This boring head is based (with permission) on a design by the late George Thomas.

The generously proportioned dovetail and dowelled gib, coupled with a large diameter graduated dial, make for precise and silky smooth adjustments. With this boring head, plus simple shop-made cutters (3/8"ø shanks, and, via adaptor sleeves, smaller ones as well), you can machine washer seats, cut counterbores for socket head cap screws down to 0-80, bore holes for which you don’t have a drill of the right size, and bore/counterbore holes in jobs too big to swing in your lathe.

You can use it in your vertical mill, and/or in the 3-jaw chuck in your lathe.

This is a valuable and versatile milling machine accessory that will serve you for a lifetime. I suspect you’ll learn a few things in the course of making it, too.  The instructions are very detailed, and the drawings show every part, complete with dimensions for making the Boring Head in 2 different sizes, to suit both larger and smaller mills.

US Customers: US$8 ppd
Canadian Customers: C$10.50 ppd (includes GST)
Customers outside US or Canada: C$13 ppd