fix pin cut

ball-amort/ball_amort.scad

@@ -146,6 +146,7 @@ module half_pin(friction = false) {
       translate([0, 0, 8-0.8]) cylinder($fs=0.5, h=0.8, r=2.9);
     }
     translate([0, 0, -0.2]) cylinder($fs=0.5, h=8+0.2, r=2.4-0.8);
-    translate([-0.5, -5, -0.1]) cube(size=[1, 10, 4]);
+    translate([0, 0, 4-0.5]) rotate([90, 0, 0]) cylinder($fn=4, r=0.5, h=8, center=true);
+    translate([-0.5, -5, -0.1]) cube(size=[1, 10, 3.6]);
   }
 }