{"id":513,"date":"2014-08-21T08:58:56","date_gmt":"2014-08-21T13:58:56","guid":{"rendered":"http:\/\/blog.misumiusa.com\/?p=513"},"modified":"2021-11-02T17:04:30","modified_gmt":"2021-11-02T22:04:30","slug":"timing-belts-pulleys-sizing-measurement","status":"publish","type":"post","link":"https:\/\/us.misumi-ec.com\/blog\/timing-belts-pulleys-sizing-measurement\/","title":{"rendered":"Sizing Timing Belts and Pulleys"},"content":{"rendered":"

Dear MISUMI Engineering Team:<\/strong><\/p>\n

We are building a machine that has several shafts driven by stepper motors<\/a>. These shafts need to be synchronized to each other, but at different speeds. We did some research and it looks like a timing belt<\/a> system will solve our problem, but we don\u2019t know how to proceed with selecting parts. Could you please provide some tips or recommendations?<\/strong><\/p>\n

Fred J.<\/strong><\/p>\n

Fred, thanks for your question. With any synchronization project, it’s all about the timing. Let’s start with a brief introduction on timing belts, pulleys, and how they work together.<\/p>\n

A timing belt<\/a> is used when the rotation of two different shafts need to be exactly linked. Normal power transmission<\/a> belts and pulleys are smooth, so the belt can occasionally slip off track (one shaft would be turning while the other remains still). On the other hand, timing belts and pulleys have teeth, which lock the rotation of the shafts and prevent misalignment. In a car, the timing belt links the engine crankshaft to the valve camshaft, thereby making sure that the valves open and close at the correct times. If that belt tears or breaks a tooth, the valves can open at the wrong time and ruin the engine.<\/p>\n

\u00a0\"timingTiming Belt and Pulley Image from <\/em>Photomacrography<\/em><\/a><\/p>\n

\u00a0There are a lot of different variables for belt sizing – width, number of teeth (pitch), material, etc. Each manufacturer will have different recommendations based on your project\u2019s specifications, taking into account shaft speeds, power transmission, environment, and other concerns. Take care not to needlessly oversize – a larger, stiffer belt can cause difficulties with smaller drive motors.<\/p>\n

As with any belt and pulley<\/a> system, you need to identify the rotation ratio between the shafts<\/a>. For instance, if shaft #1 needs to spin twice as fast as shaft #2, you would have a 2:1 ratio. Once this ratio is calculated, you can then select the pulleys. Looking at the number of teeth on the pulley, find two that match your desired ratio. Continuing with our example, if we had a 16-tooth pulley on shaft #1, we would need a 32-tooth pulley on shaft #2.<\/p>\n

\"belt Belt Length Image from <\/em>Nonstop Systems<\/a><\/em><\/p>\n

The next tricky part of the design is figuring out the belt length. You need to know the distance between the centers of the two shafts and the pitch diameters of the two pulleys, which is usually specified by the manufacturer. Most belt manufacturers will provide an online calculator for finding lengths of their belts, but the following formulas can be used to calculate belt length:<\/p>\n

\"calculating<\/p>\n

If you need an exact measurement, you can use the following formula:<\/p>\n

\"calculating<\/p>\n

where:<\/p>\n