In the photos below, see if you can identify what is wrong with the application in the picture.
Those are synchronous sprockets, with a V-belt installed to transmit power! An application engineer was visiting a customer site and ran across this "creative" use of mismatched components. Best guess is that originally the V-belt was installed because a replacement synchronous belt wasn't on hand, and it worked "good enough" that they never went back and used the proper components.
Obviously - NOT RECOMMENDED!
Many years ago, a farmer called the Product Application department with a question about what nail size he should use - 8d, 10d - he didn't know for sure. A confused application engineer asked him what he was talking about - you don't use nails on a belt drive. The farmer replied that he was rebuilding a windmill to get water to his livestock, and all he wanted to know was what size nails the synchronous belt needed to run on. Even more confused, the engineer pressed for more details....turns out that the farmer was planning on making his own sprockets by welding nails between two steel plates and needed to know the nail size that would best fit in the belt teeth to act as the sprocket teeth!
Sometimes you learn what to do correctly by seeing things that are done incorrectly.....