# CADRS considers another kernel: from OpenCASCADE to Solidcore

- Link: https://opensourcecad.nl/en/cadrs-considers-another-kernel-from-opencascade-to-solidcore/
- Published: 2026-10-22T21:42:29+02:00
- Author: Marijn van den Heuvel \+ AI

_This is the English reading version of the Dutch news item [CADRS overweegt een andere kernel: van OpenCASCADE naar Solidcore](https://opensourcecad.nl/vibecoded-apps/cadrs-kernelwissel-solidcore/)._

[CADRS](https://opensourcecad.nl/en/mechanical-product-design/) is an open-source
parametric CAD program: sketches, constraints, features, assemblies and technical
drawings, with a workflow you know from Onshape. It models on the OpenCASCADE kernel.
In the project’s development discussion the question is now on the table whether
to trade that kernel in for **Solidcore**.

Solidcore is a rebuild in Rust of SMLib, the kernel part of NVIDIA’s open-source
USD BRep project. The first customer is sister project SolidCraft, which wants to
replace its own Truck kernel with it. Solidcore’s progress page counts 261 parts:
108 are done, 89 partial, and about 70% of the lines have been ported. That page
is rebuilt after every change.

Why that matters: the kernel is the part that actually makes your model. A fillet,
a boolean, an offset and the export to STEP come out of it. If something goes wrong
there, it is not your sketch failing but the kernel underneath. The reporter estimates
that about a third of the failed operations in SolidCraft sit in the kernel. The
maker of CADRS keeps it short: OCCT is somewhat slow, and a switch is in principle
the conversion of one module.

Meanwhile he is not sitting still. He has spent a few days on a kernel of his own:
OpenCASCADE again in Rust, intending it to compute on the graphics card instead 
of the processor. That kernel now has to pass the whole OpenCASCADE test set. His
interim position on Solidcore: too young and too strongly interwoven with SMLib 
to take code from, at most the surface intersection and the point projection will
be usable as a reference later.

**My verdict:** this is the discussion that really matters in open-source CAD. The
kernel decides what your model can handle, and OCCT is a commercial organisation
where doing business is a burden. Just do not let the outcome be a production plan
yet: Solidcore is not finished, and a kernel that computes on the graphics card 
is for now in the test phase of one maker.

What a kernel does and why the choice is so decisive is on [NURBS & modeling kernels](https://opensourcecad.nl/en/nurbs-modeling-kernels/).
How I test this kind of switch is on [Tests & benchmarks](https://opensourcecad.nl/en/tests-benchmarks/).**
Keep an eye on this site for updates and tests**, I keep following CADRS and publish
here what the kernel switch delivers.