Router Bit Holder

The outer diameter is 15 mm for all designs. you can use 15 mm forstner bit to make holes on any board.The holder will fit snuggly to board.
ID Inner Diameter for 1/2 in shank bit is 13 mm.
ID for 1/4 in shank bit 7 mm
ID for 12 mm shank bit is 12.6 mm.
ID for 8 mm shank bit is 8.4 mm.
Fusion 360 files are in thing files so you can change the design.