I just picked up the HF 14" Bandsaw with 4 speeds. I am trying to figure
out the spindle RPM at each of the different belt positions. The manual
lists exactly what they are, but I am trying to figure out how they
I know how to figure out the final RPM when dealing with a drive pulley and
a driven pulley. I also thought I knew how to figure out the RPM of a 3
pulley setup, but I can not seem to come up with the same numbers in the
Here are the numbers. (pulleys are measured at their large diameter)
Motor: 1720 RPM
Motor Pulley Diam: 1.75" (this has 3 other diameters, but I am only listing
Middle Pulley Diam: 5.3" (This is where the motor belt attaches)
Middle Pulley Diam: 1.89" (This is where the spindle pulley belt attaches)
Spindle Pulley: 5.97"
I figure the ratio from the motor pulley to the middle pulley is 5.3 / 1.75
The ratio from the middle pulley to the spindle pulley is: 5.97 /
I multiply my two ratios 3.03 * 3.16 = 9.57.
Then I divide the motor RPM by the calculated ratio: 1720 / 9.57 = 180 RPM
The manual states that in this configuration, the Spindle Speed is 600 RPM.
It also states that in this configuration the Blade Speed is 625.1 FPM.
Since the diameter of the bandsaw tires are 13.75", this makes sense if I
use my calculated 180 RPM as the spindle speed.
180 * 13.75" *
3.14 / 12" = 647 FPM. This is close to what is stated.
So where do they get this Spindle Speed of 600 RPM?