step pulley material?

[curtis rosche]

im trying to figure out what im going to do for a pulley for my new lathe, its will be a step pulley, but large step pulley can be very pricey, so im looking at making one. what materials will handle the two horsepower motor? and will be easy to machine. i have access to metal lathes and a an aluminum and bronze foundry here at school. i was thinking either one of those metals, or maybe plastic or maybe wood, im not sure what would work.

[Dennis Ford]

Aluminum would be my choice for easy to machine, bronze would be good but expensive.

[John G. Lopez]

I found a surplus metal guy in my area & bought a used alloy ? 2 step for under $5 .
He had a bin full of them.
Even with shipping it might prove less expensive in the long run than making one.
I'd go with a hard, dense and stable timber if I was making one.
Perhaps oak, osage orange, or lignum vitae if you can get it.
http://www.ksurplus.com/

[John G. Lopez]

These materials should also be considered...
cheap plastics such as Polypropylene, Polyethylene or PVC .

[Dennis Puskar]

I would use Aluminum

[David Reed]

Aluminum for a variety of reasons, mostly strength, stability, ease of machinability and cost.
But, consider the use of an intermediate jack-shaft if you want major speed reduction. If the motor is mounted and belted correctly you can readily change from simple step up, step down using the step pulleys to large speed reduction using the jack-shaft which you may really want if turning large unbalanced forms. You can get 10:1 reduction with really large step pulleys but not really practical.

[curtis rosche]

i will look into the jack shaft in the future, but for now i think i should be able to get by with out one since i can only put a 14 inch peice on it,

[Scott Lux]

since i can only put a 14 inch peice on it,

When you say things like this, you frighten most of us. Don't underestimate the forces involved in something that size.

[curtis rosche]

whats the lowest speed you would need for a 14 inch piece?

[Scott Lux]

My lathe isn't capable of 14", so I can't say from experience.
NOVA suggests 200 RPM for roughing something that size and 600 for general turning. The old rule of thumb (diameter X RPM between 6000 and 9000) puts the range between 400 and 650.
I'd be willing to bet any 14" chunk of wood will be out of balance until you've turned away a lot of the mass. Slower is better here. See if you can get your lathe down to 200-300 RPM.