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Module 2 — Mechanism Prototyping

Objective: validate concepts quickly before committing to CAD/fab.

Prereqs: Chosen mechanism concepts.

Steps

  • Build fast prototypes (wood/polycarb) for intake/shooter/climb ideas.
  • Measure cycle time, reach, repeatability; log jams and failure modes.
  • Adjust geometry and materials for second iteration as needed.
  • Try different compression/roller speeds for game pieces; note wear and grip.
  • Add simple sensors (beam breaks, limit switches) to validate detection points.

Instructions (numbered)

  1. Build rough prototypes quickly (wood/polycarb/3D print) for top concepts.
  2. Test: measure cycle time, reach, repeatability; log jams/failures.
  3. Vary compression/roller speed/angles; record effect on different game pieces.
  4. Add simple sensors (beam breaks/limits) to test detection and handoff timing.
  5. Decide keep/kill/iterate; note dimensions to carry into CAD.

Example

  • Intake v1: 1.1 in compression, 4 in rollers @ 3500 RPM; cones jam at 30% angle → increase flare and reduce speed to 2500 RPM.

Best practices

  • Change one variable at a time; record results.
  • Use cheap materials to iterate fast; video every test.
  • Add sensors early to prove handoff timing.

Common mistakes

  • No measurements; relying on “looks good.”
  • Not testing with worn game pieces.
  • Skipping sensor validation.

Checklist

  • Prototype built
  • Tests logged (cycle, reach, repeatability)
  • Compression/speed variants tried
  • Sensor trialed
  • Keep/kill/iterate decision
  • Key dimensions captured

Recommended tools

  • Saw/drill/riveter, clamps, tachometer, scale/tape, phone camera, simple data sheet.

Sample log (template)

  • Date:
  • Prototype version:
  • Settings tested:
  • Results (cycle/repeatability):
  • Issues:
  • Decision:

Photos/diagrams

  • [Placeholder: prototype photos with annotations]

Deliverables

  • Prototype results with keep/kill list and key dimensions to carry into CAD.
  • Video clips and notes for what worked/failed; recommended materials and durometers.

Resources

  • AndyMark parts: andymark.com
  • Thrifty Bot parts: thethriftybot.com