After the beam removes 0.15 mm, tab and slot both finish at 7.50 × 3.0 mm for a glue-free press fit. Measure your kerf: cut a 20 mm square, then kerf = 20 − measured width.
Wood flexfrom the bend test
Cut the bend test (Hinge tab) and pick the highest zone that bent cleanly. 100% suits good Baltic birch; above that the hinge uses fewer cuts and bends tighter, below it the spacing closes up to protect weaker wood.