screw_nut_across = 7.9 + 0.75;
screw_nut_th = 3.9 + 0.75;
-knob_behind_across_space = 12.2 + 0.75;
+knob_behind_across = 12.2 + 0.75;
behind_knob_th = 5;
clamp_min_width = 20;
main_r = tube_dia/2 + main_th;
screw_max_y_lhs = -main_r -screw_nut_across/2;
-screw_max_y_rhs = -main_r -knob_behind_across_space/2;
+screw_max_y_rhs = -main_r -knob_behind_across/2;
screw_y = min(screw_max_y_lhs,
screw_max_y_rhs);
-bot_y = screw_y -max( screw_nut_across, knob_behind_across_space/2 )
+bot_y = screw_y -max( screw_nut_across/2, knob_behind_across/2 )
-minor_wall_min;
holder_x_sz = bank_x_sz + bank_recess_dx*2;