On Thu, 13 Sep 2012 14:25:30 -0700 (PDT), whit3rd
wrote:

On Monday, September 10, 2012 7:06:49 PM UTC-7, Tom Gardner wrote:
I have a 7.5 hp 36" Tannewitz vertical band saw [for wood]
Could I put a VFD on it to cut metal?

Yes, but to set a VFD to 1/10 speed (about what the steel-cutting
recommendation is) you'll get similar motor torque and current limits,
but lower speed and voltage. That means torque x speed,
or equivalently current x voltage, is about 1/10 of the
'7.5 hp' rating, and you'd be cutting with effectively three
quarters horsepower.

Not bad, actually; you don't WANT to zip through steel like
it was hardwood. Handling steel stock that needs a 36" throat
is gonna be a team-building experience.

If you can make it fit, you are far better to get a gearmotor that
drops into that location with the right shaft diameter and length.
Then the motor stays at it's native 3450 or 1725 and you get the right
FPM on the bandsaw blade.

It would be lovely if they made one big bandsaw design with a
car-style 4-speed transmission, then you just shift it to the right
speed range and put on the right band. If it's heavy and rigid
enough for steel, wood would be cake.

-- Bruce --