Nice work mate, also nice to know that you trim your are pit hair and don't plait it.

Normaly drill bits will drift when blunt or one edge is chiped.
Can also drift if to much pressure in placed on the drill bit when first starting the hole and the drill is held at a slight angle, not easy to keep hand drills square.
Hope you have clean safty glasses to.

Looking forward to your perspex work Xion.