Splicing and Clamping Synchronous Belts

The question is often raised if it's possible to cut a synchronous (timing) belt into a custom length and splice the belt back together when a standard length does not fit the application. To answer this question: yes it can be done, but not very easily. Splicing two ends of a synchronous belt can be done when the belt is made with a particular type of polyurethane construction and additional polyurethane is used as "glue" to attach the ends of the belt. After this splicing process you can expect about 40% of the initial strength of the belt. This is because once you cut the tensile cord you've eliminated the strongest part of the belt. The spliced section is now the weak link of the belt, and like your co-ed softball team, you're only as strong as the weakest link. There are currently no processes to splice together a rubber synchronous belt.

Clamps are often used to attach two ends of a synchronous belt together. If this is done, the clamp must be contained on the belt span between the two pulleys. If a clamp ever attempts to ride over a pulley, catastrophic results will surely follow. If a clamp is used to attach two ends of a synchronous belt, a minimum of 6 teeth in mesh on each side of the belt is recommended. Anything below 6 teeth will lower the belts available working strength (6 teeth = tensile strength of belt), and premature belt failure from tooth shear is more likely to occur.