A browser-based parametric designer for a classic solid-tube Newtonian telescope on a Dobsonian mount. You enter a handful of dimensions; it derives every plywood part, shows the assembled scope in an interactive 3D viewer, checks that nothing collides as the tube swings, and exports cut-ready DXF files for the wooden parts.
The optical/tube math (aperture, focal length, spacing) is assumed solved elsewhere (e.g. newt-web); this tool's value is the mount structure → cut list / DXF.
⚠️ Warning. This project was created using Claude Code. The generated DXF files have not been tested in a real CAD/CAM application or used to cut actual parts. Treat all output as unverified: open the DXFs in your own software, check every dimension, and cut test pieces before trusting them. No warranty — see LICENSE.
- Parametric geometry — tube cradle, three-sided rocker box with a circular bearing saddle, and a round ground board, all derived live from your inputs.
- Balance by sliding — the tube slides in the cradle to balance; the altitude axis is placed from a balance-point percentage rather than a full CG/mass solve.
- Joinery — selectable box (finger) joints at the cradle and rocker-front corners, and tabs-in-slots attaching the sides/front to the bottom disk. Joints are part of the 2D outline, so they flow straight to the DXF.
- Rigorous interference check — a conservative-advancement sweep over the full altitude range (0°–90°) that is certain, not sample-based, and reports the minimum swing clearance and the angle it occurs at.
- 3D viewer — orbit, swing the altitude/azimuth, per-group visibility toggles, and a "distinct part colors" mode to make the interlocking joints obvious.
- DXF export — one R12 DXF per plywood part (outlines, bolt/pivot holes, tab slots,
altitude-center markers), bundled into a single timestamped
.zip(e.g.dobsonian-parts-2026-06-24_143007.zip). Units are inches. The zip also carries an embeddeddobsonian-design.jsonso the design that produced it is recoverable. - Save / restore — export the design parameters as a
.json, and re-import later from that file or by dropping the DXF.ziponto the 3D view. Imported values are validated and clamped to range; only the design parameters are stored (not view state). - Persistence — parameters, pose, visibility, and display options are saved to
localStorageand restored on reload.
Every plywood part is prismatic — a 2D profile polygon (with holes) extruded by a
constant thickness, then placed. From that one record the app derives the 3D mesh, the
flat outline, the DXF, and the collision geometry, so they cannot drift apart. There is no
heavy CAD kernel; the domain is prismatic by design. See dob-design-spec.md for the full
rationale, formulas, and the tripwire: if any part ever needs a genuine 3D solid
(fillets, lofts, compound curves), this architecture should be reconsidered.
It's a static site using ES modules and an import map for three.js (loaded from a CDN), so
it must be served over HTTP — opening index.html via file:// will not work.
python3 -m http.server 8017
# then open http://localhost:8017/Any static file server works. The only runtime dependency is three.js, pulled from a CDN
by the import map in index.html.
| File | Purpose |
|---|---|
index.html |
UI shell, control panel, three.js import map |
js/params.js |
input definitions, defaults, fixed constants |
js/geometry.js |
the geometry engine — derived dimensions and part assembly |
js/joinery.js |
finger/box joints, tabs, and matching disk slots |
js/interference.js |
conservative-advancement swept collision check (SAT-based) |
js/viewer.js |
three.js rendering, visibility groups, color modes |
js/dxf.js |
minimal R12 DXF writer |
js/zip.js |
dependency-free store-method ZIP writer + reader |
js/main.js |
UI wiring, persistence, export |
dob-design-spec.md |
the consolidated design spec and decision record |
Implemented: inputs + validation, parametric geometry, joinery, interference check, 3D visualization, and DXF export. STL export is shelved (the side bearings are produced by another process and modeled here as placeholder cylinders). Deferred niceties: kerf compensation, finger fit allowance > 0, and tuning a few flagged default constants.
Public domain — released under The Unlicense. Do whatever you like.