Íñigo Gutiérrez Febles
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Week 17

Applications and Implications

in-progress

overview.

Applications and Implications is the week where I commit, in writing, to what my final project actually is. The questions force me to stop building and answer some hard ones: what does it do, who has done it before, how much will it cost, and — most importantly — how will I know whether it worked.

The project has shifted since the original framing. I started with the idea of a four-leg, electronically height-adjustable standing desk. As the Proof of Concept (PoC) progressed, I realised the desk is just one possible combination of a smaller, more interesting unit: a single telescopic module. One module is a leg. Four modules under a tabletop become a desk. Two modules with a horizontal beam become a height-adjustable shelf. The shift in framing — from a desk to a module — is what these answers reflect.

learning objectives.

  • Define the scope of the final project in terms a third party can evaluate.
  • Identify prior art and explain how my project differs from it.
  • Plan the BOM, the processes, and the in-house vs. commodity split.
  • Translate vague aspirations (“does it help me stand more?”) into measurable evaluation criteria.

assignments.

Individual:

  • Answer the eleven questions of Applications and Implications.
  • Link the answers to the final project page.

the questions.

1. what will it do?

The project provides controlled vertical linear motion in a self-contained, addressable module.

The original framing was a four-leg, electronically height-adjustable standing desk: press up, the tabletop rises; press down, it lowers; presets store sitting and standing heights. That use case is still the demonstrator. What changed is how I think about it.

I now treat the standing desk as one possible configuration of a more general unit: a single telescopic module. One module is a vertical actuator with its own controller, position sensor and communication bus. Stack four of them under a tabletop and you have a standing desk. Pair two with a horizontal beam and you have a height-adjustable shelf or a workshop stand. Use one alone and you have an adjustable plinth for a camera, a monitor, or a plant.

So what it does is twofold:

  • At module level: raise and lower a load along a controlled, position-feedback-validated linear path, holding any commanded height, potentially coordinating with other modules over a shared bus.
  • At system level: behave as a standing desk — four synchronised modules lifting a tabletop between a sitting height and a standing height, with preset positions and manual override.

The deliverable for Fab Academy is one fully working module and a configuration of four modules acting together as a desk the future spiral.

2. who has done what beforehand?

The most directly comparable project is Arun Bobby’s Programmable Smart Desk (Fab Academy 2022, Kochi) — a height-adjustable desk with two telescopic legs, stepper motors, lead screws and a custom controller. It is the closest reference in terms of mechanical layout and electronics scope.

Other useful references:

None of these treats the telescopic leg itself as a reusable module that can be repurposed across applications, which is the contribution my project tries to make.

3. what sources will I use?

I work with two layers of sources.

Technical: datasheets and reference designs (TMC2209, A4950, VL53L0X, XIAO RP2040, Touch sensors), the Fab Academy KiCad libraries, and prior Fab Academy student documentation from León and other labs.

Mechanical and methodological: my own background in industrial automation (intralogistics, PLC-based positioning systems) for the control-loop side, manufacturer drawings for commercial parts (T8 nut, 608ZZ bearing, NEMA 17), and direct calliper measurement for every part that touches a tolerance.

Local instructors at Fab Lab León (Nuria, Pablo, Adrián) are the human source layer for fabrication decisions.

4. what will I design?

I design the module itself, not the desk. The desk is one configuration; the module is the designed object.

In detail, that means:

  • The mechanical body — nested PVC tubes for the PoC, square steel tubes for the eventual production version — plus all the 3D-printed PETG parts that interface the tubes with the leadscrew, motor and bearings.
  • The driver/controller PCB — designed in KiCad 10, milled and soldered at Fab Lab León.
  • The firmware — module-level firmware on the XIAO RP2040.
  • The inter-module protocol — in case of getting to a second module, a UART bus with software addressing that lets several modules coordinate as a synchronised group.

The standing-desk configuration of four modules is the demonstrator. Designing the module — not the desk — is what makes the project reusable across the other configurations (shelf, stand, plinth) without redesign.

5. what materials and components will be used?

Structural:

  • PVC evacuation tubes (EN 1329) for the PoC body — DN32 inner, DN40 mid, DN50 outer if a third stage is added.
  • Wood (plywood or MDF) for the module base and top, CNC-milled.
  • In a future production iteration these would be replaced by steel square tube (60/50/40 mm, 2 mm wall, EN 10219, powder-coated matte black).

Actuation:

  • NEMA 17 stepper motor (started with Usongshine 17HS4023 then upgraded to LDO 42STH48).
  • TR8×8 leadscrew with T8 brass flanged nut.
  • 5×8 mm flexible coupling.
  • 608ZZ ball bearings.

Electronics:

  • Custom PCB designed in KiCad 10 and milled in-house on the Roland MDX-20 at Fab Lab León.
  • XIAO RP2040 as the per-module controller.
  • TMC2209 SilentStepStick for stepper driving.
  • Two touch sensors for manual up/down override.

3D-printed parts: PETG on a Bambu Lab A1 — nut block, top bearing bracket, motor mount, top cap, touch sensors and PCB supports. All modelled parametrically in Fusion 360.

6. where will they come from?

Mostly local suppliers, with a clear preference for Spanish and EU sources:

I stay within the EU for shipping and customs reasons.

7. how much will they cost?

A detailed BOM is maintained in the project documentation and updated as components are purchased. The current estimated cost per module is approximately 80–120 € at prototype quantities, broken down roughly as:

BlockApprox. cost
NEMA 17 + leadscrew + nut + coupling + bearings25–35 €
PCB substrate + SMD components + connectors15–25 €
XIAO RP2040 + TMC2209 + VL53L0X20–30 €
PVC tubes + fasteners + 3D-printed PETG10–15 €
Misc. (wiring, buttons, heat-shrink)5–10 €

The full standing-desk configuration is therefore in the order of 400–500 € in components, excluding the tabletop. This is a current best estimate, to be refined as purchases are made.

8. what parts and systems will be made?

Made in-house:

  • Mechanical parts: all 3D-printed PETG components, modelled parametrically in Fusion 360 and printed on the Bambu Lab A1.
  • Electronics: the custom driver/controller PCB, designed in KiCad 10 and milled on the Roland MDX-20.
  • Module base: CNC-machined from wood at Fab Lab León.
  • Firmware: for both the XIAO RP2040 module controller and the ESP32-S3 master, written in C++ on the Arduino framework.

Bought as commodity items: motor, leadscrew, nut, bearings, inserts, connectors, fasteners, PVC tubes.

9. what processes will be used?

  • Additive manufacturing: FFF 3D printing in PETG (Bambu Lab A1) for all custom mechanical brackets.
  • Subtractive manufacturing: CNC machining of the wood base; manual cutting and drilling of PVC tubes.
  • PCB milling: single-layer FR1 board on the Roland MDX-20, followed by manual SMD soldering.
  • Embedded programming: firmware development for RP2040.
  • Mechanical assembly: press-fits, self-tapping M3 screws into PVC, machine-thread M3 into PETG, manual leadscrew alignment.

10. what questions need to be answered?

The project answers questions on two levels.

Technical questions:

  1. Speed. Does the module achieve a useful linear speed (~25–30 mm/s) with the chosen TR8×8 leadscrew and NEMA 17 combination?
  2. Load. Can a single module hold and move 25 kg vertically without stalling, missing steps, or overheating the driver?
  3. Position accuracy. Does the step-count detect and correct positioning drift reliably?
  4. Synchronisation. Can four modules coordinate over the UART bus to move together without measurable racking of the tabletop?
  5. Safety on power loss. Does the leadscrew system hold position under a 25 kg load when power is cut, or does the load back-drive the screw? TR8×8 is a fast lead and not self-locking, so this is a real risk that needs measurement — and possibly a mechanical brake or a switch to a self-locking lead profile in the final design.
  6. Thermal behaviour. How hot do the TMC2209 and the NEMA 17 get under a duty cycle representative of office use (a few full-stroke movements per hour)?

Use-level questions:

  1. Does daily access to a standing position actually change how often I stand while working?
  2. Do I notice differences in posture, hip mobility or lower-back discomfort over weeks of use?

The technical questions are the ones the project is evaluated against during Fab Academy. The use-level questions are the motivation behind the project, and the answers will become visible only after months of use.

11. how will it be evaluated?

Evaluation is anchored to the technical questions in §10, each one paired with a concrete measurement:

QuestionEvaluation methodPass criterion
SpeedMeasure full-stroke time with a stopwatch≥ 20 mm/s sustained
LoadApply a calibrated 25 kg mass and run a full up/down cycleCompletes without stalling or step loss
Position accuracyStep count after 10 full cyclesDrift < 2 mm
SynchronisationMeasure height of all four corners after a 4-module moveMax deviation < 1 mm across corners
Power-loss safetyCut power at mid-stroke under 25 kgEither holds position, or descent is controlled and bounded
ThermalIR-thermometer reading after 1 h of representative duty cycleTMC2209 ≤ 80 °C, NEMA 17 ≤ 70 °C

A module is considered successful if it passes all six criteria. A full standing-desk configuration is successful if four synchronised modules pass criteria 1–6 in combination.

reflections.

The most useful thing about this week was being forced to write down the pivot. I had been silently shifting from “I’m building a standing desk” to “I’m building a telescopic module that happens to be configured as a desk” for weeks, but I had not written it anywhere. The act of reflecting about this topic with my local instructors made the pivot clear to me, and that changed how I read every other answer.

Surely more modifications and changes will come across due to the time limitations until the final presentation, but these are my goals an this point.