Pyslvs-UI VS FreeCAD_assembly3

> If you like Linkage, you might also like Solvespace.

No, I mean Brent Curry's Linkage[1] bicycle design software, not David Rector's Linkage Mechanism Designer and Simulator[2].

You should read Wikipedia article.[0]

N.B. About SolveSpace, as I'm its experienced user[youtube,patreon], I may say next: yes, it could be used for bike mockup, as any other CAD, but it still has a lot of limitations and even does not export correct STEP files yet[3], and in FreeCAD such STEP could fixed only partially.[video]

So, for serious 3D CAD work I highly recommend use FreeCAD (and LibreCAD for 2D CAD work) instead of SolveSpace, and use SolveSpace only as a helper tool like a calc or as a notepad for noting ideas.

About Linkage Mechanism Designer and Simulator, it is only useful for planar (2D) kinematics analyze, and if You are looking an alternative for it take a look on Pyslvs[4], that is in part based on SolveSpace's solver.

[0] https://en.wikipedia.org/wiki/rattleCAD#History

[1] https://bikechecker.com/

[2] https://blog.rectorsquid.com/linkage-mechanism-designer-and-...

[3] https://github.com/solvespace/solvespace/issues/206

[4] https://github.com/KmolYuan/Pyslvs-UI

[video] https://www.youtube.com/watch?v=F3LJMeqUDrU

[youtube] https://www.youtube.com/@appsoft

[patreon] https://patreon.com/app4soft

N.B.: There are few other projects which is using SolveSpace's libslvs, for example Pyslvs - an open source planar linkage mechanism simulation and mechanical synthesis system.

> There's something so satisfying about mechanical linkages

On Wikipedia some other mechanical linkages also described.[0]

If you want dive into kinematics try also Pyslvs[1,2] app.

[0] https://en.wikipedia.org/wiki/Category%3ALinkages_%28mechani...

[1] https://pyslvs-ui.readthedocs.io

[2] https://github.com/KmolYuan/Pyslvs-UI

If the general python API isn't enough the assembly3 docs have an interesting example which might give you some ideas for moving objects along within their constraints.

I think Realthunder's branch may have midpoint constrain you're looking for (https://github.com/realthunder/FreeCAD_assembly3/issues/51).

Also if you use this fork of freecad: https://github.com/realthunder/FreeCAD_assembly3/releases its much better at letting you attach sketches to faces without it borking things.

Take a look: https://github.com/realthunder/FreeCAD_assembly3/wiki/Topological-Naming-Algorithm

FreeCAD is still in development and you may have a mismatch of versions. Try .17, .18, .19, and .20 dev versions and try to find the one that doesn't show empty sketches. It may have even been made with the RealThunder branch.

Fusion 360 is probably the best choice to start. It's free and easy to use. But there are quiet heavy limitations as autodesk changed their licenses. I recently switchend from fusion to freeCAD and I'm pretty happy with it. I highly recommend Linkstage3, a freeCAD fork by a guy called realthunder. https://github.com/realthunder/FreeCAD_assembly3/releases

If you haven't already, take a look at Realthunders Linkstage branch. That's the one I usually use, although it can lead to adapting design practices that are not ideal.

FreeCAD fork linkstage3 supports expressions for patterns which I imagine would allow you to do this.