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Written |
These materials are © 2001 PTC |
Conditions of use |
Copying and use of these materials is authorized only in the schools of teachers who attend official training and have received a legal site license.. All other use is prohibited unless written permission is obtained from the copyright holder. |
Acknowledgements |
John Hutchinson - The College of New Jersey
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Feedback |
In order to ensure these materials are of the highest quality, users are asked to report errors to the author. Suggestions for improvements and other activities would also be very welcome. |
tim.brotherhood@staffordshire.gov.uk
Razor Scooter – Intermediate level 1
Educational Objectives of the Unit
To complete a complex assembly with components created using the revolve feature. Mechanical features of the model are then explored using kinematics.
Students will be able to:
· employ further sketching techniques including construction lines, mirror.
· create components using the Revolve feature.
· assemble components to allow kinematic motion.
· create mechanical movement by dragging components on screen.
In each of these tutorials we introduce new techniques for using Pro/DESKTOP and aspects of designing that significantly impact on the type of product being developed.
Assemblies can easily be created from components modeled in Pro/DESKTOP. This tutorial uses the popular Razor Scooter as the focus to learn about and explore aspects of design practice as well as extend existing skills. The tutorial will focus on the Revolve feature.
Design
must take into account many things.
Function, form (shape), fashion, safety and many other factors affect
the final product.
A designer must balance these requirements with cost and availability of materials, manufacturing processes and the customers’ wishes.
Successful products will address many of these directly and provide users with products that are efficient and pleasing to use.
Classic designs on the other hand go beyond this and become part of the culture they were created in.
The Razor scooter is a good example of a luxury item that has recently enjoyed renewed popularity with young and old.
The child’s scooter has been around for a long time. Examples of Victorian scooters can be seen in museums and as recently as the mid 1900's children would be seen playing with them in most suburban streets.
Pics
Scooters have been out of fashion for some, partly due to the competing development of the bicycle. Many variations of the bicycle have been produced including choppers, BMX and mountain bikes.
Pics here
The modern style scooter became popular in the first year of the new millennium and is characterised by the very small wheels borrowed from in-line skates.
The style was popularised by one company, Razor.
Their use of modern ‘high tech’ materials such as aircraft quality aluminum and engineering to close tolerances has contributed to the Razor being seen as a ‘must have’ item by children and some adults who feel they want to make a fashion statement.
Design considerations
Compact, folding, clean, robust, silent, comfortable on smooth surface (town) not suitable for rough surfaces
The scooter is now finding its way into competitions with tricks in the tradition of skateboards, BMX bikes and in-line skating.
Designing products that ‘fit’ humans is know as ergonomics. This field was pioneered by Henry Dreyfuss (19**-19**), an industrial designer who collected an enormous amount of information about the human anatomy relevant to design. He and the people who worked for him measured thousands of people and tested them for how much pressure they could exert by pushing and pulling and how well they could read signs and dials from a specific distance. They measured the distance from the bottom of the foot to the underside of the leg of people while sitting, and they measured how far they could reach without stretching. They took many, many other measurements. This data, compiled for all sizes and shapes of people, is called anthropometric data and the study became known as anthropometrics.
Henry
Dreyfuss used statistics to compile tables that would make the information
collected useable. He broke the
population down into men and women, children of different age groups, people
seated and people standing, people in wheelchairs, and many other categories.
You will recall in your mathematics studies, characteristics of populations typically fall in what is known as a normal or Gaussian curve. If we look at the size of the feet of an 25year old male, we would see that they have an average (mean) shoe size of 9. You will also remember that in a normal population the mean, median and the mode are all at the same place. The mean is the average , the median is the middle of the population (half of the population is below and have is above) and the mode is the most frequently occurring something. So, according to the chart, most men take a size 9 shoe. Those who take a shoe size larger or smaller are fewer in numbers. But about 68% of men take a shoe size between 7 and 11. Those who wear shoes smaller than size 7 and larger than size 11 fall into the extreme lower or upper areas of the graph and therefore represent smaller percentages of the population. Shoe companies do not get rich making men’s shoes in size 4 or 14 because there are very few people who have feet that size. If you want to make money selling shoes, you make them in the sizes that most people wear. Also, if you want to design something that fits most people, you design from data that tells you that it will fit most people or that most people can use it.
How
about chairs? The distance from the bottom
of your foot to the underside of your thigh (while you are in a sitting
position) represents a measurement that will help you design a chair that is
comfortable for you (P in the figure below).
But if you are going to mass produce chairs and sell them to the public
you will want to design a chair that is comfortable for everyone. But you can’t. Some people who are short will demand a chair that will be much
too close to the floor for the “average” person. And someone who is tall will want a chair with the seat
higher. So what do you do?
The anthropometric data that Henry Dreyfuss compiled provides you with information that can help. In the chart below, you will notice two numbers for the measurement mentioned earlier, one to the left of the dimension line and one to the right. The measurement on the left represents the lower 2.5th percentile and the one on the right represents the 97.5th percentile. ??
(insert graphic of data)
Dreyfuss used this data in his design work. For example, he redesigned the interior control layout for a military tank, a place where the operator needs to be able to reach everything easily and quickly and not mistake one control for another during the stress of battle. He designed tractors and thermostats and many things in between. Anthropometric data can help you design almost anything that humans use, and humans use almost everything that technology creates.
Understanding Materials
An understanding of materials is vital in order to design products. We all experience materials in everything we do. We know that most metals are hard, thin strips of wood are flexible and plastics make excellent containers for a wide range of liquids.
Illustrations of a tank, longbow and plastic containers.
Properties
It is the properties of materials that make them suitable for certain products. No one would dream of making a coffee cup out of chocolate or car tires from glass!
Illustrations of a chocolate coffee cup and glass tire?!
Materials in schools
The materials commonly found in schools for students to work with fall into three main groups, plastics, metals and wood.
Pro/DESKTOP is well suited to modeling and machining all three of these materials with suitable equipment.
Rapid prototyping
Rapid prototyping systems sometimes use other materials you would not normally associate with engineering including cornstarch and plaster. A later tutorial on CAM explores the processes and materials used in rapid prototyping in more detail.
Razor scooters are made predominantly from aluminum. The reasons for this could be complex. The lightweight and strength may be the reasons aluminum alloy was chosen. The ability to mold and machine aluminum could have been a factor in the choice. We should not forget that fashion plays a significant part and the high tech image of aluminum probably influenced the choice. So what is aluminum and where does it come from?
Aluminum is extracted from bauxite, the most common material on planet earth! Bauxite is a mixture of pure aluminum, rock, other minerals and impurities. It must be refined in a furnace to extract the pure aluminum.
This is not the end of the story. Pure aluminum has certain properties but by alloying it with other materials these properties can be altered. ??? is added to increase the tensile strength. Small amounts of copper can be added to make the aluminum alloy more ductile.
Aluminum like other metals and thermoplastics can be formed in a number of ways. Standard sections can be extruded and complex shapes cast.
Pictures of extruded section and an aluminum casting from razor
6061, aluminum is used extensively to build aircraft. It is hard wearing and has a high tensile strength. These properties are very beneficial for building aircraft but there is usually a downside. The hard-wiring property of ??? aluminum makes it difficult to cut using conventional cutting tools when creating parts.
To get around this problem new cutting techniques have been developed including laser, flame, abrasive water jet, etc. These enable aluminum and other hard materials to be cut quickly and accurately.
Many of the components for the Razor scooter assembly have been provided for you, particularly the parts that use the extrude feature you have already learned about in the Quick Start unit.
The new feature introduced for the first time in this tutorial is Revolve.
This can be likened to the holiday decorations that start out as a flat half bell shape and open out to create a complete three-dimensional bell.
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Picture here |
Picture here |
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Folded bell |
Opened out Bell |
Remember, in Pro/DESKTOP a revolved shape requires two sketches, an axis sketch with a single straight line and a profile sketch of the shape of the object. These sketches should be on the same workplane.
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Axis sketch Profile sketch |
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Sketches |
Sketches |
Completed revolve |
The tire on a Razor is molded onto the hub. This produces a very secure join between hub and tire.
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You will create the tire and hub components using revolve and project features. These will then be assembled to form the completed wheel sub-assembly.
The hub has been started for you. This time, millimeters will be the units used for the model.
· Open the file called hub.des in the “Wheel assembly” folder
Bearing housing
Construction lines have been created to locate key aspects of the design and lines representing the bearing housing at the center of the wheel.
The Frontal workplane contains two sketches. An Axis sketch with a single line and a sketch called Hub Profile that is incomplete. You will complete the profile sketch in order to Revolve the wheel hub.
The Profile sketch may not be active (bold in the workplane browser).
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The Browser will be showing workplanes and the Frontal workplane should be bold showing it is the active workplane. · Click on the + sign next to the Frontal in the browser. You will be able to see a list of sketches including Axis and Hub profile. ·
From the design toolbar select |
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· Double click on one of the lines around the bearing housing. (See diagram above) Look in the browser and you will see that the Hub profile becomes the active sketch (bold on the workplanes browser). You are now ready to draw lines to complete the hub profile sketch. |
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Use 
, the Straight-line tool to complete the Hub
profile like this. (New lines have been highlighted in red).
Mirror linesSo far only half of the rim shape has been drawn. The mirror tool will be used to create the other half. ·
Select · Lasso the lines shown. (Dotted lines show where to drag the lasso). |
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The lines will highlight in red.
· Open the Line pull-down menu
· Click on Mirror…
picture on left should say 10 lines
The Mirror Sketch Lines
dialogue window opens.
The mirror tool expects you to select two things. The lines to be mirrored, and the axis for the command. Because you made a selection before starting the mirror tool these will be used for the Lines.
· Click on the Axes tab in the floating dialogue box.
· Click to select the vertical construction line.
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With the Axes tab active, click to select this line. |
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·
Click on 
.
You will now revolve the sketch to create a wheel hub
·
Click on 
, the Revolve Profile tool.
The Revolve Profile... dialogue window opens.
· Make sure the correct sketches are selected for profile and axis
· Type in 360 for the Angle
·
Click on 
The wheel will revolve. A Trimetric or Isometric view will give you a clearer idea of what the hub looks like. Save file.
The F9 - F12 keys on the keyboard dictate how the model looks. The view above is called enhanced and is set using the F12 key.
Try the other three view keys.
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F9 - Wire frame |
F10 - Shaded |
F11 - Transparent |
These choices are also available in the View pull-down menu.
Modify ProfileThe genuine Razor wheel is more complex than the one that your are designing here. The profile has a curved outer surface and the hub has holes running through it sideways. |
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The Hub profile sketch should still be active (bold in the workplane browser).
· Change the view to Onto Workplane (Shift + W)
· Autoscale (Shift + A)
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·
Select · Move the mouse cursor into the position shown in the diagram on the right until the two intersecting lines are highlighted in cyan (light blue). |
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· Click and drag with the left mouse button until a small fillet appears. · Release the mouse button. ·
Click on |
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You may already have realized we have only changed one side of the wheel. There are a number of ways to match the other side but you will use the mirror tool for practice.
Delete unfilleted lines·
Activate · Drag a lasso to select the two sloping lines on the left side of the profile. · Delete the selected lines. |
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· Lasso the lines on the right to be mirrored.
There may be a very small straight line next to the fillet arc. Make sure you include it in the selection
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· Open the Line pull-down menu
· Click on Mirror…
The Mirror Sketch Lines dialogue window opens.
The lines to be mirrored were selected before starting the mirror tool
· Click on the Axes tab in the floating dialogue box.
· Click to select the vertical construction line.
·
Click on 
.
The profile is now valid again.
·
Update the model using the 
tool.
Both sides of the hub should now be curved.
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Hint: As an alternative to using a lasso, you can manually add (or remove) lines from a selection by holding down the shift key when clicking on additional lines. You will need to zoom very close to use this technique. |
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The holes in the hub are there so that the tire will grip the hub and the tire and hub will spin as one unit. The tire is actually molded right on to the hub during manufacture, and the hot plastic of the tire runs into the hub and makes a very secure connection.
We will use a new 3D tool, Project Profile to make the holes in the hub. The sketch will be created on the Lateral workplane that runs perpendicular to the Frontal workplane we have used so far.
· Makes sure you can see the Lateral workplane listed in the browser
· Right click over the name Lateral in the browser
· Select New Sketch from the floating menu
· Name the sketch Rim holes
·
Click on 
The new sketch will be active (bold) in the workplane browser.
View Onto Workplane (Shift + W) and Autoscale (Shift + A)
Drawing construction lines·
Use Tip: Lines are first drawn solid. · Right click on a line and select Toggle Construction to convert the line to construction. |
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· Click on the vertical construction line to select it (turns red).
· Open the Constraints pull-down menu and select Toggle fixed.
· A small triangle attaches itself to the line to show it is fixed.
· Use the same method to fix the horizontal construction line.
Adding constraints·
Use the · Add an angle constraint between the vertical and angled construction lines. ·
Activate · Double click on each constraint in turn and change them to the values shown. |
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Drawing the holes· Zoom in to the top half of the hub. ·
Use the ·
Use the · Create a similar circle at the intersection of the angled construction line and the pitch circle. |
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Pro/DESKTOP simplifies your work by allowing you to perform many tasks interactively using a single tool. When you prehighlight a linear object, you have the choice of snapping to attraction points at the endpoints, middle, or along the object.
There are two sizes of attraction point. Very small black squares indicate a point on an object that is near the pointer. Larger black squares indicate an endpoint, midpoint, centerpoint, or intersection.
In creation mode, when
you prehighlight an object an attraction point is generated. If you click and
drag in this state, the new object anchors at the attraction point, and a
constraint is generated. In modification mode, objects can be dragging to snap
attraction points to ones on another object.
Note: When you create objects using attraction points, a constraint is created, indicated by a black box at the coincident point.
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·
Attraction
point Tip: To make sure there is an attraction point at the intersection of the small circle and the vertical construction line place the Circle tool over this intersection when drawing. |
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Attraction point
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·
Again look for the attraction point at the top of the small circle. |
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·
Use · Makes sure you delete the bottom half of the large solid circles. |
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Note: The diameter constraints on the small arcs have turned bright green. This signifies that recent changes to the design have added constraints making these redundant. Leaving them will not be a problem for the model. Deleting one of the diameter constraints will, however, simplify the design screen.
Click on 
, The Revolve Profile tool.
Complete the dialogue window like this
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·
Click on The slotted hole has been projected through the hub removing material. To create slots all around the hub we can use a new tool called Duplicate to repeat the original around the origin. |
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· Make sure the Through holes sketch is still active.
· Zoom Onto workplane and Autoscale.
·
Use the 
, tool to
select the four arcs that make up the slot.
· Open the Edit pull-down menu
· Click on Duplicate…
The Duplicate dialogue window opens
·
Click on the Circular tab
·
Enter 12 for the Number (of
repeats)
·
Leave the rest of the options as they
are and click on 
.
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The Duplicate command operates on the selected lines when the tool is
started. The position of the origin
(intersection of the green arrows) is used as the center for duplication. ·
Update the model using the Hint: The origin can be relocated using an option in the Workplanes pull-down menu. ·
Save your hub design |
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Creating additional holes through the hub is one of the extension activities suggested at the end of this tutorial.
This is the profile sketch and tire you will produce in this section.
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Profile sketch
(Axis line hidden) |
Finished tire |
The tire is much simpler to create than the hub but you will use a new technique to do this that involves starting a new design from inside an existing component. The technique is called designing 'in context'
· Makes sure your hub is open on screen.
· Make sure the Hub Profile sketch on the Frontal workplane is active (bold in the workplane browser). Shift-W to view onto workplane.
The active sketch defines which direction the new design will be facing when first created.
· Open the Assembly pull-down menu
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· Select the New Part in Context option. A new design window opens with a ghosted version of the hub visible in the background. This makes it easy to create the new component to the correct size to assemble with the exiting part. |
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· Draw a horizontal line for the axis of the tire. You have drawn this line on the Initial sketch on the Base workplane. Renaming the sketchThis helps to keep things clear for later work. |
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·
Right click over the Initial sketch
·
Select Properties from the
floating menu
·
Change the name of the sketch to Axis
·
Click on 
.
· Right click over the Base workplane
· Click on New sketch in the floating menu
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· Name the sketch Tire profile ·
Click on |
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· Zoom in to the area at the top and above the rim of the hub.
·
Use 
, the Straight-line tool to draw a vertical
center line.
· Right click on the line and choose the Toggle construction option.
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·
Use ·
Use · Open the Constraint pull-down menu and select Toggle fixed. (Ctrl + F keys on the keyboard will also fix highlighted lines). |
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Completing the tire profile sketch· Use the circle tool to draw three circles like the ones on the right. Draw one large circle and then use the mirror command to make the second. Use the center line as the axis. Note: The large circles should attach to the tops of the short vertical tire wall lines. The small circle should be attached to the vertical centerline. The next section shows how constraints (in this example, tangents) can be applied to existing lines. |
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·
Use the ·
With · Change the value to 15 mm. ·
Click on |
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·
Activate 
, the Select lines tool.
· Select one of the large circles
· Holding down the Shift key on the keyboard click on the small circle to add it to the selection
With the two circles selected, a tangent constraint can be applied.
Applying a tangent constraint· Open the Constraint pull-down menu · Choose Tangent from the menu. The small circle will move up along the centerline until it fulfils the tangent constraint. Repeat for other large circle. |
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Deleting unwanted lines· Select the Delete line segments tool · Remove lines to leave the tire profile. Tip: Use the Toggle sketch filled option in the Line menu to indicate when the sketch is valid. |
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If you have problems with the sketch, zoom in to see if there are small sections of the large circles remaining. Look for these small sections at the rim position. With a valid profile the tire can now be revolved. |
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·
Select 
, the Revolve Profile tool.
· Make sure the correct sketches are selected for axis and profile.
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·
Change the angle to 360 degrees and
click on ·
· Save your tire model as Tire.des The next section is intended to give you practice finding and correcting problems with sketches. After that you will be shown how to assemble the tire and hub to create a wheel. |
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1. Name three restrictions that commonly affect a design.
2. Give two reasons why designs become 'classics'.
3. List two differences between the old style scooter and the Razor.
4. What ProDESKTOP 3D feature was used to create the Razor tire?
5. What is the minimum number of sketches needed to create the tire?
6. How many lines can there be on an axis sketch?
7. Give two ways to make a different sketch active.
8. To create a symmetrical sketch you first drew half of the profile. Which tool from the line menu did you then use to create the other half of the sketch?
9. Suggest two modifications to the Razor hub to make it more interesting to buyers. One should focus on the shape or form of the hub and the other on materials.
10. How do you add (or remove) a line to a selection?
11. How is a solid sketch line changed into a construction line (or back again)?
12. How do you fix a line so it cannot move?
13. What is ProDESKTOP telling you when an attraction point is seen when drawing a sketch line?
14. Describe one difference between the project and extrude features.
15. What does the duplicate - circular tool allow you to do?
How is a tangent constraint applied to two existing sketch lines?
Sketching is a fundamental part of modeling in ProDESKTOP. Finding and fixing problems with sketches is usually straightforward but can be quite tricky. As you become competent with this your productivity will increase significantly.
For a sketch to work as profile for extrusions, revolves and sweeps it must be a closed loop of lines with no gaps or overlapping lines.
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Valid |
Invalid |
Invalid |
In the examples above it easy to spot why the second and third sketches are invalid sketches.
If only things were always that easy!
The first design is an invalid sketch because it has a very small break in the perimeter line.
·
Open
the design file Gap 1.des in
ProDESKTOP.
At first sight this rectangle looks fine. However, if you tried to use it as the basis for an extrusion the following error would appear.
Although the language is not that friendly, where it says, "…the profile is not enclosed…" gives a clue that the sketch may have a break in it.
Look again at the sketch.
Notice there is a very small dot at each corner, except for
the top right.
·
Zoom in on that corner.
It looks fine.
Zoom in again on a very small area where the lines 'join'.
The smallest gap will make the sketch invalid. The rectangle is 100mm long and the gap is only 0.48mm!
Drawing an extra line to bridge the gap is a simple solution.
·
Select 
, the line
draw tool.
· Carefully draw a line across the gap.
Once you have closed the gap, prove it is a valid profile by extruding the rectangle to create a cuboid.
Close the file without saving.
There is more than one way to fix the open rectangle. This time you will move the end of one line to coincide with the other.
·
Open
the file Gap 1.des again in
ProDESKTOP.
· Zoom in so that you can see the gap on screen.
·
Select 
, the Select line tool.
· Click on the horizontal line to select it.
· Hold down the Shift key then click and drag the end of the horizontal line to the right until it meets the top end of the vertical line. (This technique of extending a line is very useful).
Having closed the gap, extrude a cuboid to prove the sketch is a valid profile.
Close the file without saving and you will be able to use it again for this exercise.
· Open the file Gap test.des.
· Find and close the gap at the corner.
The sketch is still not a valid profile. There is another gap but not at the corner. Here is how to find it.
Make sure 
, the Select lines tool is active.
Move the mouse cursor over the lines in the sketch.
Each line will pre-highlight in cyan. Lines that appear to be a single line will pre-highlight as two separate sections.
Hint: When you find the break it is often easier to delete the two sections and redraw as a single continuous line.
Duplicate lines are more difficult faults to find and cure.
· Open the file Duplicate 1.des
The sketch looks like a plain rectangle. This time there are small squares on all corners suggesting these are all joined.
If you try to extrude this shape the following error appears.
This time the error message suggests there may be overlapping lines.
You may also have noticed that a checkered pattern appeared along one of the lines in the sketch when you tried to extrude.
ProDESKTOP has highlighted the overlapping lines for you. You can cancel the extrude and the offending line will then be highlighted, ready to be deleted.
·
Click on 
, the Select Lines tool.
· Click to select the bottom line.
· Press the Delete key on the keyboard.
The highlighted line will disappear. There will still be a line in that location. This may be another duplicate. A reliable way to ensure the remaining line is the last one in that location is to keep highlighting and deleting lines until a gap appears then undo immediately. Here is how to do it.
· Click to select the bottom line again.
· Press the Delete key on the keyboard.
Did the line disappear?
· If so, immediately click on undo to reinstate the line.
On a complex profile you may need to do this for each line segment before you can be sure there are no more overlapping lines.
Try this out to find the duplicate line in the file called duplicate test.des
Beware there may be more than one duplicate line!
The first time this happened to me I thought that I had lost everything!
· Open the file lost 1.des
It looks like a blank workplane. Look carefully at the origin and you will notice two small black lines. This indicates something is drawn there.
· Zoom in very tightly on these small lines.
Hint: You may need to zoom more than once.
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First zoom |
Second zoom |
Nothing appears to be wrong with this sketch and yet any attempt to extrude will fail.
· Open the View pull-down menu and select Autoscale.
The view returns to the seemingly blank screen. For the next part you will need very good eyesight and a clean monitor screen!
We know the circles are located at the origin so why does the view zoom out dramatically when Autoscale is used?
· Look very carefully near the corner of the workplane diagonally opposite the green origin arrows.
The workplane is the green rectangle. Remember it sizes automatically to surround everything that has been drawn.
Can you see a very small dot in the top right hand corner?
·
Click on 
, the Select lines tool
·
Lasso the small dot to select it. (It is too small to reliably click on to
select).
· Open the View Pull-down menu
· Select Autoscale Selection…
The lost line fills the screen!
· Delete the line
· Autoscale the view
The circles should now fill the design window. An attempt to extrude the sketch will create a thick walled pipe.
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· Now have a go at finding the lost line(s) in the file called lost test.des
The previous example shows it is possible to have an 'island' inside a profile to create a solid with a hole.
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It is also possible to create multiple holes when extruding a solid. |
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You cannot however have islands that overlap each other or with an outer perimeter line.
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Invalid Profile |
Invalid Profile |
Invalid Profile |
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Correcting this fault is straightforward. Open the file Overlap test.des and remove overlapping islands until the file will extrude successfully.
There is almost no limit to the number of islands you can have but you cannot have islands inside islands.
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Valid profile |
Invalid profile |
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· The file called Island 1.des will give you an opportunity to delete an island to create a valid extrusion sketch.
For the Revolve and Sweep features the profile and axis lines must be on separate sketches.
Axis sketch Profile sketch
Revolved (turned) solid
A common problem occurs when the axis is accidentally drawn on the same sketch as the profile. In this section you will be shown how to find out which sketch the axis line was drawn on and how to move it onto a different sketch.
· Open the file Revolve 1.des
· Make sure the browser is listing Workplanes.
· Click on the + next to Base to show sketches on this workplane.
There should be two sketches, outline and axis. You will notice that the axis sketch is missing. This is a clue to the likely cause of the problem. It also highlights the importance of using sensible names for sketches, workplanes and features.
· Right click over the Base workplane name in the browser.
· Select New Sketch from the floating menu.
· Change the sketch name to Axis.
·
Click on 
.
This is very easy.
·
Make sure 
, the Select line tool is active.
· Double click on the axis line.
The sketch for that line will become the active sketch in the browser. In this case the active sketch will show as Outline. Is this what you expected?
Hint: If the sketch for the line selected is already selected, a dialogue window will open to show the properties of the sketch.
·
If this happens Click on 
to close the window without making changes.
Notice that the axis line is on the Outline sketch and it will need to be moved to the newly created Axis sketch.
ProDESKTOP has a clipboard like other Windows applications and it is ideal for transferring lines to another sketch. However, the ProDESKTOP clipboard will only operate inside ProDESKTOP. You cannot use it to copy and paste to another application.
· The axis line should still be selected.
·
Click on 
, the Cut tool. The line will remain highlighted red and a hatched box will
surround it.
· Right click over the Axis sketch name in the Workplane browser.
· Select Activate sketch from the floating menu that appears.
·
Click on 
, the Paste tool.
The axis line has now been pasted on to the axis sketch.
The design should now revolve successfully to create a solid.
Hint: When doing the Revolve, remember to select the correct sketches in the profile and axis options in the dialogue window.
1. Name two reasons why a sketch may not be a valid profile for creating a 3D feature.
2. How would you find a break at the join between two lines?
3. How would you look for a break in a straight line?
4. List two methods of closing a gap in a sketch.
5. When attempting to create a 3D feature ProDESKTOP produces an error message. At the same time a line in the profile sketch is highlighted as a black and yellow checkered pattern. What is the significance of this?
6.
What is likely to be the cause when
ProDESKTOP zooms out drastically and appears to 'lose' your sketch lines when
Autoscale is selected?
7. Which of these are valid profiles for creating a 3D feature?
8. How can you find out which sketch a line is on?
9. An axis line has accidentally been drawn on a profile sketch. List the key stages in moving the line onto an axis sketch.
Tip: Assemblies should start with a blank design and all components added to the empty design. This makes it easier to modify individual components. However, in this case you have created the tire by the command New Part in Context. When you did this, the hub then automatically became the assembly file. When you switched back to the hub.des file you should see both the hub and the tire.
If you select the hub with the Select Parts tool it will not move. This is a characteristic of using a part file as an assembly file. But since the tire was assembled into the hub file, the tire may be selected and moved.
Two constraints will be added, the side faces will be aligned and the rim and tire will be centered.
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·
Aligned · Click on the side of the tire to select it. It will be shaded red. · Hold down the shift key and click to select the side face of the hub. It will be shaded red. · Open the Assembly pull-down menu and select Align. |
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The tire or hub will move until the surfaces are aligned.
Tip: The Align tool will be grayed out (unavailable) unless two surfaces are highlighted.
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§
Select § Click on the cylindrical surface on the rim of the hub. It will be shaded red. § Hold down the shift key and click to select the inside cylindrical surface of the tire. It will be shaded red. § Open the Assembly pull-down menu and select Center axes. |
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The tire and hub will now be properly assembled.
Note: You may also center cylindrical objects and holes with the Select Edges tool.
· Open a New Design file and save it as Wheel sub-assembly.des
Bring in the hub.des file. You will now use this file for the remainder of the wheel assembly. Make sure it is saved in the Wheel assembly folder.
·
Wheel bearing.des Bearing
spacer.des
Use the techniques just learned to assemble
two bearings and a sleeve into your wheel.
Wheel bearing.des Your wheel
sub-assembly
Each component will need two constraints: a center axes constraint and either a mate or align.
· Save your wheel sub assembly. You will add it to complete a razor scooter later!
Models frequently need holes for assembly purposes. ProDESKTOP has a feature that will create holes that comply to international standards very easily.
· Open the file Lower clamp ring.des
· Click on the + next to the side of part workplane.
· Right click over the side hole sketch.
· Select Activate Sketch from the floating menu.
·
Click on 
, the Select lines tool if you cannot see the
lines.
The circle for the hole has already been drawn. We could simply extrude the circle through the model removing material to create a hole. In this case however we need a counterbore to fit the head of a hexagon head machine screw.
Pro/DESKTOP will do this in one go.
·
Click on 
, the Insert holes tool.
· Select Counterbore.
· Make sure the options match the ones above.
·
Click on 
.
The couterbore is created through the first half of the
clamp.
The hole in the other side of the split in the clamp should
be threaded.
· Right click over the side of part workplane.
· Select New sketch from the floating menu.
· Name the sketch Threaded hole.
·
Click on 
.
· View onto workplane (Shift + W).
· View Autoscale (Shift + A).
Draw a circle centered on the existing hole.
Constrain the circle to 4mm diameter although the size of the circle does not have to be the same size as the hole feature.
·
Click on 
, the Insert holes tool.
· Select Simple for the hole type.
· Make sure the other options match the ones above.
·
Click on 
.
· Save the clamp as Finished lower clamp ring.des
The clamp sub-assembly is made up of the clamp itself and a socket head machine screw. Remember assemblies should start with a new empty design.
ProDESKTOP assemblies can be moved by dragging components on screen. However sub-assemblies will not move in the final assembly.
Steering
head component Deck
subassembly Folding bracket Wheel
subassembly Wheel
Deck
Rear fork
Hub
Bearings
· Start a New design (for the lower clamp assembly)
· Open a small Explorer window on top of Prodesktop.
· Drag each component from the list in explorer into the design window.
They are now ready to assemble.
· Zoom in so that you can see both components
·
Use the select face tool 
.
· Select the underside of the socket screw head.
· Add the bottom of the counterbore to the selection (Shift + click).
You could use the assembly menu and mate like you did with the wheel.
An alternative is to use the right mouse click menu. Most windows software supports right mouse click menus. They are also called context sensitive menus. This means the menu is made up of options that apply to whatever is highlighted when the right mouse button was pressed.
Assembly with right mouse button· With the two surfaces selected, right mouse click. · Select Mate from the floating menu. The bolt and/or clamp ring moves to comply with the mate assembly constraint. |
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· Click on a clear area of the screen to cancel previous selections · Multiple-select the cylinder of the bolt and the hole through the clamp · Right click and choose Center axes from the floating menu. |
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The bolt and clamp are now fully assembled. |
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The two constraints hold the bolt firmly in the clamp. It should however be possible to revolve the bolt!
·
Click on 
, the Part select tool.
· Select the bolt.
· Click on the perimeter of the bolt and try to turn it by dragging.
The whole assembly is probably moving on screen making it difficult to turn the bolt. When moving mechanisms dynamically on screen one component should be fixed.
·
The Part select tool 
, should
still be selected.
· Click on a blank area of the screen to deselect the bolt.
· Click to select the clamp ring.
· Right mouse click to open a floating menu
· Select Fix component.
· Click to select the bolt
· Now try to rotate the bolt by dragging the edge of the bolt head.
Tip: Dragging in ProDESKTOP is a two step process. Click to select (object turns red) then click and drag in one operation.
Many of the assemblies for the Razor scooter have been done, leaving you to add your wheels to complete the model.
· Open the file Razor part assembled.des
· View the model in trimetric or isometric
· Open a small Windows Explorer window on top of ProDESKTOP listing your wheel design.
· Drag your wheel from Explorer into ProDESKTOP close to the rear fork.
· Drag a second wheel into ProDESKTOP close to the front forks
Zoom close in to the rear fork/ wheel.
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· Highlight these surfaces. · Right click. · Create a Mate constraint from the floating menu. Tip: You may need to zoom and drag the component back towards the rear forks for the next step. |
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· Highlight these surfaces. · Right click. · Create a Center axes constraint from the floating menu. |
|
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· The wheel will move into final position. · Use the Select part tool to highlight the wheel. · Click and drag the perimeter of the wheel to see it rotate! |
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Try moving some of the other components of the Razor. You should be able to unfold the steering column, turn the handlebars and rotate the wheels.
Remember: The sequence to move a component is:
·
Activate 
, the Select part tool
· Select the component you want to move.
· Click to highlight the component (turns red).
· Click and drag to move the component.
Tip: You may need to be wait for things to happen, particularly on slower computers.
Design challenges
With the knowledge and skills you have developed in this tutorial you could use Pro/DESKTOP to model new product designs of your own. Here are some ideas for new products you might explore.
Don’t be afraid to explore design ideas of your own.
Families take more and more equipment when going camping or for picnics.
Pictures of folding tables and chairs
Explore the design of portable seats and tables that would be strong, light but fold into a small size for storage and transport.
These come in a range of styles and sizes. Investigate existing designs.
Illustrations of walking sticks
Look for the unusual including shooting sticks and ones with built in refreshment (Whisky reservoir)! Look at Swiss army knives and leatherman tools for inspiration.
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See if you can develop a modern ‘high tech’ product.
Kites have been made for over 2000 years.
Chinese kites
In the 20th century the military used box kites for signaling and these had aluminum frames. The kites could be set up or put a way in seconds due to a clever folding system.
Box kite
Modern materials have developed that are light and very strong and modern kites come in many shapes and sizes.
Modern kites
Devise a kite that is strong, light and folds into a small package.
Lighting can be functional, providing light in dark areas or where fine work needs good levels of illumination. Or it can be decorative, helping to create a mood or atmosphere.
Pictures of a range of lighting types: up/down light, wall, center
rose,
Aesthetics play a major role in lighting design and the introduction of low voltage (12v) systems opens many possibilities to engage in product designs with a full scale working prototypes as the outcome.
Pictures of desk lamps
Desk lighting offers a wide range of design opportunities including adjustable lamps. An initial study of existing designs would provide a good basis for developing your own ideas. Pro/DESKTOP offers the ideal medium for modeling your ideas using assemblies and kinematics to explore, develop and refine ideas.
Quiz - Assembly
1. How do you start a new assembly?
2. Describe two methods of adding a component to an assembly.
3. Name the constraint you would need to add to make a piston slide inside a cylinder.
4. Suggest the constraint applied to this block.
5. Suggest the constraint applied to this block.
6. When trying to drag a component on screen, how do one you prevent another component in the assembly also moving on screen?
7. When creating a Counterbore hole, which dimensions will you need to specify?
8. Name two other types of hole that ProDESKTOP will create.
9. You create a sub-assembly of the hands on a clock and then assembled this into a clock final assembly. When you try to move the hands they won't move. What is the cause and solution for this problem?
10. How would you make a simple mechanism such as a pair of scissors 'move' on screen?
, the Select Lines tool.
, the Select Line tool.
, the Arc or Fillet tool.
, to
update the model wih the revised profile.
, the Select Lines tool
, the Line draw tool to draw these
construction lines.
, tool to
add a diameter constraint to the circle.
, the
Select constraints tool
, tool to draw a small circle at the
intersection of the vertical construction line and the large pitch circle
, tool to draw a large circle from the origin
(intersection of the two green arrows) to the bottom edge of one of the small
circles.
, Delete
line segment tool to remove unwanted solid lines until you are left with the
lines shown.
.
, the Straight-line tool to draw the lines
defining where the tire sits on the rim. (highlighted red in this
illustration) – one horizontal and two short vertical.
, the Select lines tool to highlight the
three lines.
, tool to
create a constraint on the small circle.
, the Select constraint tool selected,
double click on the diameter constraint.
.
, the Face select tool
, the Face select tool
