Like is currently written in the Primitives Reference for studs?
Quote:These primitives must not be scaled in the {x} or {z} dimensions. Ideally they should not be scaled in the {y} dimension either, to allow the accurate substitution of chamfered studs by high-quality renderers [but this rule is flouted in the regular brick files, where stud4 is scaled by 5 to generate the underside tube].
Chris (LDraw Parts Library Admin)