[berkelusa]

I have a 1956 14" Delta Bandsaw that from the Factory was made to do Wood. This same Model with an additional Gearbox allowed you to slow it down to under 200-FPS so It could do Steel as well.. The problem is that mine does not have this Gearbox and I want to use it to do Steel only.. From reading I find that in order to do Steel the Blade must be moving at under 200-FPS (Feet Per Second) - The current AC Motor runs at 1750-RPM and has a 2" inch OD pulley on it.. The Saw now has a heavy cast-iron 11" OD Pulley on it that replaced an 8" inch OD unit.. The "tires" or pulleys inside the housings that drive the blade are 14" inch OD and are on the same shaft as the 11" inch one.. I know that I need either a gearbox to slow down the Motor itself or a jack-shaft setup to slow it down.. or someone mentioned a "Variac" to change the speed of the AC Motor itself.. any thoughts as to what size I would need for pulleys? Or what ratio of Gearbox I could use on the Motor?

There is two Videos on this Saw that I have been restoring: #1


Understand that they do not show the 14" inch pulley just yet.. or a jack-shaft setup #2


Thanks in Advance to any offered HELP..

Rob in NH

[450donn]

By far the simplest is to get a variable frequency controller. But it might not be the cheapest method of getting variable speeds.
In essence if you double the diameter of the drive pulley you will half the RPM.

[berkelusa]

Thanks for the Reply on my thoughts Don..

I found a great calculator on:

OWWM - Calculate Band Saw Surface Feet per Minute (SFPM)

But it only shows you the FPS of the three sizes of pulleys not 4 if I went with a jackshaft setup.

Right now if I calculate mine there with the current measurements I have... 2" motor pulley x 11" drive pulley x 14" wheels = Calculated SFPM: 1,149

The thought is adding a gearbox that reduces the speed of the Motor.. Say with a 4:1 ratio box using the same pulleys.

My speed would be:

4:1 = 287 SFPM
5:1 = 233 SFPM
6:1 = 191 SFPM

Would this work or would the gearbox lag down the torque of the Motor?

Rob

[berkelusa]

The other thought was a "Variac" a Variable Transformer.. But how many amps should it be rated for? They average about $60.. Would the Amperage I need be the same rating as the Motor?

[450donn]

Never heard of a variable transformer. Multi tap transformer, yes. Used them all the time. A transformer by nature will take one voltage input and transform it to another voltage out. That would not work. Your motor is either 120VAC or 220VAC. With a Freq controller you would need to size it to the max amp rating for the motor as found on the rating plate.