1" shank with a 1-1/4-12 thread — straight threaded shank.
A straight threaded shank is the arbor that holds a threaded-shank cutter. The plain 1" end goes into your holder or collet; the cutter screws onto the 1-1/4-12 thread at the other end and seats against the 1-1/2" shoulder, which is what squares it to the axis and takes the cutting load.
The shank is 2" long with 3/4" of thread. High-speed steel throughout.
What screws onto it. Any of our 1-1/4-12 outside chamfering mills: 3" at 60°, 3" at 90°. The number is the largest work diameter each one fits over.
