-ins_irad = openingcnr_dia/2 + gap;
-ins_orad = openingcnr_dia/2 + opening_height - gap;
-ins_th = ins_orad - ins_irad;
+inside_h = opening_height/2 - opening_protrh - inside_h_xgap/2;
+
+edge_or = openingedge_dia/2 + opening_protr_slop;
+
+Q0 = [ openingedge_dia/2,
+ openingedge_dia/2 + opening_height/2 ];
+
+p4p5d = [edge_or + ourcirc_r, 0];
+
+P0 = [ pivot_x, pivoting_gap ];
+P4 = Q0 - p4p5d;
+P3t = [ P4[0], Q0[1] - openingedge_dia/2 + opening_protrh
+ - intooth_top_slop - ourcirc_r ];
+P2 = P4 + [ -(inside_len - ourcirc_r*2), 0 ];
+P1 = [ P2[0], P3t[1] - (inside_h + ourcirc_r*2) ];
+
+P5 = Q0 + p4p5d;
+
+P8t = [ outside_len - ourcirc_r, P5[1] ];
+P9t = P8t + [ 0, -(strap_above + strap_th + strap_below - ourcirc_r*2) ];
+
+P9b = [ P9t[0], -P9t[1] + outside_gap ];
+P8b = P9b + [ 0, outend_height ];