💰 Budget & Funding · All Roles · Intermediate
BOM → Notebook: CSV to Cost Table
You exported the Onshape BOM to CSV. Now turn it into a clean, subsystem-organized cost table that belongs in your engineering notebook — and that pushes your Criteria & Constraints rubric score to Expert.
The rubric connection: The RECF Engineering Notebook rubric's Criteria & Constraints row rewards teams who established cost as a constraint before making design decisions. 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.
1
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).
2
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.
3
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."
4
Create subsystem subtotals. Group rows by subsystem (Drivetrain, Intake, Arm, Electronics, Hardware). At the bottom of each group, add a subtotal row using =SUM(). This is the structure judges look for — not a single grand total, but per-subsystem visibility that shows you budgeted at the subsystem level.
5
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.
6
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
| # | 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
This is the section most teams skip — and it's the one that moves a notebook from Proficient to Expert on the rubric. Judges want to see that you evaluated alternatives. Add this table directly below the BOM, before your mechanism selection section.
| Alternative | Cost | Why Evaluated | Why Not Chosen |
|---|
| 6-Motor Drivetrain | $400 | More pushing power, faster recovery from defense | $160 over budget; need motors for intake mechanism |
| 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 matters to judges: The "Alternatives Considered" section directly satisfies the rubric's requirement to show that all solutions were evaluated before one was selected. A team that lists only what they built has an incomplete Design Process. A team that documents what they considered and why they rejected it has an Expert-level notebook.
❌ Proficient vs. Expert — 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]
✓ Expert (what judges score highly)
"Our budget constraint is $700 for build components (district covers Brain, Controller, batteries). This eliminates 6-motor configurations. 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 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.
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.