metal versus plastic pulleys

[margni74]

I need to gear down a couple of my motors... I'm specifically looking at getting some of the polycarbonate timing pulleys from SDP/SI.

Are these going to shred themselves into pieces?

The metal pulleys are about 4x more expensive.

[Asmordo]

Hi! (This is my first post. So I guess I'm not a silent lurker anymore ^_^; )
It's my uneducated bet that polycarbon pulleys will stand quite a beating. At what speeds would you be using them at? It would be less likely that a pulley of metal would shatter when going at 20000rpm. But we all have seen what happens to cd's that's also made of polycarbon...
Just kidding though. I have no idea if something similar could ever happen to a pulley made of polycarbon. I'm just venting my opinion a bit. I hope you don't mind!?
But as I'm also planning to buy some pulleys in a couple of months, and they are probably going to be metal, it feels strange to recommenced you buying the ones of polycarbon. The reason why I will buy metal is probably because that's what most machines use that I have seen, so I'm used to the sight (maybe a bad thing!?) Most were old though. Maybe it's more common now a days with polycarbon and other more - in my opinion - exotic materials?! Maybe someone knows.

--edit--
I saw now when I reread your post that you were using the pulleys to gear down your motors. Sorry, I must have missed it. Then it would probably be safer to use the polycarbon pulleys I guess. But I would still go for the metal if it were me. (I love to use more money than I need just to be safe)

[dertsap]

you'd shred the belts before you do any damage to the pullies

[johnmac]

The only problem I have seen with nonmetallic gears and pulleys are with set screws. its easy to over tighten, and if they don't crack at the time, they do over time.

John

[margni74]

Thanks for the replies... i went with polycarbonate.. They seem to be doing the trick so far.