Quick & dirty broring head made as one of first tools to use with
"new" mill-drill ca. 1986.  leadscrew is 3/8- 24tpi socket head capscrew
with brazed on collar to actuate crosslide; and flange, never marked with
increments.  Basic design works fine.  With access to a lathe, a better
screw, 20, 25 or 40 tpi would be in order.