The process starts with having the collar fastened onto the drill bit to 
the correct depth position. In this case it would be 20mm.

Up to 4 holes per side can be drilled with the 10mm brad point drill to 
the correct positions. 
The dowel centers are then inserted into the already drilled holes. It 
is used to transfer the center points to the other piece of wood.
A rubber mallet or suitable hammer can then be used to transfer the 
center marks.
Repeat step 2 to have the correct depth drilled holes on the other side.
Clean out the drilled holes of excess dust and debris.
Glue can be then be applied to the holes and the dowels can be 
inserted. Make use of clamps to keep the join secured until the glue has 
set.

Furniture shelf supports.
Supports for hanging items such as clothing, key rings, tools etc.
Joinery.