QymCAD
Parametric associative 3D CAD on a real B-rep kernel (OpenCASCADE), with assembly and rigid-joint support.
What it does and how it connects
QymCAD is a desktop CAD program for mechanical parts and assemblies: housings, brackets, mechanisms, printed and milled work. A sketch becomes a solid by extruding, revolving, or sweeping; the solid takes holes, fillets, a shell, and patterns. Parts come together into assemblies through joints (rigid, revolute, slider, cylindrical, planar, ball, pin-slot, parallel), with limits, drives, degrees of freedom, and an interference check. The model is parametric: change a dimension in any operation and everything below it in the timeline rebuilds, the assembly included.
Geometry is exact and solid (B-rep), computed by the OpenCASCADE kernel, the same one FreeCAD runs on, so surfaces are precise instead of meshes and exchange runs through STEP. The program also imports and exports STL, DXF, and SVG, and writes out a whole project or a single picked part or sub-assembly. The interface is in English, Kazakh, Ukrainian, and Russian, and there is no cloud and no subscription.
The README is candid about status: it is a development build, fit for real parts but updated daily, and the document format changes with no backward compatibility, with a convert script for older files. The CAM module does not work yet, and the macOS build is not signed by Apple, so the first launch needs an Open Anyway step.
What engineers report
When a parameter moves or resizes the source of a sketch pattern, the source follows and the copies do not follow it. If the pattern's count and step are unchanged, the copies stay where they were.
2026-11-05Read the original
Alternatives
Compare side by side- OpenSuperCAD
An agent-driven editor on top of OpenSCAD, rather than a parametric B-rep CAD program with its own kernel.
- MusubiCAD
A parametric CAD plugin for coding agents, rather than a standalone desktop CAD program.
- PartCAD
A parametric CAD package for parts and assemblies, rather than a B-rep desktop CAD with joints and interference checks.
- freecad-ai
AI assistance for FreeCAD, rather than a standalone CAD program on the OpenCASCADE kernel.
Recurring errors it addresses
Error Index entries this tool is built to reduce or work around.
- Extruded text whose height follows a parameter scales the glyphs but silently drops some letters or swaps them for the hole inside an A or B, with the rebuild reporting no error.Error Index
- A custom external thread 0.04 mm deep with a 0.1 mm fit on a d8 shaft should cut to a root radius of 3.86 mm or less but cut to 3.9466, because the kernel guessed the cutter side from the profile's extents and, when depth plus fit was smaller than the cutter overshoot, took an external thread for an internal one and moved the relief outward, with no rebuild error.Error Index
- QymCAD Recognise only accepts a body that is the direct output of the mesh import. A Move makes a new body id, so the moved mesh is refused, though the model itself still knows it is a mesh. Suppressing that Move then fails with Source body not built and shows the mesh twice.Error Index
Sources
Not verified
- Pricing: none stated on the repo or site; the README states no cloud and no subscription.
Last verified November 6, 2026. Listings are informational. The evidence score measures public, verifiable evidence and is not an endorsement or a compatibility claim.