English Tech/Engineering Mechanics / Mech Engineering pipe-bursting

1. Clamp the sub-saver in the rear rod vise
2. Using an acetylene heating torch, evenly and quickly apply heat to the threaded joint to loosen the threads. Apply heat only to the ***box end*** of the sub-saver. The thead locking compound will release at 500° - 600° F (260° - 315° C)
3. Quickly back the drive chuck out of the sub-saver before the heat transfers to the spindle shaft.

...end towards the box or boxed end (and in this case what's a boxed end?)