A MICROMETER BORING HEAD
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$10, postage paid in the US and Canada, plus applicable tax (Michigan)