So ... The original ones would be a cut 10" sq (finished up at 9.5) with a cut 14.75 setting triangle so ... at a cut 7" (finished up at 6.5) square for Dec A the setting triangle would be cut at 10.5" then cut on the diagonal both ways (like an X ). When I do setting triangles I always cut them larger (I would cut min of 11" sq here ). As far as the HSTs ?? I assume that you are referring to the corner setting triangles / for a 6.5" finished sq, those would be cut at 5.5" with one cut on the diagonal .