Do yourself a big favor! Buy, borrow, beg..... a copy of Machinery's
Handbook.

I have the 25th edition, and on page 2282 is a section titled "Calculating
Diameters and Speeds of Pulleys".

Aside from the formula you want, it has diagrams showing the relationship of
the pulleys in the formula.
There is also extensive data on v-belt shapes, etc.

Good luck!
"Modat22" wrote in message
...
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.