Loading project Things
Imported hardware project from GitHub.
Loading README and project media…
A large, inexpensive, slow-but-accurate robot arm.
The thesis: hobbyist robot arms today cluster around ~2 ft reach, ~2 lb payload, ~$2,000. By trading away speed — and only speed — we aim to beat that on every other axis: longer reach, higher payload, much lower cost, built from plywood and NEMA 17 stepper motors, with closed-loop optical feedback making up for the compliance of a lightweight structure.
| Doc | Contents |
|---|---|
| docs/vision.md | The design thesis and its four pillars |
| docs/requirements.md | Draft requirements (unknowns marked TBD) |
| docs/sensing.md | Sensing concept: unloaded-reference optical metrology |
| docs/tooling.md | Modeling & CAD tooling: TS/three.js engineering model, OpenSCAD, Python analysis |
| docs/roadmap.md | Phased plan from concept convergence to working demos |
| docs/reduction-trade.md | Phase 1a: reduction mechanism trade study and measurement plan |
| docs/open-questions.md | Decisions and details still to be resolved |
model/ holds the interactive concept model (TypeScript +
three.js, fully client-side — see docs/tooling.md):
counterweight sizing, joint torques and margins, and traverse times,
computed live over a crude 3D view with sliders. A second page, the
CAD twin (twin.html), renders the actual OpenSCAD assembly —
rigid-body meshes exported from cad/arm/ — posed live by the
four joint angles.
Both pages are live:
cd model
npm install
npm run export:cad # render cad/arm/ into the twin's meshes (needs OpenSCAD)
npm run dev # interactive, http://localhost:5173
npm test # model-core unit tests
npm run build # static site in model/dist/
The twin's meshes render at twin fidelity ($twin in
cad/arm/params.scad): features that exist to make a
part work rather than to be seen — the drums' helical cable groove, the
gears' involute flanks — get coarse tessellation, because on screen they are
worth a few pixels and cost six figures of triangles. Print and cut exports
never go through export.scad, so they keep full manufacturing fidelity.
export:cad reports each body's triangle count against a budget and fails if
one is blown, so a CAD edit can't quietly make the twin unrenderable. The
viewer has a matching mesh-stats HUD (the pose panel's mesh stats
switch, or ?stats=1): triangles per rigid body, then per part — click one to
isolate it in the scene, or focus the camera on it.
npm run export:cad:full # same assembly at FULL print fidelity, for comparison
That render deliberately overruns the budget and the viewer labels it; it is a measurement, not something to deploy. Today: 616k triangles at full fidelity vs 140k at twin fidelity, for no visible difference.
Concept stage (July 2026). Documents are drafts; the engineering model is scaffolded and working; no hardware is built yet.