On Wed, 24 Dec 2003 22:36:55 GMT, (Roy) wrote:
On Wed, 24 Dec 2003 16:13:14 GMT, (Roy) wrote:

===In the process of making my 3 wheel bandsaw. I am wanting to use a DC
===motor of 1 1/2 hp with a speed controller, but would like to add a
snip
I forgot, the wheels are 12 inches in diameter that I cast for this
saw as I could not swing larger and machine them in my lathe.

Ok, so the blade will move 3.14 feet for every rotation of the drive
wheel (pi * diameter). With a motor speed of 5120 RPM, that's a
blade speed of 16,077 feet per minute. That's *way* too fast even
for sawing wood.

Typically for wood you'd want a blade speed of about 2000 FPM,
or roughly an 8:1 speed reduction. For cutting steel, you want a
blade speed of about 150-200 FPM, so you need a speed reduction
of about 100 to 1.

Suppose you use a jackshaft and two sets of pulleys, each a 6:1
ratio, which will give a total of 36:1 speed reduction. Then you can
use the electronic speed control to give the remaining 3:1 reduction
for a total of 108:1. That should be reasonable, and still lets you
speed up about 3x for cutting non-ferrous metals.

For cutting wood, you could swap one of the '1' pulleys for a '6'
pulley. That'd give a 6:6 or 1:1 ratio for that set, leaving you with
just the basic 6:1 reduction provided by the other set. The electronic
speed control could then drop the speed the remaining amount to
hit 2,000 FPM for cutting wood.

Gary