What is SolveSpace?

SolveSpace is a libre and open-source parametric computer-aided design application that uses a NURBS geometric kernel, allowing it to represent curved surfaces exactly. It was originally released by Jonathan Westhues under the GPLv3 license. M-Labs contributed to its development around 2015-2018.

SolveSpace development at M-Labs has now been discontinued; please visit for the latest information about SolveSpace. This page is kept for historical purposes only.

What can be done with SolveSpace?

SolveSpace is primarily useful for mechanical design. At M-Labs, we use it to design vacuum chambers as well as custom fittings and fixtures. The models can then be exported as STEP or PDF with dimensions and sent to a machine shop for manufacturing.

Fittings and adapters

Of course, most vacuum chambers would have some standard flanges. These can be easily modelled using a single sketch and a lathe operation:

(The illustration on the right is "live"; it can be panned, rotated and scaled.)

In a similar way, an NW160 viewport and an adapter with an NW160 flange, a KF40, two KF25 and two KF16 ports were designed:

A vacuum chamber

The fittings above were designed to be used with a cylindrical vacuum chamber, 200mm long with two NW160 flanges, two KF40 and one KF25 ports:

Cryocooler refilling fixture

To repair a broken Ricor K526S crycooler, it was necessary to disassemble it, which of course meant it was depressurized. To evacuate it and eventually refill with helium, a special fixture was designed, as the cryocooler's filling port is just a hole in the case with a set screw. Further, an adapter that allows to insert the cold head into a vacuum system via a KF25 port was also designed.

First, the cryocooler and its cold head were modelled to verify fits:

Then, a fixture was designed, shown below with a cutout (blue). It consists of a bracket, a piston case that screws into the bracket (the thread is not modelled), a piston with a retaining screw, a retaining washer, a Swagelok fitting attached to the orange port (not modelled), and a few compression gaskets (also not modelled). The bracket and the piston case hold the cryocooler The retaining washer prevents the piston from being ejected by high pressure helium and, conversely, together with another washer prevents the piston from being sucked in and blocking the gas flow during evacuation.

The KF25 adapter for the cold head is a much simpler device:

Development by M-Labs

As originally released, SolveSpace was far ahead almost every other FLOSS CAD by virtue of its parametric nature, exact internal representation of curves and a codebase easy to work with. (The only other FLOSS parametric CAD that uses a NURBS representation, including NURBS booleans, is FreeCAD.) While it was already suitable for practical work, it had a much greater unrealized potential.

Thus, M-Labs developed many additional features:

  • Native Linux (GTK) and OS X ports;
  • stippling as well as outline and hidden line styling in preparation for export of shop drawings according to ISO or another standard;
  • WebGL export using Three.js, whhow the interactive models on this page work;
  • DXF export that preserves the ability to edit the drawing afterwards, by mapping parametric constraints to DXF dimensions and grouping the lines;
  • DXF import that automatically infers (some) constraints, such as horizontal/vertical, point-coincident, linear and angular dimensions from DXF geometry and dimensions;
  • internationalization;
  • and many other minor ones.

SolveSpace development at M-Labs has been discontinued; please visit for the latest information about SolveSpace.