Modat22 wrote:
I'm cobbling together a DIY band saw and I'm trying to size Pulleys.

Band wheels are 15 inch diameter.

I need around 75 fpm speed on the band (I'm guessing on this, waiting
on band specifications for real number)

I will have a double pulley directly connected to one of the band
wheels probably being 12 inch diameter

Motor will be 1800 rpm 10 hp gas No idea on the motor pulley size.

I could really use a formula that I could play with editing the sizes
of the wheels and pulleys.

Thanks folks.

P.S. on a different topic I going to try a few welding classes. It is
cheaper in the long run and in instruction.

75 feet/min = 900 inches/min

Pulley circumference = pi * 15 = 3.142 * 15 = 47 inches (approximately)

So each minute you need the pulleys to rotate 900/47 = 19 times

So pulley rotational speed = 19 rpm

To drive the pulleys from an engine running at 1800 rpm you're going to
need a reduction of around 100:1. This will probably require a three
stage belt drive with a reduction of somewhere between 4:1 and 5:1 per
stage. You might want to look at using an automobile gearbox to achieve
part of this reduction, or a worm and wheel gearbox if you can find a
suitable one. I recall seeing pictures of a saw driven by an automobile
engine and gearbox in a magazine once.

Hope this helps,

Chris