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Stage 4 — Manufacturing & Sourcing

Window: Week 2 through Week 4 (overlaps with CAD). Gate: Bill-of-Materials Complete. Precondition: Subsystem CAD Lock passed.

Small teams win manufacturing by not machining what they can buy, and by ordering early enough that a lost package does not sink the season.

Core Policies

COTS First

Buy before you machine. Vendors we trust:

  • WCP (WestCoast Products) — drivetrain, gearboxes, shafts.
  • REV Robotics — motors, motor controllers, structural components.
  • AndyMark — wide catalog, drivetrain kits.
  • The Thrifty Bot (TTB) — inexpensive alternatives, swerve, telescopes.
  • VEXpro — motors, gearboxes, controllers.
  • AndyMark, McMaster-Carr — fasteners, stock material.

Elite teams' bills-of-material are 60–80% COTS. Machining a gearbox plate that WCP sells is a wasted week for a small team.

Two-Copy Rule

For every part on the robot, order enough for:

  • Practice robot (or drive base at minimum).
  • Competition robot.
  • Spares — one full spare of anything that can break (belts, wheels, chain, common bolts, at least one of every custom-machined plate).

Even if only one robot is built, order the parts. Reorder lead times kill events.

Order Cadence

Batch orders twice per week — pick fixed days (e.g., Monday + Thursday). Prevents:

  • Multiple $12 shipping charges for individual parts.
  • "We ordered it yesterday" excuses.
  • Forgotten-item panic on Friday afternoon.

Purchasing student maintains a running order queue. Anyone can add; only Mentor Lead + Purchasing Student can submit.

Kanban Board (physical whiteboard in shop)

Columns:

CAD Released Ordered In Machining Ready Assembled

Each column holds a card per part with part number, owner, and quantity. A part exists in exactly one column. Card moves as state advances.

  • CAD Released: part number assigned, drawing exists, not yet purchased/queued.
  • Ordered: vendor order placed, or on machining queue with assigned operator.
  • In Machining: on a mill, lathe, printer, or laser right now.
  • Ready: part in the shop, labeled, in the correct bin.
  • Assembled: installed on robot.

Rule: stand-up meetings walk the board. Any card stuck in one column > 3 days gets escalated.

Machining Priority

When a machinist has time, priority order:

  1. Long-lead custom parts (waterjet outsourced, anodized).
  2. Structural drivetrain parts (blocks all assembly).
  3. Custom parts for the primary scoring mechanism.
  4. Everything else.

Never machine "the easy fun part" first while structural parts wait.

Deliverables (Bill-of-Materials Complete Gate)

  • BOM covers practice + comp + spares.
  • All long-lead items (> 5 day lead time) ordered by end of Week 3.
  • Machining queue populated with drawings and quantities.
  • Kanban board reflects current state (audit weekly).
  • Total spend within team budget; mentor signoff on cost.

Common Failure Modes

  • Machined a COTS part. Days wasted, worse tolerances than vendor.
  • Single copy ordered. One shipping loss = season delay.
  • Ad-hoc ordering. Fifteen individual shipments, over budget.
  • Kanban maintained on someone's laptop. Board must be visible in the shop — everyone updates as they pass it.
  • Forgot fasteners. Always order bulk hardware early; small parts vanish.
  • Waterjet vendor lead-time surprise. Confirm turn-around before designing dependent parts.

Roles

  • Purchasing Lead (student): owns the order queue and BOM.
  • Fabrication Lead (student): owns machining queue and kanban.
  • Machinist Mentor: trains students, gates access to mill/lathe, enforces safety.
  • Business/Finance Mentor: tracks spend against budget.

Handoff to Stage 6 (Integration)

Kanban says "Assembled" for all subsystem parts. Subsystem is now integratable. See 06_integration_testing.md.

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