Center to Center with belts

[sanddrag]

I used XL timing belts and pulleys from McMaster and the SDP-SI calculator and I would call it a very loose fit, but it never skipped. I would have liked the fit to have much less slop though.

[DELurker]

The industrial answer is to make the perimeter that encompasses the OD of each pulley and the tangents to those edges equal to the inner perimeter of the belt, so that it fits over all pulleys at the same time. Then, either cam one shaft into location (ie - slide) or use a cam-style idler roller for belt tensioning (cam followers work great for this).

Of course, if you don't want to have a separate tensioner and you want the shafts to be fixed in place, you can have one of the pulleys have either no flange or a removable flange. After all, you typically only need flanges on every other pulley.

A really good resource for timing belt information is http://www.martinsprocket.com/2001/SecK.pdf#J2
It has center-to-center charts, rules of thumb, engineering calculations, and design criteria.

[iyermihir]

Originally Posted by DELurker

Of course, if you don't want to have a separate tensioner and you want the shafts to be fixed in place, you can have one of the pulleys have either no flange or a removable flange. After all, you typically only need flanges on every other pulley.

We had fixed flanges on all of our pulleys this year and it worked fine. The trick is to put the belt on the pulleys before putting the pulleys on the shafts. Keep the pulleys in the same plane as you slide them onto the shafts and it will work fine.

-Mihir Iyer