Circular Pitch
Arc Tooth Timing Belts

Our circular pitch arc tooth timing belts are dimensioned using pitch measured along the pitch circle of the mating pulley rather than a simple linear chord measurement — a distinction that matters specifically for rotary indexing tables, turntables, and circular positioning stages where the belt wraps a significant arc of a relatively small-diameter pulley. Getting this reference right prevents the cumulative angular error that a linear-pitch approximation introduces on tightly curved drives.

Material & Construction

Tooth spacing is calculated and molded relative to the pitch circle geometry of the target pulley diameter range, rather than assuming the flat, large-radius approximation valid for most linear drives. The belt body uses the same precision polyurethane and steel or fiberglass cord construction as our standard arc-tooth range, with tooth pitch verification performed specifically around representative small-diameter pulleys rather than on a flat measurement fixture.

Design & Performance

On a small-diameter pulley, the outer and inner tooth surfaces travel different effective distances per revolution; belts dimensioned only to a flat linear-pitch standard can accumulate small positioning errors over each full rotation on tightly curved drives. This series corrects for that geometry specifically, making it the more accurate choice for rotary tables, indexing turrets, and any drive where the belt wraps more than roughly 180° of a small pulley.

Manufacturing Excellence

Pitch accuracy is verified using a rotary pitch-measurement fixture that replicates actual pulley wrap geometry, rather than the flat pitch-line scanners used for standard linear belts — a distinction that matters specifically for this product line's target applications. Production batches are validated against ISO 5296 pitch tolerance using this rotary-specific method.

Customization & Flexibility

Offered in the AT10 and AT20 pitch range most common in rotary indexing applications, with belts engineered for specific pulley diameter ranges on request to further minimize rotational positioning error on your particular drive geometry.

Applications Across Industries

Our circular pitch arc tooth timing belts are deployed in:

• Rotary Indexing Tables – precise angular positioning drives.
• Turntables – camera, display, and inspection turntable drives.
• Circular Assembly Machines – rotary pallet and fixture indexing.
• Coordinate Measuring Machines – rotary axis positioning stages.
• Planetary Motion Systems – rotary-drive robotic and testing equipment.
• Optical Alignment Equipment – rotary stage positioning drives.

When your drive wraps a tight radius rather than running flat between two large pulleys, pitch geometry calculated for that reality — not approximated from it — is what keeps rotary positioning accurate. Pitch accuracy that accounts for the curve.