On 20 Nov 2004 12:21:02 -0800, (Wally
Blackburn) vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

I am going through the throes of the same process.

You are right. As has been said you need ratio reduction. For metal
you need slow speeds and high pressures/torque.

For stainless and other harder metals, the slower the better for your
blades. I have be3en advised to start at about 40-50 SFPM for what I
am doing (bit tougher than stainless)

You could use a gearbox, or belt for the first reduction, and then
chain for the final drive. I was going to use belt to do this. But
belts get more and more slippy as they get slower on smaller and
smaller pulleys. So gears or chain.

You would also benefit from at least a spray bottle with some cooling
oil, which you spray on at regular intervals. This lubricates and
cools. Not a bad idea to have something on the lower wheel to
brush/scrape the residue off the tyre, either.

I have one of the old Delta 14" wood bandsaws that I am using for
metal cutting. I am using a 3-phase 1HP motor with a VFD - so I can
slow the motor way down for metal.

To be honest, I've never used a bandsaw before, so I am learning the
hard way, and I think I just huffed my first blade (14-18TPI Morse
Bi-Metal). Anyway, I was just guessing at speeds to run the motor,
and I thought I would calculate the SFPM to see where I really needed
to be. Looking at the speeds metal bandsaws are advertised at, I
think I need to slow down. Could you guys just check my math?

- Bandsaw drive wheels are 14" diameter. 2 * pi * r = 44" or approx.
3.7'

- Motor has 2.5" pulley, pulley on bandsaw wheel is 6" for 0.42
reduction

So, if a rev of the drive wheel moves the blade 3.7' and it is driven
at 0.42 of motor speed, SFPM should be (3.7)(0.42)(Motor RPM), or
approx. 1.5 * Motor RPM.

If that's true, getting the fastest speed of a Wilton metal bandsaw
(278 SFPM), I would have to run the motor at 185 RPM! If my calcs are
correct, then I need more reduction between motor and drive shaft.

Does this sound right, or am I missing/misunderstanding something?

Thanks,
Wallace