The basic concept for this drilling frame came from Randy Knapp. Although, this one is not a work of art like everything Randy makes.
The overhead drive powered drilling frame is made from 2-1/4"x.5" 6061 aluminum tube. The tube inside diameter is bored a little to fit the outside diameter of the ball bearings. The ER20 chuck has two drive pulley choices 2.5" and 1.24" diameter. The drilling frame will fit in a Aloris type quick change tool post. The ER20 chuck will accommodate from 3/32" to 1/2" diameter tools. I really do like the even compression and self release feature of the ER spring collets.