+module ScrewHole(){
+ xd = (screw_head_dia-screw_dia)/2;
+ translate([0,0,-50])
+ cylinder(h=100, r= screw_dia/2, $fn=20);
+ hull(){
+ translate([0,0,-xd])
+ cylinder(h=1, r= screw_dia/2, $fn=50);
+ cylinder(h=20, r= screw_head_dia/2, $fn=50);
+ }
+}
+