I anticipate the boring bar to protrude 5" or 6 " from my OXA tool holder and have a diameter of 1/2" or 5/8" 2 10° y y y Small Boring Bar Series Features MICRO-MINI TWIN a1 tool offering 2 cutting edge types. Where it protrudes from the … Clear the hole to make sufficient diameter in the bar by using a 6 foot long, 1 1/8 inch diameter extension drill. I want to make a boring bar for my 7" x 12" lathe, my thinking is to make up some small HSS cutters that will be inserted into the bar and locked in place with a grub screw. Mounting the round tool on the lathe toolpost requires a separate adapter. Make sure that the hole is clear and insert the boring bar. Reduced tooling costs, economical • Boring Minimum cutting diameter ø2.2mm-Nose R: 0.05, 0.1, 0.2 In making my custom boring bar, I decided to mill a square shank that would directly fit the minilathe toolpost without needing an adapter. Step 3 – Line Up Bar. Standard boring bars have a round shank with a typical diameter of 3/8 or 1/2 inch. Align it carefully and make sure it lies centrally in the drilled hole.