Fingertech S3M Timing Belt

• Positive lock under load: Toothed S3M profile eliminates belt slip on drive and weapon systems
• 39 sizes available: 120mm (40T) to 408mm (136T) — design your robot first, find your belt after
• 55 ratio combinations: Ten compatible FingerTech S3M pulleys yield 55 unique pulley pairings
• Fiberglass-reinforced construction: Chloroprene rubber with fiberglass core for durability under combat loads
• 360 Newton max load rating: Built for the sustained tension of competitive robot drivetrains
• Universal compatibility: Works with any 3mm pitch pulley 4mm wide or less
• Lightweight: 1–4g depending on size — negligible weight penalty for any build

Specifications

Available Sizes

Frequently Asked Questions

How do I know which belt size to order?

Use the FingerTech Pulley-Belt Distance Calculator — it's the fastest way to find the right belt. Enter your pulley sizes and desired center-to-center distance and it will tell you which belt to use. Or enter a belt size and it will tell you how far apart the pulleys will sit. With 39 sizes available, there's almost always a belt that fits your layout.

What pulleys are compatible with these belts?

Any 3mm pitch pulley that is 4mm wide or less will work. FingerTech S3M pulleys are the natural pairing and are available in ten sizes on ItGresa. Third-party 3mm pitch pulleys are also compatible as long as the width doesn't exceed 4mm.

Why use a timing belt instead of an O-ring or round belt?

O-rings and round belts rely on friction and will slip under tension — especially under the sudden loads a combat robot generates. Timing belts have teeth that mechanically engage the pulley, making slip essentially impossible when the belt is properly tensioned. For drive and weapon systems where consistent power transfer matters, timing belts are the right choice.

Are these belts sold individually or in multipacks?

These belts are sold individually. Each listing is for one belt of the selected size.

Can I use these belts for both drive and weapon systems?

Yes. The S3M profile and 360 Newton max load rating make these belts suitable for both drive and weapon applications at the antweight and beetleweight class levels. Match your belt size to your center-to-center distance using the calculator and you're set.

What does "S3M" mean?

S3M is a belt profile designation. The "3" refers to the 3mm pitch — the distance between tooth centers. The "S" indicates a curvilinear tooth profile, which provides better load distribution and reduced wear compared to older trapezoidal tooth profiles. S3M is a widely used standard in robotics and light industrial applications, which is why compatible pulleys are readily available from multiple sources.