QymCAD

A parametric associative CAD on a B-rep kernel

Sketch → part → assembly. One program, one project file, no cloud and no subscription.

cad.qymis.tech

English | Русский | Українська | Қазақша

What it is

QymCAD is a desktop CAD 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, patterns. Parts come together into an assembly through joints — revolute, slider, rigid. The model is parametric: change a dimension in any operation and everything below it in the timeline rebuilds, the assembly included.

The geometry is exact and solid (B-rep), computed by the OpenCASCADE kernel — the same one FreeCAD runs on. Hence precise surfaces instead of meshes, correct fillets and exchange through STEP with other CAD systems.

The interface is available in English, Kazakh, Ukrainian and Russian.

Status

A development build. The program works and is fit for real parts, but it is updated daily.

• The document format changes with no backward compatibility. A file saved by an earlier version may not open. For such files there is the convert_qcad.py script (see below).
• The CNC (CAM) module does not work. The settings do carry a “Machining” tab (CAM) checkbox, but what is behind it is groundwork: part of the code came from an earlier version and is not maintained. The module returns for the stable alpha.
• The macOS build is not signed by Apple. It is signed and whole, but with a certificate Apple did not issue, so on the first launch macOS says it cannot verify the app and refuses to open it. It is allowed once, with the "Open Anyway" button in System Settings -> Privacy & Security; the steps are in the notes beside the app.

Features

Sketching. Lines, arcs, circles, ellipses, splines, polygons, slots, text. Constraints and dimensions are solved together; dimensions are parametric (w/2, sin(a)). There is construction geometry and the projection of a body's edges into the sketch.

Parts. Extrude, revolve, sweep, loft, fillet (including a variable radius set at vertices), chamfer, shell, draft, holes (plain, counterbored, countersunk), thicken, patch, stitch, trim, split of faces and of a body, face copy and face push, linear and circular patterns, mirror, booleans, and the primitives: box, cylinder, sphere, cone, torus, prism. Threads are built from a real helical profile with run-outs.

Assemblies. Parts and sub-assemblies, joints (rigid, revolute, slider, cylindrical, planar, ball, pin-slot, parallel), limits and drives, degrees of freedom, an interference check. A sketch can be placed on the face of a neighbouring part as an associative reference: change the neighbour and the dependent part rebuilds.

Exchange. STEP (import and export), STL (import and export), DXF and SVG (import and export of sketches). Either the whole project or a single part or sub-assembly picked in the tree can be written out.

Installation

The builds are in Releases. No extra libraries are needed: OpenCASCADE and the dependencies are inside the package.

Windows 10/11 x64 — qymcad-win64.zip. Unpack anywhere and run qymcad.exe.

Linux — qymcad-*.AppImage, a single file. Requires glibc 2.35 or newer: Ubuntu 22.04+, Debian 12+, Fedora 36+, Arch.

chmod +x qymcad-*.AppImage
./qymcad-*.AppImage

macOS 12+ — for Apple Silicon (M1 and later) qymcad-*-macos-arm64.dmg, for Intel qymcad-*-macos-x86_64.dmg. Open the disk image and drag QymCAD onto Applications. The first launch is refused once, because the build is not signed by Apple: press "Open Anyway" in System Settings -> Privacy & Security. The README folder beside the app walks through it step by step, in every language of the program.

Help

The built-in help opens with F1. The articles, with illustrations, live in docs/help.

Project files

A document is saved as .qcad. The format changes directly, with no compatibility layer; documents from earlier versions are brought forward by a separate script:

python3 convert_qcad.py part.qcad    # converts in place, keeping part.qcad.bak beside it

The script brings a document forward from any earlier version in one pass and is idempotent.

Building from source

Linux — just pkg-linux, Docker required. Windows — MSVC with the kernel built from source. macOS — the kernel from source as well, then packaging/macos/bundle.sh. The details are in packaging/README.md.

The kernel is OCCT 7.9.3, built from source with the cmake line given in packaging/README.md. A package of OCCT from a system may differ in three ways that matter: another version (the program is written and tested against 7.9.3; another one gets a warning at the build); BUILD_RELEASE_DISABLE_EXCEPTIONS left at ON (OCCT's own checks are compiled out, and a degenerate input is no longer refused); signals not converted (OCC_CONVERT_SIGNALS; a fault inside OCCT then closes the program instead of being refused).

Contributing

See CONTRIBUTING.md.

Licence

The code is distributed under AGPL-3.0-or-later: a fork and any derived build stay under the same licence with open sources.

The OpenCASCADE kernel comes under LGPL-2.1 with an exception and is linked dynamically; the fonts and the icons come under licences of their own. All of it is listed in THIRD-PARTY-NOTICES.md, and that file is placed beside the program in every package.

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QymIs Tech — qymis.tech. Author: Denis Kazachenkov.