Design and fabrication of a workshop test bench that merges pneumatic, water, and electrical circuits into a single station, driven by a 3-position selector switch. Still in production at the original customer site 6 years later. BTS technical degree internship, France, 2019-2020. Anonymized case study.
🇫🇷 Version française disponible : README.fr.md
| Before | After | |
|---|---|---|
| Test stations | 2 separate benches (pneumatic on one side, electrical on the other) | 1 unified bench |
| Test time per unit | 3 h 50 | (gain not measured at the time — see lessons 2026) |
| Procedure errors | Missed steps (station switching = loss of focus) | Linear procedure, mandatory checklist |
| Cost | — | ~€500 |
| Status | — | Continuously in production since 2020 (6 years) |
A French distributor of imported medical equipment was assembling units (heavy professional equipment) from parts, testing them, and shipping to end customers. Each unit required two separate validations — a pneumatic + water test, then an electrical leakage test with a Fluke-class instrument — on two physically distant benches. Technicians lost focus between stations, missed steps, and the full test took 3 h 50 per unit.
I was tasked (intern, BTS year 2, 20 years old) with redesigning the process. Budget cap : ~€500. My solution : one bench combining both tests, driven by a 3-position Lovato selector switch (0 = off / 1 = pneumatic + electrical simultaneously / 2 = electrical leakage test). Integrated 230 V → 24 V transformer, autonomous water reservoir (2 bottles including a purge cycle), color-coded tubing. Built on two reclaimed bathroom tables (drilled and integrated).
| Doc | Content | Lang |
|---|---|---|
docs/00-problem.md |
Existing-state analysis : the 2 benches, the friction, the numbers. | 🇬🇧 |
docs/01-apte.md |
APTE functional spec (FP / FC, F0-F3 flexibility classes). Methodology → apte-toolkit. | 🇫🇷 (EN translation pending) |
docs/02-architecture.md |
Solution architecture : functional schema, choice of selector, water/electrical integration. | 🇫🇷 (EN pending) |
docs/03-test-protocol.md |
One-page A4 test procedure (step-by-step, anti-omission). | 🇫🇷 (EN pending) |
docs/04-assembly-tracking.md |
Per-unit assembly tracking sheet : SN traceability per instrument. | 🇫🇷 (EN pending) |
docs/05-lessons-2026.md |
The bridge document — what I'd do differently 6 years later, and the connection to my current AI hardware lab. | 🇬🇧 |
photos/ |
Anonymized photos of the bench (interior, front panel, plumbing). | — |
The APTE framework (French functional analysis method) used here is codified separately in apte-toolkit. This repo is the applied example (anonymized) of that toolkit.
If you're starting a test bench / instrumentation / industrial rig from scratch, read apte-toolkit first, then come back here to see what a real-world filled spec looks like.
This 2020 bench is the seed of a journey I continue today in my home AI hardware lab (ENYOLAB — public repos coming):
- 2020 : a bench that measures (Fluke, pressure, function).
- 2026 : a bench that measures AND stores data in structured form — USB oscilloscope, SCPI multimeter, sigrok logic analyzer, micro USB camera — where an AI agent reads the bench in real time and writes results to a queryable store.
The underlying goal is the same : validate a physical system rigorously. The difference : 2020 produced dead PDFs archived in a desktop folder. 2026 produces living data that powers predictive maintenance, traceability, and potentially AI-driven service troubleshooting.
See docs/05-lessons-2026.md for the honest detailed bridge.
In line with my confidentiality obligations (internship, company data, GDPR) :
- The customer company's name is not disclosed.
- The OEM equipment manufacturer's name is not disclosed.
- Names of people (colleagues, management) are not mentioned.
- Addresses, financials, customer references are removed.
- Proprietary part references are replaced with generic descriptions.
- Published photos are cropped / blurred to remove identifying logos and labels.
The methodology and the design are mine and remain freely publishable.
CC BY 4.0 — Nevil Bofumbo, 2026. Reuse freely with attribution.