be deleted. release the LMB. The vertices within the selection box will now be selected.

Press X and Delete the vertices.

Until now we have been working with the pivot set to Median. This means that if you rotate or scale a group of vertices the centre of the rotation or scale will be the centre of the selected vertices.

To align the end vertices of the bearing grooves we need to rotate individual vertices around the centre of the ball bearing. 
Select to delete





Pivot around cursor
On the view header click on the pivot button and choose 3D Cursor. As the cursor is already positioned on the centre of the ball bearing we can rotate the end vertices from this point.

Note the Z location of the top horizontal edge, marked A in the image above. The location is displayed in the Transform Panel of the Properties Shelf when the edge is selected.

Zoom in on one of the end vertices by rotating the SW (scroll wheel) and panning  by pressing Shift and holding the MMB whilst moving the mouse. To rotate the vertex press R and drag the vertex until it's Z location is the same as the horizontal edge defining the inner portion of the bearing race. Click the LMB to accept the rotation. Repeat this on all four vertices
Z Location





Align Cursor
Scale to Line





Delete Reference Edges
We now have enough detail to complete the inner race. Select the 6 reference vertices shown above and X delete them
Bottom Race
We are left with the two corner fillets and the bearing groove.





Construct Edge
To reconstruct the face of the bearings inside diameter select the inner most vertices on the bottom fillets and press F to insert an edge.
Inner Race

Extrude the end vertex of the bearing groove and constrain to the Y axis






Position Cursor

To align this to the outer edge of the bearing snap the cursor to the top vertex of the fillet. Re-select the extruded vertex and scale S constrain to the Y axis and 0 to set its position in line with the cursor. 
Chamfer

The inner edge of the inner race has a 0.05mm chamfer. to form this press G to grab the vertex (move), Y to constrain, 0.05 to set its position.
Now extrude this vertex -0.05 in the Y axis then grab G, constrain Z, -0.05 to position. The chamfer is now formed.





Finally join the chamfer to the fillet with an edge. Select the end vertices on the chamfer and fillet and F to insert a new edge.

Repeat this on the other end to complete the section of the inner race.

Insert Edge





The outer race is a little mode difficult as it contains a circlip groove and location for the dust shield.

The creation of this form is fairly straight forward. From the top left corner vertex simply extrude and constrain the movement to the Z and Y axis at the dimensions opposite.

Once completed repeat this on the other end of the bearing.

Once the edges are in place you can refine the cross section by adding a 0.02mm chamfer on each of the corners. This can be achieved by deleting one edge, extruding the end vertices 0.02 in the direction of the deleted edge, reinserting the edge and then moving the corner vertices 0.02 in the perpendicular axis.






Select Vertices to delete

Delete X the six vertices used as reference points
Construction Lines removed
The basic shape of the outer race is now constructed. Select the vertices either end of a gap and press F to insert an edge. Do this one edge at a time until the outer race is complete.





Complete Outer Race
The section through the bearing is now complete and we are ready to spin this through 360 degrees to form the 3D model. However the spin process rotates around the cursor and it is in the wrong position. When we started to construct the section we worked from the Object Centre which defined the centre axis of the bearing.

To snap the cursor to the object centre press Tab to go into Object Mode. From here you can press Shift-S Cursor to Selection The selection point of an object is the object centre.
Cursor to Object Centre





Edit Mode Front View

Tab back into Edit Mode and press A to select all vertices.

As we want to spin the bearing in the front view press NumPad 1 and the view will change with the vertices lined up above the cursor.






Spin
On the Tool Shelf Press Spin, In the Spin Options panel that opens at the bottom of the tool sheld  panel check Angle: is set to 360 and Steps: is set to 64. The bearings inner and outer race will be formed.

The last set of vertices created will now be selected but they aren't yet connected to the first set of vertices.

Remove Doubles

To join these press A twice to select all the vertices then W to bring up the Specials menu, from this select Remove Doubles, which will merge any vertices that are sitting on top of each other.






That's it for modelling the inner and outer race. Press Tab to go into Object Mode and rotate the view with the MMB to see the 3D view of the bearing from any angle. You can pan the view with Shift-MMB and moving the mouse.
If you lose your model from the view you can retrieve it by pressing the Home key


You will notice however that all the faces are flat with faceted edges to correct this in the view we will smooth the surfaces we need to appear round and retain edges we need them to be sharp.

Tab back into edit mode and select all A. On the Tool Shelf press the Shading: "Smooth" button.

If areas of black appear on the surface of the bearing press Ctrl-N and this will Recalculate the Normals to the Outside.
Note: if you ever need your normals to point towards the inside of a model you press Ctrl-N and then check the Inside option on the Make Normals Consistent options that appear at the bottom of the Tools Shelf.
3D View





On the Object Modifiers panel press Add Modifier and from the pop up menu choose Edge Split.
Add Modifier





Edge Split Modifier





In the Edge Split modifier  " Sharp Edges" and "Edge Angle" will already be selected.  Leave Split Angle:30. Which will smooth the join between any faces with an angle of 30 degrees or less. You may notice though that there may not be a sharp edge between the bearing groove and the inner edges of the race because the angle is less than 30 degrees. This can be corrected by marking these edges for the Edge Split modifier to recognise as sharp. Edge Split





Mark Sharp
With the four loops selected press Ctrl-E to bring up the Edge Specials menu.

Select "Mark Sharp". This will tell the Edge Split modifier that these edges should be viewed as a sharp edge and it won't apply any smoothing to them.
Select the edge loops on the outer edges of the bearing groove. This can be achieved by first deselecting all vertices A and then selecting each loop Shift-Alt-RMB
Mark Sharp





Before we create the next object we will give this one a meaningful name. In the Object Data Panel Click in the OB: Plane field
Links & Materials

Delete plane and re name the object 608-Race


This is a good point to save your work. Press Ctrl - W and accept the save menu.


In Part 3 we will be placing the Ball Bearings within the Inner and Outer Race
Completed Bearing Race



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