High School / HS-03
Available Grades 9–12 Robotics & controls
Build a 3-joint servo arm, derive its forward and inverse kinematics, and measure how far the gripper lands from commanded targets.
Laue Labs · HS-03 · Status: in technical review (not released, no price set).
Students build a laser-cut, three-joint arm (base yaw, shoulder, elbow) that holds a pencil over an engraved target board. They derive forward and inverse kinematics with right-triangle trig and the law of cosines, calibrate each servo against real angles, then measure accuracy and repeatability on 25 engraved targets the way industry measures robot arms, and fit corrections from their own data.
BOM.md.Students will:
Every high school pack includes worked math and physics, prediction-versus-measurement labs, at least two design-and-test iterations, data logging, a rubric, and documentation templates, plus printable Builder's Corner build journal pages.
Parts, specs, quantities, and estimated unit costs, with places to buy. Prices change; anything marked as an estimate is an estimate. Links were checked when the BOM was written.
Totals are computed from the line items below. Prices were read from vendor pages on the dates shown and will change. Rows tagged estimate have no verified link and are planning numbers only.
| ID | Part & spec | Qty | Unit (typical) | Line (typical) | Where to buy | Cheaper substitute | Adult handling / safety gear |
|---|---|---|---|---|---|---|---|
| E1 | ESP32 Feather V2 (controller) Adafruit PID 5400 · USB-C; includes male header (not needed here: the Feather gets female headers) | 1 | $19.95 | $19.95 | adafruit.com Adafruit $19.95 · checked 2026-10-09 · In stock | Adafruit HUZZAH32 Feather (PID 3405); same code, same Wing | Header soldering: adult supervision, eye protection, ventilation |
| E2 | 8-Channel PWM/Servo FeatherWing (PCA9685) Adafruit PID 2928 · 12-bit, I2C 0x40; ships with 2 × 3x4 straight headers, 2-pin power terminal block (reverse-polarity protected), header stick; 50.8 × 22.9 mm, 3.9 g | 1 | $9.95 | $9.95 | adafruit.com Adafruit $9.95 (qty 1–9) · checked 2026-10-09 · In stock | Generic PCA9685 16-channel breakout + jumpers (same library; not priced) | Soldering (see E1) |
| E3 | Feather female header kit Adafruit PID 2886 · 12 + 16 pin; soldered on the Feather so the Wing plugs on top | 1 | $0.95 | $0.95 | adafruit.com Adafruit $0.95 · checked 2026-10-09 · In stock | Solder the Wing directly to the Feather (not removable) | Soldering (see E1) |
| E4 | USB-A to USB-C data cable Adafruit PID 4474 · ~1 m | 1 | $4.95 | $4.95 | adafruit.com Adafruit $4.95 · checked 2026-10-09 · In stock | Any USB-C data cable you own (low total assumes owned) | — |
| E5 | M2.5 nylon screw + standoff set Adafruit PID 3299; mounts the Feather stack on the board | 1 | $16.95 | $16.95 | adafruit.com Adafruit $16.95 · checked 2026-10-09 · In stock | Double-sided foam tape (low total; not priced) | — |
| Subtotal | $52.75 | Low-cost path: $30.85 | |||||
| ID | Part & spec | Qty | Unit (typical) | Line (typical) | Where to buy | Cheaper substitute | Adult handling / safety gear |
|---|---|---|---|---|---|---|---|
| S1 | Standard servo FEETECH FS5106B (base yaw + shoulder) Pololu 3425 · 40.8 × 20.1 × 38 mm, 43 g; 4.8 kg·cm @ 4.8 V, 6 kg·cm @ 6 V; 180° over 500–2500 µs (FEETECH sheet A/0; older units 700–2300 µs); stall 1.8 A @ 4.8 V; 3.3 V signal OK; horns + hardware included; 30 cm lead | 2 | $22.58 | $45.16 | pololu.com Pololu $22.58 each · checked 2026-10-09 · In stock | FEETECH FS5103B (Pololu, lower torque, not priced) or any standard-size 180° analog servo ≥ 3 kg·cm — re-measure µs/deg in Lab 1 | Keep fingers out of the joints while powered |
| S2 | Micro servo FEETECH FS90 (elbow) Pololu 2818 · 23.2 × 12.5 × 22 mm, 9 g; 1.3 kg·cm @ 4.8 V; ~120° over 900–2100 µs; stall 600 mA @ 6 V (Pololu test); horns + hardware included; 8 in lead | 1 | $8.40 | $8.40 | pololu.com Pololu $8.40 · checked 2026-10-09 · In stock | Any 9 g micro servo with the same body size; plastic-gear clones have more backlash (Lab 4 will show it) | — |
| S3 | Servo extension cable 50 cm (2) Adafruit PID 973 · elbow and shoulder leads reach the Wing with an 80 mm service loop for ±80° base rotation | 2 | $2.50 | $5.00 | adafruit.com Adafruit $2.50 each · checked 2026-10-13 · In stock | — | — |
| S4 | 5 V 4 A switching power supply (servo power) Adafruit PID 1466 · UL listed, 5.5/2.1 mm centre-positive plug, ~5 V up to 4 A | 1 | $14.95 | $14.95 | adafruit.com Adafruit $14.95 · checked 2026-10-09 · In stock | A bench supply set to 5.0 V with a 3 A current limit | Mains plug-in brick: adult checks the cord; no open mains wiring anywhere in this kit |
| S5 | DC jack to screw-terminal adapter Adafruit PID 368 · 2.1 mm female jack | 1 | $2.00 | $2.00 | adafruit.com Adafruit $2.00 · checked 2026-10-09 · In stock | — | Check polarity with the multimeter before connecting the Wing |
| S6 | Silicone wire 20 AWG (red + black pair) RaceDayQuads 2 ft pair, 20 AWG option · adapter (S5) → Wing terminal block, ~15 cm | 1 | $1.99 | $1.99 | racedayquads.com RaceDayQuads $1.99 (20 AWG option) · checked 2026-10-09 · In stock (some gauges showed out of stock) | Any 20–22 AWG stranded wire | — |
| S7 | Electrolytic capacitor 1000 µF, ≥ 10 V, low-ESR (required) Soldered into the Wing's V+ capacitor footprint (observe polarity); supplies servo current peaks (3 servos can stall at ≈ 4.4 A, above the 4 A supply) | 1 | $1.00 estimate | $1.00 | Electronics supplier (no link) — | 470 µF minimum | Observe polarity; adult checks before power-up |
| Subtotal | $78.50 | Low-cost path: $78.50 | |||||
| ID | Part & spec | Qty | Unit (typical) | Line (typical) | Where to buy | Cheaper substitute | Adult handling / safety gear |
|---|---|---|---|---|---|---|---|
| M1 | Baltic birch plywood 3 mm, 12 × 20 in Wood Vault, Laser/CNC grade 1/8" variant. Cut files use 2 sheets; 1 spare for fit tests and mistakes | 3 | $3.50 | $10.50 | woodvault.com The Wood Vault $3.50 per sheet (1/8" Laser/CNC grade variant) · checked 2026-10-09 · Not confirmed (page contains a 'Sold out' label for at least one variant) | Any laser-grade 3 mm birch | Laser: trained adult operator, ventilation |
| M2 | Small wood screws / M2 × 8 screws for servo ears and horns ~20 pcs; the servos' own horn screws are used at the splines | 1 | $4.00 estimate | $4.00 | Hardware store (no link) — | Servo-included screws often suffice for the ears | — |
| M3 | Wood glue (aliphatic) Laminations and tab joints | 1 | $6.00 estimate | $6.00 | Hardware store (no link) — | Shared with other packs | — |
| M4 | Zip ties, small (≤ 2.5 mm) + pencil (HB, round) Pencil held on link 2 by two zip ties: snug, so it slides back instead of breaking if pushed into the board | 1 | $3.00 estimate | $3.00 | Any (no link) — | Shared | — |
| M5 | C-clamps (2) or 4 wood screws — fix the board to the table The arm can tip a loose board | 2 | $6.00 estimate | $12.00 | Hardware store (no link) — | Strong double-sided tape (low total) | — |
| Subtotal | $35.50 | Low-cost path: $14.50 | |||||
| ID | Part & spec | Qty | Unit (typical) | Line (typical) | Where to buy | Cheaper substitute | Adult handling / safety gear |
|---|---|---|---|---|---|---|---|
| T1 | Safety glasses, ANSI Z87.1 Z87+ (high-impact) (soldering, cutting) 3M SecureFit SF201AF · clear anti-fog polycarbonate lens marked Z87+ (ANSI Z87.1 impact-rated; 3M spec table on strobelssupply.com and safetycompany.com, read 2026-10-09) | 2 | $5.32 | $10.64 | platt.com Platt Electric Supply $5.32 EA · checked 2026-10-09 · 40 in stock (company-wide) | Any glasses marked Z87+ (ANSI Z87.1 high-impact). Not SparkFun SWG-11046: it lists only CE/EN 1836, a sunglass standard, not impact-rated | Required while soldering and trimming |
| T2 | Temperature-controlled soldering iron Pinecil | 1 | $68.50 | $68.50 | sparkfun.com SparkFun $68.50 · checked 2026-10-09 · Not recorded | Any temperature-controlled iron the school owns (low total assumes owned) | Adult supervision, eye protection, ventilation |
| T3 | Lead-free solder 15 g SparkFun | 1 | $4.95 | $4.95 | sparkfun.com SparkFun $4.95 (single-unit price) · checked 2026-10-09 · Not recorded | — | Wash hands after soldering |
| T4 | Digital multimeter Polarity and voltage check of the servo supply | 1 | $21.50 | $21.50 | sparkfun.com SparkFun $21.50 · checked 2026-10-09 · Not recorded | Assumed owned in the low total | — |
| T5 | Digital calipers 150 mm Measure L1, L2, Z0, E and dot offsets | 1 | $19.95 | $19.95 | sparkfun.com SparkFun $19.95 (single-unit price) · checked 2026-10-09 · Not recorded | Steel rule + magnifier (±0.5 mm): Lab 4 uncertainty doubles | — |
| T6 | Small screwdrivers, hobby knife, sandpaper, masking tape Assembly and cleanup | 1 | $12.00 estimate | $12.00 | Any (no link) — | Assumed owned in the low total | Knife: cut away from the body |
| T7 | Laser cutter access or cutting service 2 sheets, 3 mm birch, cut + engrave | 1 | $10.00 estimate | $10.00 | Makerspace / cut service (no link) — | — | Trained adult operator |
| Subtotal | $147.54 | Low-cost path: $45.54 | |||||
The pack is digital files only. Hardware is bought separately.
These are standards the pack's activities are mapped to by Laue Labs. They are not a certification or endorsement by any standards body or state.
The activities below are mapped to these standards by Laue Labs. This is an alignment aid for teachers. It isn't an official certification or endorsement by NGSS, Achieve, NGA/CCSSO, or any state. Check against your state's adopted standards.
| Performance expectation | Where it shows up |
|---|---|
| HS-ETS1-2: design a solution to a complex real-world problem by breaking it down into smaller, more manageable problems | Base angle → planar two-link IK → limits → calibration |
| HS-ETS1-3: evaluate a solution based on prioritized criteria and trade-offs | Lab 5 accuracy target vs. time; joint-space vs. straight-line moves |
| HS-ETS1-4: use a computer simulation to model the impact of proposed solutions | ik_tools.py workspace, sensitivity and path predictions before motion |
| HS-PS2-1 (supporting): forces and torques | Static torque budget for the shoulder and elbow servos |
Science and engineering practices: developing and using models; planning and carrying out investigations; analyzing and interpreting data; using mathematics and computational thinking.
| Standard | Where |
|---|---|
| HSG-SRT.C.8: use trigonometric ratios and the Pythagorean theorem to solve right triangles | Base angle with offset, r = √(ρ² − E²) |
| HSG-SRT.D.10/11: prove and apply the Laws of Sines and Cosines | Elbow angle from the law of cosines |
| HSF-TF.A.2 / HSF-TF.B.7: unit circle; use inverse functions to solve trigonometric equations | atan2, two elbow branches |
| HSN-VM.A.1–3 (+): vectors, components | Tip position as sum of link vectors |
| HSS-ID.B.6: fit a function to data | Lab 1 pulse-vs-angle line fit |
| HSS-ID.A.2–4: center and spread; standard deviation | Lab 4 AP and RP |
| HSN-Q.A.1–3: units, quantities, appropriate accuracy | Every lab table |
One student or one household.
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One homeschool family, or one co-op group of up to 10 learners with its facilitator(s).
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One teacher with up to 30 students in a single class or cohort.
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All licenses: digital files only (hardware not included). Keep Laue Labs attribution on printed handouts. After checkout you get an instant download on the thanks page. License questions, more learners, or site licenses: lance.haney@gmail.com.