💰 Budget & Funding · All Roles · Intermediate

BOM → Notebook: CSV to Cost Table

🗺️ Flowchart — BOM (Bill of Materials) → notebook entry

A BOM lists every part on the robot. The notebook captures it for budget tracking AND so anyone can recreate the design.

flowchart TD
    Start([New part used on bot]) --> Capture[Capture during build:
name, vendor, part number,
cost, quantity]
    Capture --> Cat[Categorize:
Structural / Motor / Sensor /
Pneumatic / Electrical / Misc]
    Cat --> Log[Log to BOM sheet
spreadsheet or notebook table]
    Log --> Q1{Major part
or minor?}
    Q1 -->|"Major"| Photo[Add photo + sketch
to notebook entry]
    Q1 -->|"Minor"| TableOnly[Just add to BOM table]
    Photo --> Done([Logged])
    TableOnly --> Done

    style Start fill:#1e293b,stroke:#22d3ee,stroke-width:2px,color:#e2e8f0
    style Done fill:#1e293b,stroke:#22c55e,stroke-width:2px,color:#e2e8f0
    style Q1 fill:#fbbf24,color:#0f172a,stroke:#fbbf24

Turn the Onshape BOM export into a readable subsystem cost table that helps explain actual resource constraints and design decisions. Formatting alone does not determine a rubric score.

The rubric connection: Use the current GRSF rubric guide when reviewing evidence of criteria and constraints. Record cost constraints when they actually influenced a decision, not as a retroactive story. A BOM that appears after your mechanism choices is accounting. A BOM that precedes them — and that you reference in your decision matrix — is evidence of engineering judgment.

🔄 Step-by-Step Workflow

Export the CSV from Onshape. In the BOM panel: three-dot menu → Expand All → three-dot menu → Export to CSV. Save it. Open in Google Sheets (File → Import, or drag it into Drive).

Add the four columns you need. After importing, add these columns to the right of the existing data: Unit Cost, Total Cost (= Qty × Unit Cost), Supplier, Notes. If you used the Description pipe-encoding from the Onshape BOM guide, use =SPLIT(D2,"|") to extract cost into its own column automatically.

Enter unit prices. Fill in the Unit Cost column for each row. Use vexrobotics.com for current prices — note the date you checked. District-provided items (Brain, Controller, batteries) should be listed at their real price with a note "District provided — not from team budget."

Create subsystem subtotals. Group rows by subsystem (Drivetrain, Intake, Arm, Electronics, Hardware). At the bottom of each group, add a subtotal row using =SUM(). Subsystem totals can make budget tradeoffs easier to explain; this layout is a Spartan suggestion, not a required judging format.

Add the "Considered but not chosen" section. Below the main BOM, add a second table: alternatives you evaluated and their cost. This is the single highest-value addition you can make to your notebook BOM. See format below.

Screenshot or export to PDF, then insert into notebook. Format your Sheets so it looks like a clean table (freeze header row, alternate row colors, bold subtotals). Screenshot the whole table or export as PDF. Insert into your notebook at the Identify the Problem / Criteria & Constraints section — before your mechanism selection.

📊 Google Sheets Template Layout

Historical practice BOM — Push Back 2025–26; verify current parts, prices and Override legality

#	Assembly / Part	VEX Part #	Qty	Unit Cost	Total	Supplier	Notes
DRIVETRAIN
1.1	V5 Smart Motor 11W	276-4840	4	$40.00	$160.00	VEX	600 RPM (blue)
1.2	4" Omni Wheel	276-3526	4	$15.00	$60.00	VEX
1.3	Al C-Channel 2×35h	228-3540	4	$6.50	$26.00	VEX	Lighter than steel
DRIVETRAIN SUBTOTAL					$246.00
INTAKE
2.1	V5 Smart Motor 11W	276-4840	2	$40.00	$80.00	VEX	200 RPM (green)
2.2	Flex Wheel 2.5"	393-0014	8	$5.00	$40.00	VEX
INTAKE SUBTOTAL					$120.00
ELECTRONICS
3.1	V5 Brain	276-4810	1	$350.00	$350.00	VEX	District provided
3.2	V5 IMU Sensor	276-4855	1	$30.00	$30.00	VEX
ELECTRONICS SUBTOTAL					$380.00
GRAND TOTAL (excl. district items)					$638.00

⚖ The "Considered but Not Chosen" Section

Show the alternatives the team actually considered and how cost affected the decision. Place this evidence beside the relevant design choice. Do not invent alternatives to complete a template.

Alternatives Considered — Drivetrain

Alternative	Cost	Why Evaluated	Why Not Chosen
6×11W Drivetrain	$400	More pushing power, faster recovery from defense	$160 over budget; need motors for intake mechanism. For Override 2026-27 also illegal under R11a (55W drivetrain cap).
Pneumatic actuated intake	$130	Faster deployment, no motor allocation	Single-use per match without pump; adds $80+ kit cost
Steel C-channel frame	$18 (vs $26 Al)	Lower cost, more available	Added 0.4 kg — reduces top speed by ~8%. Not worth $8 savings.

Why this evidence helps: a comparison can explain alternatives and reasons for selection. Current GRSF rubric scores depend on the evidence across the notebook, not on adding a particular table.

❌ Brief vs. Evidence-Rich — Side-by-Side

✗ Proficient (what most teams write)

"Here is our parts list. Total cost: $950." [single table, no subsystem breakdown, appears after build section, no alternatives listed, no constraint statement up front]

✓ Specific evidence (illustrative, not a score guarantee)

"Our budget constraint is $700 for build components (district covers Brain, Controller, batteries). This eliminates 6×11W configurations on cost grounds — and for Override 2026-27 specifically, R11a's 55W drivetrain cap eliminates them on rule grounds as well. Here is our BOM by subsystem showing we came in at $638 — $62 under budget for mid-season replacements. Alternatives considered and rejected on cost or rule grounds are listed below."

Timing matters: The BOM must appear in the notebook before your mechanism selection entry. A cost constraint written after the decision isn't a constraint — it's a record. Judges know the difference. Write the Season Budget Statement on kickoff day, and the BOM right before your decision matrix.

⚙ STEM Highlight Engineering: Configuration Management & Parts Traceability

A Bill of Materials is a configuration management document — the same artifact used in aerospace, automotive, and medical device engineering to maintain a complete, versioned record of every component in a system. Configuration management ensures the physical robot can be reconstructed from the BOM without ambiguity, and every change is traceable. In regulated engineering, components without a traceable BOM record are considered uncontrolled.

🎤 Interview line: “We maintain a live BOM in Onshape that updates with every design change. Every physical robot we have built can be traced back to a specific BOM version. When we needed to replace a motor at competition, we had the exact part number and supplier on hand because the BOM was current. This is the same configuration management discipline aerospace engineers use.”

Your Onshape BOM has 14 parts. Which of these belong in a notebook entry?

⬛ All 14 — every part must be documented

⬛ Only the most expensive parts to show budget awareness

⬛ Custom-fabricated parts and any part where a trade-off was made between alternatives — purchased standard hardware goes in the Appendix BOM, not individual entries

📝

Notebook entry tip: Appendix — Grey slide — Export your Onshape BOM screenshot and paste it into the Appendix. Annotate which parts are custom-fabricated vs purchased and flag any where a cost trade-off was documented elsewhere. A BOM that is updated each design version — V1 BOM, V2 BOM — shows how parts and costs evolved with the design.