2008 first robotics conference 3d design & practices presented by: bill samuels designer bae...

2008 FIRST Robotics Conference

3D Design & Practices

Presented by:Bill Samuels

Designer BAE Systems


45 minutes on these topics

• General Design Process• 3D Modeling Philosophies• Best Practices in Pro/ENGINEER• Tips and Tricks for Pro/Engineer• Web resources, Cool Links &

Acknowledgements


General Design Process

• Define the Task• White board• Documentation• Prototype• Peer Evaluation• Team Design Reviews• Build



Define the Task

Defining the task establishes a clear goal or goals.Do not confuse defining the task with a solution for the task.

An example: A pencil and a cup resting on a desk, the task is to get the pencil in the

cup. A solution would be placing the pencil in the cup using your hand. Using the expression placing the pencil in the cup limits the designer to

thinking that only the pencil is allowed to move.

Keep this list of goals and or tasks as generic as possible, this allows free thinking.



White board In conjunction with the discussion of defining the task, white boarding thoughts conveys information not easily expressed in words. This is also a great place to capture tasks that will assist in keeping the group focused.



DocumentationDuring the discussion and white boarding session it is very critical to document all information in an engineering notebook. This assures that data and progress will not be lost between sessions. A team scribe is recommended.



Prototype Once tasks have been defined and solutions considered, it is time to prototype the solutions. This can be done using pencil and paper, 2D & 3D CADD tools, and prototype/real world mockup.



Peer EvaluationA peer evaluation can be as simple as asking the person next to you to take a look at your design and give their thoughts. Peer evaluations should happen on a daily basis, this affords a second set of eyes a chance to capture design flaws and possible oversights.



Team Design ReviewsOnce the possible solutions have been captured and critically evaluated, it is time for a team design review. This review should explain the choices made and recommendations for the final design.



Build

Once the team has committed to a solution for the task it is time to build.

Once building has begun the team may find issues with some of the sub assembly designs. This will require going back and modifying some of the design concepts agreed upon in earlier design phases. This is when the design process would start over for that sub assembly, repeat as required until a complete solution is attained.

"Once you have a good idea (design), stay with it. Dog it. Work with it until its right!“

- Walt Disney


3D Modeling Philosophies

• Top Down Design• Bottom Up Design



Top Down Design

In top down design concept a top assembly envelope is cut into specific volumes. These volumes are assigned specific functions.

In this philosophy a specific sub assembly does not limit the top assembly’s progress. Nor does it require any specific sub assembly to be completed first.

This does require a lead designer to be responsible for maintaining volumes for sub assemblies and there locations and progression in the top assembly.



Bottom Up Design

In bottom up design concept sub assemblies are added as they are completed and no specific area is reserved for sub assemblies.

This requires a lead designer to be responsible for maintaining the top assembly and insure he has the latest data from each designer.



Choice of Philosophy

Both of these philosophies can work very well, as long as the entire team adopts the same philosophy. And just as important is that everyone on the team assists the lead designer in capturing the loose ends.

One of the biggest pit falls is trying to combine the two philosophies. And the biggest pitfall is not being proactive about resolving issues you aware of. If its not clear to you how a component works, ask. Not asking usually leads to lost work hours, over filing and a stressful environment.



Part modeling philosophy

Just as in an assembly a part can be top down or bottom up. In top down for a part you start with the smallest mass that will encompass the whole part and remove material to add definition.

In bottom up you start with a core shape and add features to complete the definition of the part.


Best Practices In Pro/ENGINEER• Always start with a plan• Create Features Individually• Create Features in a Logical Sequence• Carefully Create Parent/Child Relationships• Use Insert Mode• Use Layers• Guidelines for Good Sketcher Use• Checklist for Good Pro/Engineer Models• Guidelines for a Good Part Model• Guidelines for Good Drawing Creation


Best Practices In Pro/ENGINEER

Always start with a plan

It is very important to have at least a preliminary modeling plan or strategy in mind before modeling. This plan should include the design intent of the model. Since the plan will undoubtedly change as the project matures, it is not necessary to have this plan fully developed before beginning. It will be very easy to change the wrong plan into the right plan but be very difficult to change no plan into the right plan.



Create Features Individually

Do not create one feature that should be multiple features. This will allow any combination of features to be suppressed or deleted. Do not sketch multiple closed sections in sketcher. Each closed section should be a separate feature. For example: When creating a shaft with flanges and grooves, create the base shaft as one feature and each flange and groove as separate features. If the model is created as one feature, there is an “ all or nothing” scenario.



Create Features in a Logical Sequence

For Example: A cover may require 4 features to model correctly. If the cover is to have a lip around the top then the clearance holes for the fasteners that hold down the cover may have to come after the lip feature.



Carefully Create Parent/Child Relationships

Create only the Parent/Child relationships that are necessary for the model’s intent. Whenever creating a feature, always clearly identify the references used to constrain that feature. Whenever picking a reference, do so in a 3-D view. This practice will make it easier to identify exactly what is picked. Read the message window to validate picks, it lists what has been picked. A set of related features should be able to be suppressed and resumed without having to also suppress or resume unrelated features.



Use Insert Mode

Use Insert Mode before modifying or when adding features. Especially when working on a model with complex geometry or a large feature-count. By inserting close to the desired parent geometry, regenerating features that have no real bearing on the modification is avoided and the model regeneration time is reduced. When adding features, it will keep features in a logical order and keep parent/child relationships in check. After the modification or addition is done, resume the rest of the features.



Use Layers

Use default layers to automatically put various feature types on specified layers. To verify that these default layers are set for the part being worked on, either use the Layer menu in the Model Tree or verify the layer setup in the Config.pro file. The Layer menu will display the default layer options that have been activated. If any of the default layers listed is not activated, do so by editing the table. Create additional layers with logical names that describe the features assigned to it. They can assist in suppressing and resuming features. Keep in mind the top assembly has every layer of every part.



Guidelines for Good Sketcher Use• Use sketched centerlines and construction circles to achieve the

desired dimensioning scheme.• Do not allow any weak dimensions to remain in a completed sketch.

Either add constraints, convert the weak dims to strong or add strong dimensions to complete a sketch.

• As a rule of thumb, keep the number of dimensions in a sketch to a maximum of eight. Where more are needed to fully dimension a feature, create datum features first, then reference the datum features when in Sketcher. This technique will result in a robust model and minimize future difficulties with the Sketch. It also follows the “many simple features” rule to create models.

• Choose references sparingly. More references mean more feature to feature relationships that can make the model more difficult to work with as it progresses or changes. Choose only enough references to make the model follow the design intent.


Best Practices In Pro/ENGINEER • Choose references that won’t disappear. References like edges that

disappear when rounded or drafted, are not the best choice. Datums and planner surfaces are better. References from the base features are more stable than those of later features.

• When redefining a sketch, use Replace (Under Edit) rather than deleting a sketched entity whenever possible. Replace will give the new entity the same entity id number as the old entity. This will result in rerouting all the children of the old entity to the new. Note that even if you have not referenced a sketched entity someone else (working in Pro/ASSEMBLY, Pro/PIPPING, Pro/MANUFACTURE, etc.) might have a reference to that entity.



Checklist for Good Models• Does it use the standard configuration file?• Have the six standard views been created in the correct orientation.• Has an appropriate pictorial view for the drawing been created and

named for easy identification?• Were layers created as needed and correctly shown or blanked for the

drawing?• Are descriptive names for features assigned in the Model Tree where

possible?• Have similar features been compacted by using patters and groups?• Are Geometry Checks needed (is menu grayed-out)• Have the standard parameters been created and their values been

entered?• Have the standard relations been created?• Does it use the proper units systems (inch/lb/sec)?


Best Practices In Pro/ENGINEER• Has the correct density or material been assigned?• Has the correct file name been assigned?• Has the correct file location for storage, backup and retrieval been

validated?• Are assemblies using library fasteners whenever possible?• Have suppressed features been deleted?



Guidelines for a Good Part ModelThe goal is to create and name features so that any other

user can readily modify them at any time. Good modeling practices are far more important early in the modeling process than at the end as repair work.

Accomplish this by:• Following the standards in Pro/Engineer guidelines• Using the standard Start Parts when beginning a new

part• Consciously setting up your parent/child relationships• Creating a simple base feature • Creating simple sketches• Not sketching rounds or fillets when avoidable


Best Practices In Pro/ENGINEERGuidelines for Good Drawing Creation• Use the standard drawing set-up file• The model should regenerate without errors or geometry

checks prior to beginning the drawing• No erased views should be kept in drawings• Relate draft entities to objects or views, check for unattached

text ( missing leaders)• Make sure views do not overlap one another• Use only projected, detail, or auxiliary views whenever

possible (avoid multiple general views)• Check for line width and text size uniformity (as in standard

drawing set-up file)• Use shown dimensions as opposed to created dimensions

whenever possible• Delete all unused models from drawing



• Using default or created datums for view orientation• Dimensioning the part model as needed in the drawing • Creating drafts, rounds, and chamfers as late in the part

model as practical

• Carefully considering the options when the above guidelines

don’t make sense.


Tips & Hints

• Ways to impact text• Special Characters in a Note• Color• To Select items• Search Secrets• Dimensioning• Axis Points• View Styles• Pivot Point• Control Alt during assembly of items• Uncheck constraints to allow freedom• Use Lock Dims to assist in relocating items in a sketch


Tips & Hints

• Ways to impact text – @s = a dim will display its symbol

instead of its numeric value when shown on a drawing. Also seeing “A”, “B” and “C” is better for family tables than seeing d1245, d1342 and d879.

– @+ = superscript– @- = subscript– @# = end script change– @o = @o = replace the d with the

letter o of the created dimension and enter text, does not work on driving dimensions

– @[ = start boxed text– @] = end boxed text– To control the number of digits

displayed in a table on a drawingCreate relation to “name” = &dim#On drawing use &”name”[.7] where the 7 is the num of digs to display.


Tips & Hints

• Special Characters in a Note:

review the character map and locate the desired symbol, create a note including the cross-referenced symbols value, change the font that specific sysmbol.


Tips & Hints

• Color:

Create custom colors by copying existing ones and editing them.


Tips & Hints

To Select Items:One by One

Use CTRLEdge Loop:

Select Edge, Shift – Select 2nd Edge

Loop Surfaces:Select Surface, Shift - Select

EdgeSeed & Boundary Surfaces:

Select Seed, Shift – Select Boundary, use control to add last surface.

Edge From – To Chain:Select Edge, Shift – Select 2nd

Edge, RMB (Toggle)Solid Surface:

Select Surface, RMB “Solid Surface”


Tips & Hints

Search Secrets:CTRL – F

ComponentsFeaturesNameTypeSizeIDStatus


Tips & Hints

Dimensioning:

NOTE: CONVERT STRAIGHT LINES TO CONSTRUCTION.

Perimeter:Entity(s), Convert To,

DimensionTangent Angle:

Vertex, Entity, Entity, PlaceArc Angle:

Entity, Vertex, Vertex, PlaceArc Length:

Use Perimeter Function.

NOTE: CONVERT STRAIGHT LINES TO CONSTRUCTION.


Tips & Hints

Axis Points:Available in Internal Sketches onlyTo be used for DimensioningSchemeUseful for assemblyreferences and in patterns


Tips & Hints

View Styles:Blank, Wireframe,

Hidden, HLRBy Display

Multiple Styles available at once

User ActivatedVisible IndicationWill impact Repaint

Performance


Tips & Hints

• Pivot Pointswhen copying features in sketcher you can change the pivot point by right clicking on it and then selecting the desired location.


Tips & Hints

• Control Alt

Use control alt pressed at the same time to orient an item being added to an assembly.Control Alt & RMB to spin the item being added.Control Alt & MMB to pan the item being added.


Tips & Hints

• Uncheck constraints to allow freedom

Rather than delete constraints, uncheck them to evaluate other locations and orientations of an item.


Tips & Hints

• Use Lock Dims to assist in relocating items in a sketch

Set filter to Dims, window entire sketch, RMB and hold, select lock. Then unlock the dim controlling the location of the sketch. It can now slide in that orientation without distorting.


Web resources, Cool Links & Acknowledgements

www.ptc.com/support Knowledge Base /community Tutorials & Downloadwww.proesite.com Configs & Benchmarkwww.ptcuser.org Exploderswww.profilesmagazine.com Pro/E E-zinewww.proengineer.com Pro/E Resourceswww.mcadcentral.com Tips, Jobs, Forumswww.proe.com Tips, Forumswww.turbosquid.com/3d modelswww.mcmaster.com/ vendor items, modelswww.3dcadbrowser.com modelswww.3dcontentcentral.com/ modelswww.mcaduser.com/ modelswww.gdandt.com/quiz.htm a geometric TOLERANCING

quizwww.matweb.com/search/MaterialGroupSearch.aspx

materials properties pagewww.cad-resources.com/ tutorials

Everything in this presentation is a compilation of exposure to all of these links and fellow users and their presentations I thank them all for making their knowledge so accessible to me and YOU! I would only ask you pass on knowledge you gain to others as well.

http://www.ptc.com/support

http://www.ptc.com/support

2008 first robotics conference 3d design & practices presented by: bill samuels designer bae...

Documents

design flaws

final design

design concepts

d design practicespresented

earlier design phases

good idea design

specific sub assembly

sub assembly designs