On Sat, 20 Nov 2004 12:21:02 -0800, Wally Blackburn wrote:

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.

A wood cutting bandsaw is going to run in the 2500-3000sfpm range. Your's
as set up is running at 2650sfpm. So to get into the right range you will
need to be running the motor a bit above a tenth of its normal speed
(180rpm). So yes your calculations are okay.

At that speed you'll have pretty much no torque avalailable from the
motor (if it will even run that slow). So to do metal cutting at those
speeds you need a 10:1 speed reducer in the powertrain. And given the
torque needed it really should be a gear reducer directly coupled to the
lower bandsaw wheel. I can state from experience that you can't push
enough torque through the 6" drive pulley with a belt (it slips).

--
The instructions said to use Windows 98 or better, so I installed RedHat.