Binary cam
A twin cam design where cams are slaved together for synchronization.
The binary cam is a pulley system design for compound bows. It functions as a modified twin cam setup, with each cam linked to the other by a loop of string. This differs from a standard twin cam system, where the bowstring ends are fixed directly to the bow limbs. In a typical twin cam setup, each cam rotates independently, relying on perfectly symmetrical force from the string and limb resistance. Over time, wear, string stretch, or aging can cause the system to lose tune, making the cams rotate out of sync. This results in the bowstring accelerating in two alternating directions when released, leading to unstable arrow flight. The binary cam solves this by "slaving" each cam to the other; one cam cannot rotate without the other moving equally, so they stay almost perfectly synchronized. Any small differences in rotation self-correct during the shot cycle. As a result, a binary cam bow never requires cam-timing adjustments, while a high-end twin cam bow might need such tuning every few months to maintain accuracy. Bowtech Archery pays royalties to Rex Darlington of Darton Archery for use of this design.
- Patent holder
- Craig Yehle
- Patent holder role
- director of research and development at Bowtech Archery
- Patent date
- December 11, 2007
- First model year equipped
- 2005
Lore & Background
The binary cam was developed by Craig Yehle, director of research and development at Bowtech Archery, who received a patent for the design on December 11, 2007. Bowtech began equipping its bows with the new cam design starting with the 2005 model year. The design overcomes the tendency of a typical twin cam system to 'lose tune' through wear and tear, string stretch, or general age, which causes the two cams to rotate out of sync and results in unsteady arrow flight. By slaving each cam to the other, the binary cam ensures that one cam cannot rotate without the direct equivalent action of the other, causing the two to rotate in near perfect synchronization and automatically correcting any possible differences in rotation as the shot cycle is completed. Bowtech pays Rex Darlington of Darton Archery royalties for use of this cam design.
Reader's Guide
The binary cam's significance lies in its elimination of the need for cam-timing tuning, a maintenance requirement that high-end twin cam equivalents might need as often as every few months to maintain critical accuracy. By mechanically linking the two cams via a loop of string, the design ensures that any potential differences in rotation self-correct during the shot cycle, providing consistent arrow flight without periodic adjustment. This represents a practical improvement over traditional twin cam systems, which rely on each cam rotating independently based solely on the force of the string and the resistance of the bow limbs being absolutely symmetrical—a condition that degrades over time. The binary cam's legacy is that of a design that addresses a fundamental weakness in twin cam compound bows, offering a more reliable and maintenance-free solution for archers seeking consistent performance.
Did You Know?
- The binary cam is a modified twin cam setup where each cam is slaved to the other via a loop of string.
- Craig Yehle, director of research and development at Bowtech Archery, received a patent for the binary cam on December 11, 2007.
- Bowtech started equipping its bows with the binary cam in the 2005 model year.
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