CADHans JohnsonBuild/Design CaptainFRC 3018 Nordic Storm2013 Lake Superior Excellence in Engineering Award2013 10,000 Lakes Engineering Inspiration Award2013 Championship Xerox Creativity Award

Why do we use CAD? Model robot

Concepts Testing Iterations Modifications between tournaments

Make drawings Sponsor machining

Organization Nordic Storm’s 2013 Robot had over 100 parts and sub-

assemblies Each subsystem was assigned a prefix

A = Actuation C = Climber D = Drivetrain DMP = Dumper P = Positive Engagement R = Full robot assembly Followed by name of part, e.g. C_ClimberPivotPlateLeft

Each subsystem had an assembly, combined into full robot assembly

Dropbox Nordic Storm uses dropbox to sync and back up our CAD

files Offers 30 day version control Free 2GB of space, invite other members to get more space

Allows everyone to work from one set of files, rather than moving them around on a flash drive

Our Process Drivetrain CADed within the first couple days Manipulator/superstructure designs in parallel with

prototyping of mechanisms Once full robot model is largely complete, parts that will be

manufactured by sponsors are sent off For parts made in house, drawings are made and reviewed

by a mentor before being printed and given to student machinist.

As parts are assembled, tested, and the design is modified, the CAD model is updated nightly

Simulation FEA Size Motion

FEA Finite Element Analysis Used to determine stresses on parts Will a part hold up under expected load?

Change material (AL vs Steel) Increase thickness Shows points of high stress

Size Does the robot fit within size limitations Frame perimeter easy to measure Our articulating robot fitting within cylinder

Motion Simulate motion of mechanisms Do parts collide? Cam system on this year’s robot when folded

Are there collisions?

Gotchas/Tips and Tricks Design some tolerance into your parts

Holes on laser cutting/waterjet should be cut small and drilled/reamed to size Nesting parts – blocks into tubing Clearances between moving mechanisms

Things get bent, make sure it won’t break something else if it does Things won’t be perfect, make sure your design can handle that

Electronics boards Make sure they aren’t an afterthought and there is enough space for everything Make sure they are accessible

Battery It’s big and heavy, use it to your advantage and include it in your design

Inventor has a CoG calculator. Use it! Many COTS parts have CAD models available that can be imported

AM McMaster 3D Content Central

Frame Generator Inventor has a built-in frame generator Provide a skeleton, and Inventor will create the proper

lengths of tubing, pipe, extrusion, bar stock, etc

Drawings Drawings are made for all parts machined in house or sent to

sponsors with material Part files sent for laser and CNC

After part is created and design is reviewed by multiple students and mentors, a drawing is created

Drawing is then checked to ensure it is complete before printing

Each drawing has a revision number in the title block to avoid confusion between multiple versions of the part – updated every time the drawing is printed