To effectively attach a metal pipe to cutting, it must be clamped in the jaws of a table vise with prismatic jaws, which will securely jam and prevent it from turning. The simple jaws of an ordinary vise will not provide a secure fit. But on top of them it is enough to slide two blocks of hard wood with triangular prismatic cuts of the appropriate size. Even a thin-walled tube can be clamped between such blocks of wood.
