Step pulleys: allow pulley to slide on shaft?

E

ernestrome

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Jan 25, 2006
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If I put a step pulley on my motor, driving a single pulley on a shaft between two Pillow blocks. Why can't I allow the shaft pulley to slide or float on the shaft to be parallel to the step pulley? Would the tension move the pulley to be in line?

Going to use a hinged motor mount to manage belt length differences.

If that is a bad idea, can I run my three step pulley to a two groove 2 inch pulley? Will the small offset be a problem? Talking about 1.5hp 1725rpm driving a belt grinder and disc mounted opposite ends of the shaft. I suppose I could add another 2 inch pulley beside my 2 groove for straight belt runs.
 
It's the pressure of the setscrew pressing against the key into the keyway that keeps the key in place.

If you have it all loose and floating, first your key will fall out and get lost.

Second, the keyway will start to wear out very quickly.

Why not just use a pair of step pulleys ?
 
12345678910 said:
It's the pressure of the setscrew pressing against the key into the keyway that keeps the key in place.

If you have it all loose and floating, first your key will fall out and get lost.

Second, the keyway will start to wear out very quickly.

Why not just use a pair of step pulleys ?
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I think that I'd prefer to have 1:1, 3:2 and 2:1 for my speed range as I have a 3.375 drive wheel.
 
Lock the pulleys solidly in place. The last thing you want is either one to be loose in any amount.

What you want its for the pivot shaft of the hinged motor plate to be a sliding rod. This way the motor will swing down to keep tension, and can be moved left or right to align he pulleys as desired. All you need to do is weld a piece of tubing/pipe with 3/4" ID on the edge of the motor plate and put a 3/4" rod through that. Attach the ends of the rod to the grinder frame with about 3" of extra room and the motor plate will swing and slide....... basically, a hinge with extra space between the end pieces and the center part.

BTW, the motor weight alone may not be enough to prevent belt slippage under grinding load ( especially when hogging). A bungee cord can help add more tension if needed.
 
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