Do I really need one?

Okay, thanks for the explanation of the chopper.
Now, do I really need one for the plasma cutter?
Speed is not a primary concern, as we're talking like 9ipm.

Now that confusing polar thing again.
The motors my Pop has for me are listed as bipolar.
Does that automatically mean they aren't also unipolar.
From what I understand so far of what you guys have taught me,
is that you use a uniplolar motor in bipolar by not using the center tap.
(izzat correct?)
Does that mean that one that is listed as bipolar doesn't have the center
tap?

The thing that's confusing about this is -
If bipolar is better, and you use a uni as bi by dropping the center tap,
then why make it uni capable at all?

Confused,

Weyland