f1 r type c2

F1 in

Sch

ools

- ‘R

’ Typ

e

F1 in Schools R-Type Creo Parametric - Academic Editions

C2-AE-L2-004-1.0

PTC Academic Program

Creo Parametric F1 in Schools - ‘R’ Type page 2 of 91

Copyright © 2013 Parametric Technology Corporation. All Rights Reserved. Copyright for PTC software products is with Parametric Technology Corporation, its subsidiary companies (collectively “PTC”), and their respective licensors. This software is provided under written license agreement, contains valuable trade secrets and proprietary information, and is protected by the copyright laws of the United States and other countries. It may not be copied or distributed in any form or medium, disclosed to third parties, or used in any manner not provided for in the software licenses agreement except with written prior approval from PTC. UNAUTHORIZED USE OF SOFTWARE OR ITS DOCUMENTATION CAN RESULT IN CIVIL DAMAGES AND CRIMINAL PROSECUTION. User and training guides and related documentation from PTC is subject to the copyright laws of the United States and other countries and is provided under a license agreement that restricts copying, disclosure, and use of such documentation. PTC hereby grants to the licensed software user the right to make copies in printed form of this documentation if provided on software media, but only for internal/personal use and in accordance with the license agreement under which the applicable software is licensed. Any copy made shall include the PTC copyright notice and any other proprietary notice provided by PTC. Training materials may not be copied without the express written consent of PTC. This documentation may not be disclosed, transferred, modified, or reduced to any form, including electronic media, or transmitted or made publicly available by any means without the prior written consent of PTC and no authorization is granted to make copies for such purposes. Information described herein is furnished for general information only, is subject to change without notice, and should not be construed as a warranty or commitment by PTC. PTC assumes no responsibility or liability for any errors or inaccuracies that may appear in this document.

Written by Tim Brotherhood

and Dragos Vasilescu

These materials are © 2013, PTC. All rights reserved under copyright laws of the United States and other countries.

Conditions of use Copying and use of these materials is authorized only in the schools colleges and universities of teachers who are authorized to teach Creo Parametric in the classroom. All other use is prohibited unless written permission is obtained from the copyright holder.

Acknowledgements Proofing and comments – Peter Thompson.

Feedback [email protected]

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.

Product code C2-AE-L2-004-1.0

mailto:[email protected]



Contents Contents ......................................................................................................................... 3

Teachers’ notes .............................................................................................................. 5

Pre-requisites .............................................................................................................. 5

Downloading the tutorial files ...................................................................................... 6

Procedure one – Setting up key dimensions ................................................................... 7

Step 1: Opening the assembly .................................................................................... 8

Step 2: Changing key dimensions ............................................................................... 9

Procedure two – Concept design .................................................................................. 12

Procedure three – Modeling the body with Creo ........................................................... 14

Step 1: preparing the model ...................................................................................... 15

Step 2: Car body profile ............................................................................................. 17

Step 3: Nose side profile ........................................................................................... 24

Step 4: Reduce cockpit width .................................................................................... 27

Step 5: Rear wheel cutout ......................................................................................... 31

Step 6: Front wheel cutout ........................................................................................ 34

Step 7: Nose shape ................................................................................................... 37

Step 8: Shape the side pod ....................................................................................... 40

Step 9: Round the cockpit edges .............................................................................. 43

Step 10: Adding further rounds ................................................................................. 45

Step 11: Rear wing .................................................................................................... 47

Step 12: Mounting for front wing ............................................................................... 51

Step 13: Mirror the body shape ................................................................................. 54

Procedure four – Creating the front wings .................................................................... 56

Step 1: Modeling the Airfoil ....................................................................................... 56

Step 2: Create the mounting peg .............................................................................. 61

Step 3: Add a wing endplate ..................................................................................... 63

Step 4: Add rounds.................................................................................................... 65

Step 5: Creating a new mirrored part ........................................................................ 67

Procedure five – Part properties ................................................................................... 69

Step 1: Apply a material definition to the wings ......................................................... 69

Step 2: applying an appearance ................................................................................ 72

Step 3: Editing parameters ........................................................................................ 75

Procedure six – Mass analysis ..................................................................................... 77

Task 1: Mass properties analysis .............................................................................. 78

Procedure seven: Material density. ............................................................................... 80



Step 1: properties of the balsa blank ......................................................................... 80

Procedure eight – CNC manufacture your car body ..................................................... 86

Step 1: Exporting an STL file. .................................................................................... 87

Comparison of STL and Creo NC ............................................................................. 90



Teachers’ notes Context F1 in Schools is a multi-disciplinary challenge where teams of high school students use CAD/CAM software to design, analyze, manufacture and race small scale CO2 powered balsa wood cars. The challenge encourages students to learn about and utilize ICT, mathematics, science principles including physics, aerodynamics, design, manufacture, project management, financial strategies, leadership, teamwork, presentation, and apply them in a practical and efficient manner. This tutorial has been produced as part of the PTC Academic Program. It is an intermediate level 3D modeling activity providing students with an understanding of the design; engineering and scientific concepts used in the design of high performance race cars.

Important Note: This tutorial is NOT intended to provide students participating in the F1 in Schools Technology Challenge with a ‘definitive’ design solution, i.e. the fastest car. The aim of this tutorial is to provide students with sufficient understanding in the use of Creo Parametric to allow them to go on and model their own car design. Competition rules: Make sure you are very familiar with the latest rules from the challenge web site: www.f1inschools.com. Remind the students that design innovation often comes from what is ‘not’ stated in the rules.

Pre-requisites Before tackling this tutorial students must be familiar with the basics of part modeling, assembly, render and engineering drawing. PTC provides the following Creo Parametric tutorials that cover these techniques:

• Pre-requisite reading

• Alphabet Soup

• Creo Primer This tutorial builds on the techniques covered in the above tutorials.

http://www.f1inschools.com/



Downloading the tutorial files A zip containing the tutorials Creo files can be downloaded from http://www.ptc.com/company/community/schools/ then follow the link for Resources.

http://www.ptc.com/company/community/schools/



Procedure one – Setting up key dimensions Scenario: A Creo assembly has been created with axles, wheels, CO2 bottle and balsa blank in place. The model has annotations reporting critical dimensions.

• Body to track distance

• wheelbase

• wheel width (track)

• CO2 bottle above road

Blue dimensions can be used to change the model directly. Red dimensions report distances that report measurements from the model and will update when features in the model are changed. In this session, students will learn how to alter key dimensions to comply with the competition rules and model within the envelope of the balsa blank.



Step 1: Opening the assembly In this section you will set the working directory and open the car assembly.

1. Start Creo Parametric. 2. Set the working directory to the folder where the tutorial files are located. 3. Open file the file CREO_R_TYPE.ASM.

What have you learned?

• The need to set the working directory before every Creo modeling session.

• Navigating folders using the folder browser in Creo.

• How to open a Creo assembly.



Step 2: Changing key dimensions The blue dimensions will be changed to:

• Body to track distance = 6.5

• Wheelbase = 120 The model will then be regenerated to see the changes.

4. In the Model toolbar select the Annotate tab. 5. On the model, double click on the wheelbase dimension. 6. Type the new value 120 then press Enter on the keyboard.

7. In the Quick Access toolbar, click Regenerate or press Ctrl+G to update the model. You will see the wheels move to reflect the new wheelbase distance.

8. Make a note of the red dimension CO2 BOTTLE ABOVE ROAD. 9. Repeat the previous steps to change the Body to track Distance to 6.5.



Has the CO2 BOTTLE ABOVE ROAD distance changed? The position of the CO2 bottle hole in the block is fixed so when the balsa block was lowered closer to the track the CO2 bottle hole also moved closer to the track. Does the new value comply with the competition rules?

10. Save your work.

11. In the Graphics toolbar, open the Saved Views drop-down list and select TOP for the view

The Wheel width (vehicle track) distance is determined by the length of the axle so we will alter this and see the effect on the model.

12. In the model tree, expand the entries for WHEEL_SET.ASM and AXLE.PRT.

13. Right mouse click over Extrude 1 and, from the floating menu, select Edit.

14. Double click on the extrude length, type in the new value 75 then press Enter.



15. In the Quick Access toolbar, click

Regenerate or press Ctrl+G The wheels are now further apart and the annotation dimension is reporting the wider track.

16. In the quick access toolbar click Undo twice to revert to the original wheel width.


• That that Creo models can be controlled by top level dimensions and parameters in parts and assemblies.

• The benefits of top-down models allowing late changes to update the entire assembly.

• How to edit a Creo model to define key measurements that comply with F1 in School rules.



Procedure two – Concept design With the key dimensions decided, the designer now focusses on the shape of the car body. Freehand sketches are a critical means of recording and communicating ideas.

One or more of the early ideas would then be developed into detailed sketches. Here is a hand drawn perspective sketch.



These are orthographic views with a plan and side elevation. Notice how features in the two views align vertically.

The final sketches can are then used as a reference when modeling the design using Creo.

1. In preparation for modeling your own design research F1 car shapes and practice sketching your ideas. Always keep in mind the competition rules to avoid having to make late changes to your design.

2. Investigate how birds and fish cope with the aerodynamic and hydrodynamic problems of travelling through fluids.

3. Research designs for racing yachts and aircraft looking for ideas.


• That hand sketches are very useful for recording and communicating ideas to others.

• Awareness of drawing conventions including pictorial, isometric, perspective and orthographic plus major views in orthographic drawings are aligned vertically and horizontally.

• The importance of constraints (F1 in Schools rules) when designing.



Procedure three – Modeling the body with Creo Overview Here you will be shown how to use the 3D modeling tools in Creo Parametric to create a 3D model of the body shape. The Creo shape will reproduce very closely the design sketches. The balsa block will be machined to remove material so ‘subtractive’ modeling techniques will be used in Creo. As a reference:

• A “subtractive” modeling approach typically starts with a block and removes/subtracts material from this block to achieve the required shape.

• An “additive” modeling approach typically starts with an empty part and ‘adds’ geometry to achieve the required shape.

For symmetrical shapes like car bodies, it’s good practice to model half the shape and at the last moment, mirror the actions to create an identical other half.

Before mirror After mirror



Step 1: preparing the model Overview The balsa blank with be activated and new features inserted after the extrusion that creates the guide wire groove. After this step you will not see any difference in the assembly.

Step by step 1. In the Graphics toolbar, turn off the

display of Annotations . 2. In the ribbon, click the Model tab to

activate it. 3. From the Model tree, right-click

BALSA_BLANK.PRT and from the floating menu, select Activate.

4. In the model tree, expand BALSA_BLANK.PRT to see the feature list.

5. With mouse cursor over the entry for GUIDE_WIRE_BROOVE, right click and, from the floating menu, select INSERT HERE.

You are now ready to start removing material from the balsa blank to create the car shape.




• Changing the way a Creo model appears on the screen.

• Activating a part within a Creo assembly.

• Selecting geometry in a Creo model.

• Inserting new features in a model tree.



Step 2: Car body profile Overview This feature will form the initial profile of the car. An extrusion will be created with an internal sketch located on the MID_PLANE datum. Extrusions require a sketch to define the shape so are called ‘sketch based’ features or ‘shapes’. The extrusion you will create here removes material, intersecting all surfaces as shown on the right. The finished sketch is shown below.



Step by step

1. In the Model tab, select Extrude . 2. Expand BALSA_BLANK.PRT and select the MID_PLANE datum. Don’t worry

that the MID_PLANE datumn is grayed out.

3. In the Graphics toolbar click Orient to view the sketch plane parallel to the screen.

4. From the Setup toolbar, select References , and left click at each point L1-L2 to create references from the geometry. L3 references the top of the hole in the block for the CO2 cartridge.

5. In the References dialog, click Close to finish creating references.

6. From the Sketching toolbar, select Line Chain and follow the steps below. 7. Draw a vertical line between L1 and L2 and then change the vertical dimension to

31 mm.

8. Add a horizontal line starting at the top L3 of previous line and finishing at L4. For the moment, leave the measurement as it is, we will change it later.

9. Add another horizontal line along the bottom of the block starting at the front corner



L5 and stopping just short of the rear face at L6. Make sure the line is long enough to pass beyond the rear wheel.



10. Draw another straight, diagonal line from the end of the line L7 to the top edge of the balsa blank L8. Make sure this line is not constrianed to any other geometry. For the moment the dimensions are not important.

11. From the Dimension toolbar, select Normal Dimension . 12. Left-click at L1 then left-click at L2. Middle-click at M3 to locate the dimension text. 13. Change the dimension to 50.

14. With Normal Dimension still active, add an angle dimension as shown here.

15. Change the angle dimension to 30.



16. In the Sketch ribbon, Sketching group select Fillet .

17. Select the horizontal line L1 and the vertical reference at L2.

18. Activate the One by One tool, lasso the T constraint at L3 and delete it.

19. Change the vertical

dimension to 6 mm. 20. Use the Normal Dimension

tool to create a horizontal dimension L1 – L2

21. Change the value to 15 mm

22. Draw a horizontal line from

the diagonal L3 to the top corner of the block L4.

23. In the Sketch ribbon, Sketching group, select Fillet .

24. Select the horizontal line at L5 and the vertical reference at L6.



25. Activate the One by One tool, lasso the T constraint at L7 and delete it.

26. Using the Normal Dimension tool create a dimension

L1 – L2.

27. Use the One by One tool change the value to 10 mm.

28. If necessary click on the arc at L3 and middle click at M4 to create a radius dimension constraint.

29. Us the One by One tool to change the radius of the arc to 100 mm.

30. Use the Line Chain tool to

add a vertical line between L1 and L2 connecting the two arcs.

Notice the sketch is now shaded showing it is a valid shape for extrusion.

31. Select OK to complete the sketch and return to the Extrude ribbon.

32. Change the view to Isometric.



33. From the Extrude Dashboard, depth

drop-down menu, select Extrude to intersect with all surfaces , then select Remove Material .

34. Make sure the pink arrows are orienteed as shown here.

35. Select OK to complete the extrude and add it to the model tree.

36. Save your model.


• Changing the way a model is viewed on screen.

• Extrusions require a sketch to define the shape.

• Extrusions are called ‘sketch based’ features and found in the ‘shapes’ group in PTC Creo.

• Using sketching tools including: Select One by One, Line Chain, Fillet, Delete Line Segment.

• That a closed profile sketch is required for extruding a solid.

• Referencing existing geometry in a sketch and managing geometric references

• Managing dimension constraints in a sketch.

• Defining an extrusion.



Step 3: Nose side profile Overview This feature will create the side profile for the nose of the car. The sketch will be located on the MID_PLANE datum, removing material intersecting all surfaces. Below is the finished sketch you will create in the next section.

Step by step 1. Make sure BALSA_BLANK.PRT is

still activated in the model tree.

2. Start an Extrude and, in the model tree, select the MID_PLANE datum for the profile sketch.

3. Orient the sketching plane parallel to the screen .

4. From the Sketcher ribbon, Setup group, select References then add references in the positions L1 – L3 shown below .



5. Use the 3 Point Tangent end Arc tool, select the start L1 and end point L2 then move the mouse until a tangent constraint is showing at L1 then click at L3.

6. If a tangent is not created automatically, in the Constraint group, use the Tangent tool to add one manually.

7. Change the arc radius to 120 and the

vertical dimension for the endpoint to 12.

8. If the bottom end of the curve drops below the bottom of the body, use the selct tool to select it, then drag it up. (or type -12 as dimension).

9. Add the diagonal straight line shown

here and dimension the angle to 45 degrees.

10. Add a dimension from the nose to the back of the block and change it to 190mm.

The extrude you are creating to remove material would work but, to avoid a problem mirroring this feature later, we need to make this sketch enclosed.



11. Draw lines between points L1, L2, L3 and L4.

The shaded area shows the sketch is enclosed and should extrude successfully.

12. Click OK to complete the sketch and return to the extrude ribbon. 13. In the extrude ribbon, change the

depth setting to intersect with all surfaces .

14. Select Remove Material . 15. Make sure the pink arrows are pointing

in the directions shown.

16. Preview the feature then, click OK to complete the extrusion.




Step 4: Reduce cockpit width Overview This step will project the cockpit profile and use an extrusion to reduce its width. The sketch will be located on the MID_PLANE datum, and be extruded to remove material from the side face of the block to a point 13mm from the MID_PLANE.

Step by Step 1. Make sure BALSA_BLANK.PRT is activated.

2. Start Extrude and select the MID_PLANE datum as the sketch plane.

3. Orient the sketching plane parallel to the screen . 4. In the Sketch ribbon, Sketching group,

select Project . 5. Click at each of the points L1, L2, L3

and L4 to project these edges from the model into the sketch.



6. Draw a Line Chain horizonal from L1 to L2

7. Draw a 3-Point / Tangent End Arc from L2 to L3.

8. Strart the Line Chain tool and closk at L3 to start the line.

9. Move the mouse along the vertical line at near L4 until you see a Tangent T constraint at L3.

10. Click at L4 to create the line. Be careful not to snap L4 to the mid point of the vertical line.

11. Use the Delete Line Segment tool to trim the lower part of the projected line at L1.

12. Activate the One by One tool. Your sketch should shade in as shown below showing it will extrude successfully.

13. Add and/or change

dimensions to those shown here.

14. Click OK to close the sketcher and return to the extrude ribbon.



15. Change to a Trimetric view. 16. In the Extrude ribbon, change the

depth to 13. 17. Check in the Extrude dashboard and,

if necessary, select the Remove Material button.

18. Open the Options drop down tab and under Side 2, choose To Selected.

19. Select the side of the balsa block at L1

The Extrude changes back to add material automatically.

20. Preview the feature then click OK to complete the Extrude.







• Using sketching tools including: Project, Select One by One, Line Chain, 3 Point Tangent Arc, Delete Line Segment.

• That a closed profile sketch is required for extruding a solid that will be mirrored later.



• The sketch for an extrusion does not have to be at the location where material is added or removed.



Step 5: Rear wheel cutout Overview This section will show you how to create the cutouts to accommodate the rear wheels. The sketch will be located on the bottom of the balsa block and extrude upwards removing material to intersect all surfaces.

1. In the assembly, make sure BALSA_BLANK.PRT is activated.

2. In the Model ribbon, Shapes group, click Extrude and select the bottom surface of the balsa block for sketching.

3. Orient the sketching plane parallel to the screen . 4. From the Sketcher ribbon, Setup

group, select References , create new references L1 and L2 on the edges of the block, then select the Close button.



5. Draw a Corner Rectangle snapped to the corner of the block at L1 and surrounding the wheel to L2.

6. Change the dimensions to those

shown on the right.

7. In the Sketcher ribbon click OK to close the sketch.

8. Change the view to Trimetric.

9. In the Extrude ribbon,make sure the Remove Material button is selected.

10. Make sure the pink direction arrows are in the direction shown here.

11. Change the depth setting to intersect with all surfaces .

12. Preview the feature and then, click OK to complete the extrusion.




Your model should now look like this.



• Referencing existing geometry in a sketch.

• Using sketching tools including: Corner Rectangle.

• That a closed profile sketch is required for extruding a solid.





Step 6: Front wheel cutout Overview This section will show you how to create the cutouts to accommodate the front wheels. The sketch will be located on the bottom of the balsa block and extrude removing material upwards to intersect all surfaces. Below is the sketch you will be shown how to draw in the next section.

1. In the assembly, make sure BALSA_BLANK.PRT is activated.

2. In the Model ribbon, Shapes group, click Extrude and select the bottom surface of the balsa block for sketching.

3. Orient the sketching plane parallel to the screen . 4. From the Sketcher ribbon, Setup

group, select References , create new references L1 and L2 on the edges of the block.

A reference should already exist along the center line of the body. 5. If there isn’t a reference there, click at

L3 to create one. 6. Close the References dailog.



7. Use the Line Chain tool to draw the shape L1 – L4 surrounding the wheel.

8. In the Sketcher ribbon, Sketching

group, use centerline to create a horizontal centerline L5 – L6 snapped to the reference.

9. Add or change the 75 mm and 45

degree dimensions shown on the right. You will now create a dimension showing the final width of the nose. This uses a technique of left/right clicks based on the centerline.

10. Select the Normal dimension tool. 11. Left click on the geometry at L1 – L2 -

L3 then middle click at M4 to locate the dimension text.

12. Change the dimension value to 39.


14. Change to Trimetric view.

15. If necessary change the extrude

direction to upwards. 16. In the Extrude ribbon, select Remove

Material . 17. Change the depth setting to intersect

with all surfaces . 18. Make sure the pink arrows are pointing

in the directions shown here.

19. Click OK to complete the extrusion.




Your model should now look like this.




• Using sketching tools including: Line Chain, Centerline.






Step 7: Nose shape Overview This section changes the plan shape of the nose. The sketch will be located on the bottom of the balsa block and extrude removing material to intersect all surfaces. Below is the finished sketch you will be shown how to draw in the next section.

Step by step 1. Make sure BALSA_BLANK.PRT is activated.

2. Start an Extrude and select the bottom surface of the balsa block for the sketch plane.

3. Orient the sketching plane parallel to the screen . 4. In the Sketcher ribbon, Setup group,

select References . 5. Click on edges L1 and L2 to create

references then select Close.



6. Use Line Chain to draw two

straight, connected lines L1, L2 and L3, making sure you don’t create a Mid Point constraint at L3.

7. Use the three point Arc tool and click L1 for the start point.

8. Click at L2 for the end point then, move the mouse to alter the radius of the arc until you see a Tangent T symbol at the end nearest the wheel (L2). When you see the symbol, left click at L3 to finish creating the arc.

9. In the Sketch ribbon, Sketching group, select Centerline and then draw a centerline snapped to points L4, L5 along the reference line at the center of the block.

10. Select the Normal dimension tool. 11. Left click on the geometry at L1, L2

and L3 then middle click at M4 to locate the dimension text.

12. Change the dimensions to the values shown here.





15. In the Extrude ribbon, change the

depth option to intersect with all surfaces

16. Select Remove Material . Make sure the pink arrows are in the correct direction.

17. Click OK to complete the extrude.





• Using sketching tools including: Line Chain, 3 Point Tangent Arc, Centerline.

• Managing geometric constraints in a Creo sketch.






Step 8: Shape the side pod Overview This section changes the plan shape of the side pod. The sketch will be located on the MID_PLANE. Below is the finished sketch you will be shown how to draw in this section.


2. Start an Extrude and select MID_PLANE for the sketch plane.

3. Orient the sketching plane parallel to the screen . 4. In the Sketcher ribbon, Setup group,

select References . 5. Create references at the front L1 and

top L2 of the side pod then click Close in the dialog to finish creating references.

6. Use Line Chain to draw two

straight, connected lines L1, L2, L3, making sure you don’t create a Mid Point constraint at L3.



7. Use the Three Point Tangent Arc tool and click L1 for the start point. Click at L2 for the end point then, move the mouse to alter the radius of the arc until you see a Tangent T symbol at the end nearest the wheel. When you see the symbol, left click L3 to finish creating the arc.

8. Change the dimensions to the values

shown here. 9. Change the view to Trimetric.


Don’t worry if the extrude switches to Remove Material. 11. In the Extrude ribbon, change the

depth option to …to selected… . 12. Select the flat side of the nose at L1.

13. In the Extrdue ribbon, open the

Options drop down tab and under Side 2, choose To Selected.

14. Select the side of the balsa block at L1

15. Click OK to complete the Extrude.







• Using sketching tools including: Line Chain, 3 Point Tangent Arc.






Step 9: Round the cockpit edges Overview In this section you will round the cockpit edge. Rounds do not require a sketch so are referred to as a ‘direct’ or an ‘engineering’ feature. Rounds will follow edges connected tangentially. A single edge will be selected for a 13 mm round.


activated.

2. Apply a 13 mm Round to the edge L1.

3. Click OK to complete the Extrude.

4. Save your model.




• Rounds are referred to as a ‘direct’ feature as they do not require a sketch.

• Rounds are applied to existing geometry.

• How to use a round feature applied to selected edges on a Creo model.

• Changing the radius of a round feature.



Step 10: Adding further rounds Overview Rounds of 3mm radius will be added to blend parts of the body together.


activated.

2. Apply a 3 mm Round between the cockpit and the main car body.

3. Click OK to complete the round.

4. Add a new 3 mm Round between the side pod and the main car body.


6. Save your model.




• Rounds are referred to as a ‘direct’ feature as they don’t require a sketch.

• Rounds are applied to existing geometry.

• How to use a round feature applied to selected edges on a Creo model.

• Changing the radius of a round feature.



Step 11: Rear wing Overview The competition rules allow aerodynamic surfaces at the front and rear of the car. This section shows how to add an airfoil wing at the rear of the car.

The airfoil shape will be sketched on the MID_PLANE and extruded, adding material for a distance of 30 mm. The sketch you will create is shown below.


2. Begin an Extrude and select the MID_PLANE datum as the sketch plane.

3. Orient the sketching plane parallel to the screen .

4. In the sketcher ribbon, Sketching group use the Centerline tool to create a horizontal consuction line.

5. Dimension the height of the line 40 mm from the bottom of the balsa block.



6. Create one large and one small

Center and Point Circle snapped to the centerline.

7. Dimension the circles 4 mm and 1 mm diameter.

8. Use the Line Tangent tool to join the tops and bottoms of the circles.

9. Use the Delete Line Segment tool to trim the sketch forming an airfoil outline.

10. Add dimensions to set the length of

the airfoil to 25 mm and 3 mm for the position from the rear of the balsa block.



11. Click OK to complete the sketch. 12. Change the extrusion length to 30

mm and click OK to complete the extrusion.

13. Change to a Trimetric.

14. Where the rear wing intersects the

body shape, add a 3 mm radius

Round . Notice how the round will follow all edges that are connected tangentially.






• Using sketching tools including: Centerline, Center and Point Circle, Line Tangent, Delete Line Segment.




• The sketch for an extrusion does not have to be located where material is added or removed.

• Applying a round and defining the radius

• That rounds follow all edges connected tangentially.



Step 12: Mounting for front wing Overview The front wings are separate parts bonded into holes either side of the nose of the balsa body. This section will show you how to create the obround holes in the body.

Note: Obround refers to a shape made up of two semicircles connected by parallel lines. It is used extensively in engineering, particularly in the sheet metal industry.

The hole shape will be sketched on the MID_PLANE and extruded, removing material and intersecting all surfaces.

Step by Step 1. Make sure BALSA_BLANK.PRT is activated.

2. Begin an Extrude and select the MID_PLANE datum as the sketch plane.

3. Orient the sketching plane parallel to the screen . 4. Draw two equal radius Center and

Point Circles with their centers aligned horizontally.

5. Join the circles across top and bottom with Line Tangent .



6. Use the Delete Line Segment tool to trim the lines leaving only the outline.

7. Change/add the dimensions shown here.

8. The 178 mm dimension is to the back of the block.


10. Click OK to close the sketch.

11. In the Extrude ribbon, change the

depth to Intersect with all surfaces , in the direction shown and with

Remove material .



The half body is now finished.





• The term obround referring to a shape made up of two semicircles connected by parallel lines.








Step 13: Mirror the body shape Overview The final step when creating the body is mirroring all the features that create the half body shape. The features highlighted here will be mirrored. Features have been renamed to make it clearer what each one does. Rename features by right clicking and, from the floating menu, select Rename. It’s good practice to name features to help communicate your designs to others and when returning to edit a model.

1. In the model tree, make sure

BALSA_BLANK.PRT is activated. 2. Expand the model tree to show the

feature list. 3. Select the extrusion below the

GUIDE_WIRE_GROOVE. 4. Hold down SHIFT and click to select

the last feature before the Insert Here flag.

5. In the Model ribbon, Editing group, select Mirror .

You will be prompted to select the mirror plane. 6. In the model tree, select the

MID_PLANE.

7. In the Mirror ribbon, click OK to complete the mirror feature.

8. Activate the top level of the assembly and Save your model.

The car body is now finished and shown here without the assembly.

These features will be

mirrored




• Features can be inserted into an existing model tree.

• Features can be renamed.

• Features can be mirrored.

• The mirror feature requires a flat plane reference.



Procedure four – Creating the front wings Overview The competition rules specify the front wing should be a separate part of the car. To comply with this rule the front wings were designed to be rapid prototyped from ABS plastic using the Fused Deposition Modeling (FDM) process.

Step 1: Modeling the Airfoil Overview A new part is created in the context of the assembly, constrained at the default location. The airfoil shape will be extruded from a sketch on the RIGHT datum plane. The first direction for the extrusion is 35mm and the second direction is the side face of the nose.

The sketch for the airfoil is shown here. The 183 mm dimension is to the rear face of the balsa block.



1. ACTIVATE CREO_R_TYPE.ASM 2. In the Model ribbon, Component toolbar,

select Create . 3. In the Component Create dialog,

change the name to WING_FRONT_LEFT and make sure type is Part and subtype is Solid.

4. Click OK to close the dialog.

5. In the Creation Options dialog, accept

the defaults of Copy from Existing for Creation Method and solid_start_part_mmks.prt for the Copy from… option.

6. Click OK to create the part.

7. Click anywhere in the graphics window to temporarily locate the new part. 8. In the Assembly ribbon, Automatic drop-down list, select Default for the part

placement.

9. In the Assembly ribbon click OK to place the component. 10. In the model tree, Activate WING_FRONT_LEFT.PRT then, expand the model tree

for that part. 11. Start a new Extrude and, from the

model tree, select the RIGHT datum plane L1 as the sketch plane.

12. Orient the sketching plane parallel to the

screen .



13. In the Sketcher ribbon, Setup group

click on References . 14. Create a reference from the front

semicircle at L1.

15. In the Sketcher ribbon, sketching group,

draw a Centerline at an angle through the center of the reference.

16. Dimension the angle to 12 degrees.

17. Select Center & Point Circle tool and draw two circles, one smaller than the other and attatched only to the center line. The dimensions are not important for now.

18. Use Line Tangent to connect the tops and bottoms of the two circles.

19. Use Delete Line Segment to trim those parts of the circles not needed to form an airfoil shape.



20. Add/alter dimensions to those shown

here.

21. Click OK to complete the sketch. 22. Switch to Trimetric view.

23. The Side 1 extrusion depth should be set to 35 mm.

24. The Side 2 direction should be To Selected and click on the side face L1 of the nose.

25. Click OK to complete the extrusion.

26. Save your work. You may get a message that the model is not regenerated, ignore that for now.

The front wing should look like this.





• Creating a new component in the context of an assembly located using a default constraint.





• The sketch for an extrusion does not have to be located inside the material that is added or removed by the feature.



Step 2: Create the mounting peg Overview A peg will now be created to fit into the hole in the nose of the body. An extrude will be used linked to a new sketch on the MID_PLANE datum. The sketch outline will be projected from the hole in the nose to ensure a perfect fit.

Step by step 1. Make sure WING_FRONT_LEFT.PRT is

activated.

2. Start an Extrude and select the RIGHT datum as the sketch plane.

3. In the Sketch ribbon, Sketching group,

select the Project tool. 4. Click on the edges of the obround hole in

the body to project lines into the sketch. Make sure you only click once on each edge to avoid creating duplicate lines.

5. Click OK to close the sketch.

6. Switch to Trimetric view. 7. In the Extrude ribbon, change the depth

setting to 6 mm. 8. Open the Options drop-down menu and

change the Side 2 option to To Selected .

9. Select the side surface L1 of the nose.







• Using sketching tools including: Project.


• Defining an extrusion up to a selected surface.



Step 3: Add a wing endplate Overview Race car designers use a great many aerodynamic techniques to improve performance. Endplates is a method of stopping air spilling off the end of a wing.

The endplate is a simple extrude from a sketch located on the end surface of the wing. You do not have to copy our shape of end plate, you can create a design of your own.

Step by Step 1. Make sure WING_FRONT_LEFT.PRT is activated.

2. Start an Extrude and select the end face of the wing as the sketch plane.

3. Sketch a shape for the end plate. You do not have to follow this shape as long as it is a single, unbroken outline.

4. Click OK to close the sketch. 5. Change the Extrude depth to 1 mm.

6. Click OK to close the extrude.





• Using sketching tools learned previously.


• Defining an extrusion to a specified depth.



Step 4: Add rounds Overview Rounding the sharp corners on the wing will help with manufacture and make the wing more user-friendly. Adding rounds on the narrow edges will make the wing more aerodynamic.

Step by step

1. Select Round . 2. Hold down CTRL and select the short

edges across your wing endplate. 3. Change the radius to 3 mm or a suitable

value.


5. Start another Round and, holding down

CTRL, select the thin edges around the endplate.

6. In the Round ribbon, open the Sets tab and select Full Round.


8. Save your work. The finished wing will need to be mirrored to make a wing for the right side of the car.





• Using previous experience to add rounds to selected edges.



Step 5: Creating a new mirrored part Overview Creo provides tools to create a new part mirrored from an existing model. In the car assembly, a new part will be created in context, mirroring the existing FRONT_WING.

Step by Step 1. Make sure the top assembly,

CREO_R_TYPE.ASM is activated. 2. In the Model ribbon, Component group,

select Create to start a new component in the assembly.

3. In the Sub-type list select Mirror radio button.

4. Type in a name for the new part. Here we have used wing_front_right.

5. Click OK.

The Mirror Part dialog will open. 6. In the model tree select

WING_FRONT_LEFT.PRT as the Part Reference.

7. In the model tree select the VERTICAL_REFERENCE datum as the Planar Reference.

8. IN the Mirror part dialog, click to preview the new part.

9. Click OK to finish creating the new part.




• New parts can be created in assemblies

• A new part can be a copy of an existing part in an assembly.

• The copied part in an assembly can be a mirrored version of the original.

• New parts can be Mirrored copies of existing parts can be created in an assembly.

• A flat datum/surface is needed to act as a mirror plane for a mirrored copy.



Procedure five – Part properties Step 1: Apply a material definition to the wings Overview Any measurement or physical simulation that relies on the mass of a part will be affected by the material properties. New parts do not have a material defined so we will apply an ABS material definition to the front wings. There will be no visible evidence material properties have been applied but the mass, density and physical properties of the part will now be accurate as if it were made from ABS plastic.

To demonstrate the changes you will carry out a mass analysis before and after applying new material properties. Step by step 1. Right click on the first front wing

and, from the floating menu, select Open.

2. Activate the Analysis ribbon and from the Model Report group, click Mass Properties .

The mass properties dialog opens. 3. In the dialog click on to carry

out the analysis. The results window will display a lot of data about your model including its MASS. In this example the mass is being reported as 2.06 x !03 kg or 2,060 kg! Does 2 metric tons sound right for this small plastic part? The default density used by Creo is very high to warn the user they have not applied material properties to the part. There is little chance the lack of material properties would go unnoticed.

4. Click to close the Mass Properties dialog.



5. Open the File menu, select Prepare then Model Properties . 6. In the Model Properties dialog, next to the Material entry, click Change. 7. In the Materials dialog, select L1 the plastic_abs.mtl file.

8. Click L2 to transfer the material definition to the model. If you are prompted to change the materials units to that of the model, click Yes.

9. Click OK to close the Materials dialog. If you see a message window about converting units, click Yes.

10. Close the Model Properties dialog. 11. Save the model and Close it to return to the assembly.. 12. Repeat this section applying ABS properties to the other front wing.



13. Carry out another Mass

Properties analysis on a wing. This time the results window reports a mass of 2.16 x !0-3 kg or 0.00216 kg or 2.16 grams Compare this with the mass of 2 metric tons before a material property was assigned! Does just over 2 grams sound like a more realistic value for an ABS plastic wing little bigger than a postage stamp?

14. Click to close the Mass Properties dialog.


• PTC Creo has comprehensive analysis tools

• How to carry out a mass analysis on a Creo model

• Applying material properties to a Creo model.



Step 2: applying an appearance Overview To change the look of a model we apply an appearance or texture to surfaces. Creo has a large appearance library including a wide range of plastics. Here are some examples of textures available in Creo.

Default Injected plastic Carbon fiber

From the examples here, an injected plastic appearance will be used in the worked example that follows.



Step by step 1. Open the FRONT_WING_LEFT.PRT. 2. Select either View or Render tab to se

the Appearances Gallery . 3. Open the Appearance Gallery drop-down

list L1. 4. Expand the library section L2 and, select

L3 adv-plastics-injected.dmt. 5. The Library section will now display the

injected plastic appearances.

6. Select one of the appearances L4, here we have selected red injected plastic

.

Although you can select individual surfaces to apply the texture (hold down CTRL for multiple surfaces), selecting the part name at the top of the model tree applies the appearance to the entire model. 7. At the top of the model tree, click on the

part name then right click to finish applying the texture.

8. The model should change to the new

color.

9. Save your model. 10. Open the other wing and apply the same

appearance.




• PTC Creo has libraries containing an extensive range of appearances that can be applied to models.

• How to find select and apply appearances to a model.

• Appearances can be applied to individual surfaces or the entire model.



Step 3: Editing parameters Overview Each part has a number of parameters associated with it including the material it will be made from, the project it belongs to and who modeled it.

In the section that follows you will update the parameters for the wing parts. Step by step 1. Open one of the front wings.

2. In the Tools tab, Model Intent group, click on Parameters. The Parameters dialog opens. 3. Click in each of the cells in the Value column and type in your information. There is

no need to change the material value, Creo has updated this for you.

4. Save your model.

5. Repeat this process to add parameters to the other front wing.




• PTC Creo models have properties associated with them including text and material properties.

• How to edit the properties of a Creo part.



Procedure six – Mass analysis Success in the F1 in Schools competition is all about acceleration. One of the formulas used to calculate acceleration is:

F=Ma Re-arranged we get: a = F/M

The CO2 bottles and piercing mechanism are supplied by the organizers so it is almost impossible to alter the force (F) propelling the car. We can alter the mass (M) of the car and, because this is on the bottom of the formula, the smaller the mass the faster the car will accelerate. So mass reduction is one of the key factors for success. The competition rules specify a minimum mass for the car without CO2 bottle of 55 grams (2013 rules). Designing a car as close to this minimum mass will go a long way to creating a fast car. You have already carried out mass analysis using Creo. Applied to the car assembly, this will guide you to achieving a target mass before you manufacture the body.



Task 1: Mass properties analysis Overview A mass properties analysis in Creo will establish the total mass of the car. You will make changes to the body, reducing the material before carrying out another mass analysis. Step by step 1. The finished car assembly should

be open on screen. 2. Carry out a mass properties

analysis and record the result. 3. For the tutorial car: Mass = 84 grams

4. In the model tree, activate the body of your car and expand it to see all the features.

5. Edit the sketch for the extrusion that creates the initial profile. Reduce the height of the main body from 31 to 28 mm.

6. Regenerate the model.

15. Carry out another mass properties

analysis and record the result. 16. For the modified car: Mass = 78.4 grams

Clearly there are plenty of opportunities to remove material from the body without going under the minimum weight rule. A powerful feature in Creo called Behavioral Modeling Extension (BMX), will optimize a design based on chosen criteria. The user identifies a goal, in this case mass, and chooses variables in the model to alter, for example, the vertical thickness of the car body. Creo does iterative alterations and regeneration of the model to achieve the desired goal.



To learn more about Behavioral Modeling Extension (BMX), log in to PTC’s Precision LMS online learning for schools: https://plms4schools.ptc.com/


• Understand some of the factors that contribute to a fast racing car.

• The relationship between the thrust (force) from the CO2 bottle, the mass of the car and how fast it will accelerate.

• Analysis tools in Creo include Mass Properties.

• How to perform a Mass Properties analysis in Creo.

• Activating a part in a Creo assembly.

• Editing features in an existing Creo model.

• A Creo model regenerates automatically after changes are made to features.

• That Creo can optimize designs by performing iterative changes to achieve a goal parameter.

• PTC provides teachers and pupils with free access to Precision LMS online multi-media tutorials for Creo and other PTC software.

https://plms4schools.ptc.com/



Procedure seven: Material density. Step 1: properties of the balsa blank Overview Balsa is a natural material so its properties vary including strength, density and mass. You already know that F1 in schools rules set a minimum weight limit for the car. To get the most accurate analysis we need to know the exact density for the balsa block you will use.

http://www.kingstongardenclub.com/amazon_river.htm

Step by step The first step is to work out the volume of the balsa block. Balsa block 22.3 mm long, 65 mm wide, 50 mm tall The volume of a cuboid is L x W x H So: 223 x 65 x 50 = 724,750 mm3

Guide wire groove 6 x 6 x 223 = 8,028 mm3 (volume).

CO2 bottle hole 0.95 radius x 5.2 depth. Volume = π r2 x length 3.142 x 09.5 x 09.5 x 52 = 14,745 mm3

50

65

2230

2230

6 x 6

52 19

http://www.kingstongardenclub.com/amazon_river.htm



Block Volume The volume of the block can now be calculated. 724,750 - 8,028 - 14,745 = 701,977 mm3

Compare the volume calculated manually with a ‘mass properties’ analysis of the Creo model. 1. Open the Creo model of the original

balsa block.

2. Activate the Analysis ribbon and from

the Model Report group, click Mass Properties .

The mass properties dialog opens. 3. In the dialog click on to carry out

the analysis. At the top of the results window you will see the volume of the model reported. 7.0197851 x 105 mm3 Or 701,979 mm3 There is a 0,0003 % difference between the two values. Can you suggest why they are not the same?

Click OK to close the Mass Properties dialog.

4. Weigh the actual block of balsa you

will be using to make your car body. Mass = 150 grams

Knowing the volume and mass of the block we can now calculate the density of that piece of balsa.



Density of balsa block Density of a material is defined as the mass per unit volume and expressed as kg/cm3 or g/cm3. Convert the volume from mm3 to cm3. 701,979 mm3 = 702 cm3 The Greek symbol ρ (rho) is used to represent density so: ρ = mass/volume Substituting the values we find: ρ (balsa) = 150 = 0.214 g/cm3 702

Creo density for balsa Let’s find the density value used in the Creo balsa material definition. 5. BALSA_BLANK.PRT should be open in

Creo. 6. Open the File menu, select Prepare and

then click on Model Properties. 7. In the Model Properties dialog next to the

materials sub-heading click on Change. 8. In the Materials dialog, right click over the

file wood_balsa.mtl and, from the floating menu, select Properties.

9. In the Material definition dialog L1 change the units to g/cm^3.

10. If you see a dialog about Changing Parameter units click OK.

11. From the Density field, note down the value.

ρ (wood_balsa) = 0.16 g/cm3.

Clearly the actual balsa block we weighed is denser than the default setting in Creo. To make the Creo model accurately predict the mass of the finished body design we will change the balsa density setting in Creo to match the density of the actual balsa block.



The Material Definition dialog should still be open. 12. In the Density field, enter the new value

of 0.214 and click OK. 13. If you are prompted a Young’s Modulus,

is required enter the value 5 GPa. 14. Click Save to Library and then click OK

to save the new balsa material definition to the Working Directory.

15. Close all dialogs.

Apply the new balsa material definition to the model 16. With BALSA_BLANK.PRT open in Creo. 17. Open the File menu, select Prepare and

then click on Model Properties. 18. In the Materials in the Model list, right

click on the material and from the floating menu select Delete.

19. Click OK to close the dialog.

20. In the Model Properties folder list, select Working Directory then click to select the new wood_balsa.dmt file.

21. Click to transfer the material to the model.

22. Right click over the file wood_balsa.mtl and, from the floating menu, select Properties. You should see the new value of 0.214 g/cm^3 for the density.

23. Cancel the Material Definition dialog and close all other dialogs.




Check the new mass of the block 25. Activate the Analysis ribbon and from

the Model Report group, click Mass Properties .

The mass properties dialog opens. Notice the dialog is also reporting the adjusted value for Density – 2.1400… 26. In the dialog click on to carry out the

analysis. Make a note of the mass reported for the model. Mass (balsa_blank) = 1.5022340e-01 KG. Mass (balsa_blank) = 150 grams. The uncut block now represents the actual mass of that particular balsa block. A body shape cut from that block of balsa will have a mass almost exactly the mass reported by a mass properties analysis in Creo.




• Balsa wood is a natural material whose properties vary.

• An awareness of density ρ (rho) and how it relates to materials.

• The properties of a Creo model can be altered to reflect the density of an actual piece of material.

• How to measure the key features of a balsa blank

• How to use mathematics to find the volume of a balsa block from the measurements.

• Compare the calculated volume with a Creo analysis.

• Suggest why a calculated value is slightly different from a Creo analysis.

• How to weigh a balsa blank.

• How to use mathematics to work out the density of a balsa blank.

• Compare the calculated value for density and a Creo analysis.

• How to alter the material properties for a Creo model to match the value for an actual balsa blank.



Procedure eight – CNC manufacture your car body There are major benefits of Computer Aided Design (CAD) in the downstream applications that use the solid model. One of these is Computer Aided Manufacture (CAM). The link between CAD and CAM involves interpretation of the external surfaces and the generation of instructions to drive the machine tool. The instructions are commonly called Computer Numerical Control (CNC) or G Code.

Creo STL Post processing CNC machining

The Academic Edition of Creo, supplied free to high schools, includes full CAM capability and there are significant benefits in using this which are descibed later in this document. Nearly all schools use STereoLithography (STL) files to transfer designs into the post-processing software supplied with their CNC machine tools so this technique will be demonstrated here.

http://images.google.co.uk/imgres?imgurl=http://www.boxford.co.uk/boxford/docs/products/productimg/cncrouter/A3hsrmi2.gif&imgrefurl=http://www.boxford.co.uk/boxford/docs/products/a3hsrmi2.htm&usg=__OM_nsXBu7JGExMlUnpUWf7Vob6c=&h=156&w=215&sz=16&hl=en&start=5&um=1&itbs=1&tbnid=5jle-0jsCdz48M:&tbnh=77&tbnw=106&prev=/images?q=boxford+router&um=1&hl=en&rlz=1I7ADSA_en&tbs=isch:1



Step 1: Exporting an STL file. Overview Step by step 1. Open the BALSA_BLANK.PRT. 2. Open the File menu, click Save As

then select Save a Copy…

3. In the Save As dialog, change the file

Type L1 to Stereolithography (*.stl) then click OK.

4. In the Export STL dialog, click Apply to see the mesh applied to the car body.

The STL process divides all surfaces of the model into tessellated triangles. Large flat surfaces require just a few triangles whereas tight, 3D curves require many more, small triangles. The values for Chord height and Angle control define how fine the mesh will be. If this scale of mesh was machined the flat surfaces would be visible on the surface of the balsa shape.



A finer mesh can be achieved by reducing the Chord Height. 5. In the Export STL dialog, change the Chord Height

to 0 (zero) and hit Enter then click Apply. An STL file will be created in the working directory.

Creo calculates the smallest practical chord height for this model. If this file was post processed and machined the STL triangles would not be visible.

6. Click OK to close the dialog and, Redraw the screen to remove the STL facets. Chord height - The maximum distance between a flat surface and the surface of the original model. Angle control - The maximum angle between adjacent facets.

The STL file that you saved can now be opened in the post-processor software you use with your CNC machine.

Chord height

Angle control




• Awareness of computer controlled manufacture.

• Sterolithography (STL) is a common file format for transferring CAD models to third party post processing software.

• How to export a Creo model as an STL file.

• The parameters that control the resolution of an STL file and how to specify them to achieve a desired outcome.

• Post processing takes a 3D shape and creates tool paths for the cutting tools to machine that shape.



Comparison of STL and Creo NC STL output to manufacture. The main problem of using STL files is they are not ‘associative’ which means any changes you make to the Creo model will not be recognized in the NC software controlling the machine. To update the machined shape you will need to export a new STL file and carry out post processing again.

Creo STL export Boxford 3D GeoCAM High speed router

Creo Complete Machining Included in the FREE Academic Edition for schools is Creo Complete Machining which is fully ‘associative’ with the Creo model. Any changes to the design are recognized and machine instructions updated automatically.

Creo part Creo Expert Machinist High speed router

One of the biggest problems in industry is making sure the most up-to-date design is manufactured. Once you commit to physical machining and manufacture, the implications of producing the wrong part can be very costly. An integrated and fully associative CAD/CAM process helps to ensure this doesn’t happen. In Creo Parametric the G-code is generated directly from the model produced in the design phase so, if the design changes, i.e. a hole is moved, the toolpath generated by the CAM module will be updated to incorporate this change.

Associative

Automatic

update

NOT Associative






• STL files are not associative so are not automatically updated when changes are made to the Creo model.

• The machining module in Creo is associative so any machining strategy is updated automatically when changes are made to the Creo model.

• Machine instructions use industry agreed ‘G’ codes.

f1 r type c2

Documents