Design Iteration and Building Robot Components

Lesson

Your first design is almost never your last. Real robots improve through many small cycles: design a part, make it, test it on the robot, learn what went wrong and refine it. CAD makes each loop faster, as long as you keep track of what changed.

Prototype, test, analyse and refine. Each pass through the loop should produce a better, named version.

History, versions and branches

History records every change automatically. Useful for undoing, but hard to read after hundreds of edits.
Named version: a permanent snapshot you create at important moments, such as just before printing.
Branch: a separate workspace started from a version, so you can try a risky idea without disturbing the main design.
Merge: if the branch idea works, you bring those changes back into the main workspace.

TEXT

1V1  First print - holes match kit pattern
2V2  Thicker plate after it bent during testing
3V3  Added slot for wire routing
4Branch: lighter-pocketed-plate (experiment)

Example of clear version names with a short note on what changed

Designing a bracket that fits your kit

1
Define the job
Write one sentence: what does this part hold, and what does it attach to? For example, a plate that holds a sensor on the side of the chassis.
2
Get real dimensions
Take the hole spacing and hole size from your kit's documentation or vendor CAD, and the mounting holes of the component from its datasheet.
3
Sketch the outline
Draw the plate shape and tie it to the origin. Use construction lines to lay out hole centres on the kit's grid.
4
Add holes and patterns
Create one hole with a sensible clearance, then use a linear pattern to repeat it along the grid.
5
Extrude and finish
Extrude to thickness, fillet sharp corners and add any slots for wires or screwdriver access.
6
Check in the assembly
Mate the bracket to the kit part and the component, look for collisions and confirm screw heads have room.

Think about how the part will be made before you finish it. The same bracket may need different details depending on the tool you use.

Method	Good for	Design tips
3D printing	Complex shapes, mounts, spacers	Parts are weaker between layers, so orient the part so loads do not pull layers apart
Laser or CNC cutting	Flat plates from sheet material	Keep the part 2D and check minimum hole and slot sizes for the machine
Hand cutting and drilling	Simple plates in aluminium or polycarbonate	Print a 1:1 drawing as a template and centre-punch holes before drilling

Document your design

Judges and future teammates want to know why your design looks the way it does. Keep screenshots of each named version, note what you tested and why you changed it, and add the story to your engineering portfolio. A short before-and-after comparison is often more convincing than a perfect final render.

Remember that robot size limits and other rules change between seasons. Before you finalise a design, check the current official Competition Manual and game materials from FIRST, and build those limits into your CAD as reference sketches.

Key terms

Iteration: One cycle of designing, making, testing and improving a part.
Branch: A separate workspace created from a version so you can try changes without affecting the main design.
Merge: Bringing changes from a branch back into the main workspace.
Hole pattern: The fixed layout of hole positions and sizes used by a kit so parts can bolt together.
Bracket: A simple structural part that holds one component in place on another.

Practical exercise

Design, version and improve a sensor or servo bracket

1Pick a real component your robot needs to mount and find its mounting hole dimensions in its documentation.
2Find your kit's hole spacing in the kit documentation and note it in your notebook.
3Design a bracket that matches both hole patterns, using fully defined sketches and a linear pattern.
4Place it in an assembly with the kit part and component, then save a named version V1.
5Create a branch, make one improvement such as reducing weight or adding wire clearance, and save it as V2.
6Write two sentences comparing V1 and V2 and decide which you would build.

Deliverable: A bracket design with versions V1 and V2, an assembly showing it mounted, and a short written comparison for the engineering portfolio.

Knowledge check

Answer every question, then check your answers.