openbeam compatable hole drilling guides

I have trouble drilling straight on my openbeam printed parts ,
so I made this.
Use as you like.

Note:
Added A , B , C. version3
A = for 10x15mm centre hole (5mm thick)
B = for 15x15mm centre hole (5mm thick)
C = for 15x15x15mm centre for drilling openbeam.

If your designed part is 4mm thick use A or B ,and use other hole.
If you have 9mm thickness (x15mm) use C , top hole.

Update:
may want to use a new one every 20 holes or so,
the hole will start to oval after a whil