On Sat, 11 Jan 2014 16:48:51 -0800, DaveC wrote:

A friend (in USA) with a 220v, 1-phase horizontal bandsaw in his home machine
shop wants to replace the 1/4 hp motor with 1/2 hp and rewire with an
auto-off switch (when the blade cuts through the metal).

I always default to using a 3-wire control with contactor, but he asks the
logical question: "Why?"

Other than the "If the power fails while cutting" answer (which he says seems
of limited additional value on a saw with auto-stop feature) I wasn't very
convincing.

What are the arguments for using a contactor as opposed to a simple on-off
switch of equivalent rating?

Thanks.
The simplicity and safety of using low voltage controls instead of
requiring heavy duty limit switches. One adequately sized contactor
and as many microswitches as you want as controls to turn it on or
off, running at low voltage and low current.