On 2012-09-11, Tom Gardner Mars@Tacks wrote:
I have a 7.5 hp 36" Tannewitz vertical band saw that we don't use much
any more. We used it for production wood cutting and it zinged through
5/4 hardwood like butter.

Could I put a VFD on it to cut metal?

I presume at 7.5 hp it is a three-phase motor? A single phase
can't benefit from a VFD -- especially a capacitor start one.

You could slow it way down with a VFD (if you set up something
to blow air through the motor to keep it cooled), but you would not get
the torque needed to seriously cut metal

If it has variable speed build in (adjustable pulleys for about
half the range, and a two-speed gearbox which can be shifted for
switching between the high and low speeds), then is is already capable
of metal cutting as it is -- just put the right blade on it and set the
speed properly.

Note that both the variable speed pulleys and the gearbox
increase torque as they decrease speed -- which is what you need here.

A quick search on the brand shows a range of sizes bandsaws, all
with fixed blade speeds, and the 36" one shows a 10 HP motor, not 7-1/2
HP, but that could be difference in time of manufacture. It looks as
though all of their stuff is made for woodworking only.

I'm not sure whether the speed is sufficient to allow friction
cutting of steel. That is done with a toothless blade (or a regular one
quickly becomes toothless at those speeds in steel) which melts its way
through the workpiece.

Good Luck,
DoN.

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