Simple chess board adjustable in FreeCAD

I liked the simplicity of bjared's single square with dovetails and finishing edges, but the tolerances used with his CR-10 back in 2018 are something like 0.5mm and the pieces didn't hold together at all when printed on my Prusa CORE One in 2025. So I redrew it in FreeCAD, making a VarSet to hold various parameters, and found that I could reduce the clearance -- made by reducing the pin only of the dovetail joints -- to only 0.05mm.

After assembling the board, I found it acquired a very slight downward curvature for which I'm blaming overextrusion of the topmost perimeters of the squares. I added a chamfer to the top of the squares you could enable; setting square_top_chamfer to 0.1mm would probably be plenty if this is the cause (I have not tested it), but I left it at 0.0001mm, effectively disabling it, so the FreeCAD file matches the STLs I exported. 

To export STL files accurately from FreeCAD 1.0, 1) activate the Mesh workbench, 2) go to Edit/Preferences/Import-Export, select "Mesh formats" in the left panel (appears only after the Mesh workbench has been activated) and 3) set the "Maximum mesh deviation" parameter to 0.0100mm.

While the edges do fit on the CORE One's bed diagonally, adhesion in the corners was a problem, so I just went ahead and split them in the slicer. I've included that .3mf file.

Assuming you go with a standard 8x8 board, you'll need to print 32 squares in each of two colors (64 total). I did this in batches of 16. You'll need two (2) side_pins and two (2) side_tails.

I've included .stl files exports with clearances of 0.2mm, 0.1mm, and 0.05mm. The side_tails works with all clearances; only the pins change with clearance.

Photo shows pieces from https://www.printables.com/model/856037-another-set-of-chess-pieces/comments

Category: Chess

Redrawn and parameterized in FreeCAD to allow tighter tolerances.