Boring Bar Holder
Sherline makes some nice, small boring bars for use on the lathe or on the mill with a boring head. They have a 3/8" shank with a small area ground flat for a set screw. I didn't have one of their tool posts with a 3/8" hole meant for a boring bar, so I made a holder that can be held in a normal tool post. I started with a piece of aluminum and squared up all the faces on the mill. I bored an accurate 3/8" hole using a boring head (since I couldn't yet use these bars on the lathe). I also cross drilled and tapped a hole for the set screw. The block was too tall to be clamped in the tool post, so I milled a recess on the clamped end. With the bar and holder in a tool post, I took measurements to the center line. Since it was a bit high, I milled the excess off the bottom of the holder. Click the pictures for larger images.