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Back to Tutorials |
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Part 2 Guide Roller - Axle
We have
now got the V-Roller with two bearings inside it, so the next thing is
to design the axle. I intend to make aluminium castings to hold four
rollers and the lead screw nut and at this stage a casting thickness of
10mm seems appropriate. One end of the axle needs to fit into the
casting the other end needs to hold the bearings. These are the
governing factors for the length and profile of the axle. |
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If it is not still open
from part one, open V-Roller.blend.
In
the outliner make sure the eye icon is open for the two bearings and
closed for the V-Roller and Cylinder.
We
only need the bearings in view to position the Object Centre for the
axle and the section of the axle profile that the bearings sit on. |
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RMB Select the right
hand bearing and Tab
into Edit Mode. Alt-RMB
select a loop of vertices on the outer right hand edge of the
bearing and snap the cursor to the centre of this loop of vertices Shift-S
Cursor>Selection. Tab
back into Object Mode.
Go into side view NumPad
3.
Press the Space Bar
and from the Toolbox menu select Add>Mesh>Plane. In the
Link and Materials panel change the name to OB:V-RollerAxle. |
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Shift-RMB the top
right hand vertex to deselect it, then press X to delete the
remaining three vertices.
RMB
the remaining vertex to select it, then Tab into Object
Mode. (The vertex will
be easier to locate when we Tab back into Edit Mode for the
V-RollerAxle).
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Select the right hand bearing and Tab
into Edit Mode for this object. Select the top right hand vertex of the
bearing bore (the
vertex on the bearing bore not one of the fillet vertices, check you
have the correct vertex in front view NumPad 1), snap the cursor
to this vertex Shift-S
Cursor>Selection. Tab
back into Object Mode. |
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In the Outliner select
V-RollerAxle and Tab
into Edit Mode. The single vertex is selected so snap it to the cursor Shift-S
Selection>Cursor. Tab
back into Object Mode.
Select
the Right Hand Bearing and Tab
into Edit Mode. Select any vertex on the outer right hand edge and snap
the cursor to it. Tab
back into Object Mode.
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the Outliner select V-RollerAxle and Tab into Edit Mode. |
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Make sure the pivot point
is set to 3D cursor.
With the single vertex
still selected Scale
the vertex along the Y-axis
to the cursor position 0. |
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The vertex
is now positioned aligned to the bearing bore and right hand edge. In
side view NumPad 3
Extrude the vertex along the Y
axis -17.5mm. RMB
select the right hand vertex and Extrude
it along the Z-axis
2mm.
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the outliner close the eye icon for the two bearings to remove them
from view. You
are left with two edges that when spun around the Object Centre will
form the bearing location area of the axle. |
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From
the two edges that were positioned on the bearing bore extrude the
following profile constraining the extrusions to the Y or Z-axis and
dimensions indicated. The end chamfers are created by extruding 0.6mm
in the Y-axis then grabbing and moving the vertex -0.6mm in the Z-axis.
When complete this will form the basic profile of the axle. | |
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A little more refinement
is required before we spin the axle around the Object Centre. Fillet
radius and chamfers need to be added.
First we will add a fillet radius of 0.3mm to the inside angle of the
central up-stand.
Select the inner corner vertex indicated and Extrude this
in the Z-axis
0.3mm
to point A (vertex to
spin), then extrude this vertex |
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the cursor to the vertex on the centre point. |
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In the Mesh Tools panel
set Degr:90 and Steps:5, then press Spin. The corner fillet will be
formed.
Select the corner vertex and the fillet centre vertex (B) and delete
them.
Before connecting the fillet to the rest of the axle we can add a
chamfer to the top edge. |
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Select
the vertex on the top edge above the fillet and move it G
along the Y-axis
0.2mm.
Now Extrude
this vertex Y
-0.2,
then Grab
this and move
it Z -0.2.
A 45-degree chamfer has been added to the edge.
Select the end vertex of the chamfer and end vertex of the fillet and
connect them F.
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Reconnect the other end of the fillet to the end of the bearing
location.
Add a similar fillet and chamfer to the other side of the central
up-stand. |
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Tab into Object Mode
and snap the cursor to the Object Centre.
Tab back into Edit
mode.
Go
into front view NumPad 1
and select All vertices.
In
the Mesh Tools panel set Degr:360 and Steps:32, then press Spin. The
axle will be formed.
When fitting the axle into the casting we need to be able to stop it
rotating whilst tightening the retaining nut. The next step will be to
add some spanner flats to the central flange. |
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Shift-Alt-RMB select the loop of vertices around the opening of the spanner flat.
Add faces to the opening Shift-F, then beautify the fill Alt-F and then convert the created triangles to quads Alt-J.
Repeat this on the other spanner flat. |
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To
complete the axle select All
vertices, Remove doubles W
and Set Smooth W.
You may also need to recalculate the normals to the outside Ctrl-N.
To create a smooth surface with sharp edges, add an Edge Split modifier
with the default settings.
Press Ctrl-W
and save your work.
At this stage I have deliberately left the axle with plane ends rather
than generating a threaded profile. In large assemblies the
axle
will use substantially less computer overheads than one with a detailed
thread
profile.
In
part 3, I will detail how to set up and use the screw function to
create
a detailed thread suitable for producing a realistic render. |
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Continuing
with the V-Roller assembly, in the Outliner open the eye icon for the
two bearings and V-Roller. The assembly is starting to take shape but
still missing a retaining nut and washer.
The
nut
should also impart a small amount of pre-load onto the bearing to
remove any side piay. In true skateboard fashion I am going to use a
6mm nyloc-locking nut and washer.
To locate the washer and nut we only need the bearings in view, so in
the Outliner close the eye icon for the V-Roller and V-RollerAxle to
remove them from view. |
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Select the left hand
bearing and Tab
into Edit Mode. Alt-RMB
select a ring of vertices on the far left side of the bearing and snap
the cursor to the centre of them. Tab back into Object Mode.
Press the Spacebar
to open the
Toolbox and select Add>Mesh>Circle. From the popup menu
leave
vertices at 32, but change Radius to 3.2 then press OK to accept. This
will form the 6.4mm inside diameter of the washer.
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(Only
Edges) this vertex ring then press Esc to leave it in
place. We will scale the extruded vertices to form the outside diameter. |
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The Outside diameter of
the washer is 12.5mm so to find the required scale factor:
12.5 /
6.4 = 1.9531
With the extruded vertices still selected Scale 1.9531 to form the
outside diameter.
The thickness of the washer is 1.6mm so select All and Extrude (Region) Y -1.6
The basic profile of the washer is
formed, we now just need to add a chamfer on the corners.
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Go into edge select mode
and Shift-Alt-RMB
select the two outer and two inner edges. |
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Using the Bevel Centre
script and following the details given in 608 Part-4 add a
0.1mm chamfer. Back in vertex select mode select All and Set Smooth W, in the Modifiers
tab add an Edge Split modifier with the default settings. If Black
areas are present on the surface of the washer press Ctrl-N to
recalculate the normals to the outside.
The washer is complete but before going into Object Mode
we need
to set the cursor ready to add the final component.
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loop of
vertices on the left hand side of the washer and snap the cursor to the
centre of these. Shift-S
Cursor>Selection. Tab into Object Mode
and in the Link and Materials panel rename the washer OB:6mmWasher. |
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The next thing
needed is to model the M6 nut. Some consideration should be given to
how many vertices to use for the nut, as the external hexagonal section
will only require 6 vertices and internal circle will require more.
Some extra detail on the external profile will be required to form the
curves on the top edge of the nut so it would simplify the modelling to
keep the same number of vertices on the outer and inner diameter.
Six
vertices should be enough to form the curved detail on the top of the
nut so with six sides this equates to an inner circle of 36 vertices. |
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In front view NumPad 1 press the Spacebar to open the
Toolbox and add a
Circle with 36 vertices and a radius of 3
Add>Mesh>Circle.
Now
add a circle with 6 vertices and a radius of 5.7735 This will form a
hexagon with 10mm across the flats. With the 6 outer vertices still
selected, subdivide each edge of the hexagon with 5 vertices, W
Subdivide Multi. Change the number in the popup menu to 5 and press OK
to accept.
Select All
and fill the space between both loops of vertices with faces Shift-F.
To improve the fill pattern and remove the long thin triangles press Alt-F (Beautify
Fill). Repeat the beautify fill command several times until the
internal edges no longer change.
To convert the triangular faces into quads press Alt-J. |
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Blenders
beautify fill attempts to produce triangles with the shortest possible
sides and has overcompensated on the corners of the nut. If left like
this the mesh would produce ugly edges when bevelled. It's worth
manually rearranging these corners to form quads.
In
edge select mode Shift-RMB
select the two edges indicated and delete them X (Edges). |
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In vertex select mode
select 4
vertices (A, B, C, & D) and insert a face F, select the next
four
vertices (C, D, E & F) and add the next face. The corner will
now
have a much better face pattern. Repeat this until all 6 corners are
done.
To make modelling easier we need to rotate the nut so two flats are
parallel to an axis. Select All
and Rotate -15 degrees.
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To make the side
faces of the nut Shift-RMB select the seven vertices of the top edge
and Extrude them Y -4.
To form the radius on the
top of the side face we need to spin a |
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centre vertex. Select the vertex indicated and snap the cursor to it. To
determine the angle of the spin, with the centre vertex still selected Shift-RMB
select the two vertices on the corner of the opposite edge and
temporarily form a triangular face. With the face selected click on the
Edge Angle button of the Mesh Tools 1 panel. The corner angles of the
triangle will be displayed in the view. The spin angle is 71.635
degrees. Press Ctrl-Z
to remove (undo)
the triangle | |
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In top view NumPad 7
select the bottom right hand vertex indicated and in the Mesh Tools
panel set Degr: 71.635 and Steps:6.
Press Spin and the ark at the top edge of the face will be formed.
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Shift-RMB select two
corresponding vertices and merge them together Alt-M
at the vertex point on the ark. The selection order will determine
whether you choose "at first" or "at last" from the popup menu.
Merge the rest of the vertices on the top edge of the nut face to the
ark using this method. |
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Shift-RMB select all the
vertices on the side face of the nut, then Tab into Object Mode.
Snap the cursor to the object centre Shift-S Cursor>Selection.
Tab back into Edit Mode.
In the Mesh Tools panel set Degr:360 and Steps:6, press Spin Dup and the
other sides of the nut will be generated.
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Select All
and Remove Doubles W. |
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Alt-RMB select the
inside diameter of the nut and Extrude
it on the Y-axis
-5mm,
then extrude it on the Y-axis a further 1mm.
Snap the cursor to the centre of the last loop of vertices.
The extra loop of vertices will allow us to set a different material
for the nylon insert of the nut.
Select the centre vertex of the ark on the top face of the nut and
extrude it on the Y- axis. |
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Check the Pivot Point is
still set to 3D Cursor and Scale
the vertex on the Y-axis
to the cursor position 0. |
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The above scale has set
the vertex level to the top edge of the nut, but this edge needs a
0.5mm fillet radius. Grab
the vertex and move it Y
0.5,
then extrude it on the Z-axis -0.5 to set the centre of the fillet.
Snap the cursor to this vertex, then select the previous vertex.
In the Mesh Tools panel set Degr:90 and Steps:5 and Spin the fillet
radius.
To form the profile of the nylon insert we need to move the inside
diameter back slightly. |
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Alt-RMB select the
inside diameters top loop of vertices and move it G on the Y-axis 0.5mm. |
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To complete the top profile of the nut extrude the top vertex of the
inside diameter to the dimensions shown, constraining to the required
axis and dimensional input.
Form the chamfer by Extruding
the vertex Y
-0.25
then Grabbing
this vertex and moving it Z
0.25
Shift-RMB
select the end of the fillet radius and join it to the chamfer with an
edge F.
Shift-RMB
select the 11 vertices of the top profile.
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Go into front view NumPad
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In the Mesh Tools panel
set Degr:360 and Steps:36 and Spin the top profile.
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We
are now left with a series of breaks in the mesh between the top
profile and nut sides. To keep the mesh organised its best to manually
fill these areas.
Select 4 vertices (3 on
the corners of the openings) corresponding to where a face
should be and press F
to insert a face. Continue around the perimeter of the nut until all
faces are filled. |
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In
Edge Select mode Alt-RMB
select the bottom edge of the nut, then Shift-RMB select the
6 corner edges. We will add a 0.1mm chamfer to these using |
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Centre script described in 608
Part-4. |
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Select All, Remove Doubles W, Set Smooth W and Calculate
Normals to the outside Ctrl-N. |
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To
finish add an Edge Split modifier, but because the edge angles are 30
degrees the same as the default settings for the modifier, ugly shading
patterns will be created on the corners of the nut. Change the angle
setting to 29 degrees to overcome this problem.
In the Link and Materials panel change the name to M6NylocNut
Tab into object mode and in the Outliner bring the other objects into
view.
Save your work Ctrl-W. |
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I
hope you have
found this a worthwhile exercise. The intention was to demonstrate how
components can be modelled together in assemblies using one component
to help set the location and surface geometry of the next, using
Blenders Snap tools to
accurately locate the new Object.
Part 3 will detail how to use Blenders Screw tool to generate a thread
profile
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