# Rockwell scroll saw



## Jaco (26 Oct 2004)

I am busy rebuilding an old scroll saw.
Got a motor that runs at 1450rpm.
Now need a pulley on the motor and two pulleys on the saw.
How do i calculate the sizes of the 3 pulleys to get the right saw speed?
The saw must run at 800rpm and 1275rpm.


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## Johnboy (26 Oct 2004)

The circumference of a pulley is directly proportional to the diameter. In other words if the pully size doubles then the circumference doubles. So to reduce the speed by half the pulley on the saw needs to be twice as big as the one one the motor.

For the speeds you quote if the pulley on the motor is 100mm then the saw needs pulleys of 114mm and 181mm.

John


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## Jaco (28 Oct 2004)

Thanks very much John.


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