<p>Wire bow in diamond wire sawing leads to trajectory deviation, which significantly reduces the geometric accuracy of hard and brittle materials. Existing vision-based approaches focus on monitoring the slicing process and typically rely on high-speed cameras. However, few practical solutions exist for profile cutting, where the wire bow spatially varies in real time. This study proposes a low-cost, vision-based servo feed control system for regulating the wire-bow angle in a reciprocating single-wire saw. A standard camera is used for straight cutting, while two cameras independently operate for profile cutting. An event-triggered pause/resume strategy based on dual wire-bow-angle thresholds of 0.5° (lower) and 1.0° (upper) is implemented using a National Instruments LabVIEW-based host computer and an embedded controller. The system successfully maintains the upper wire-bow angle within the predefined range throughout the cutting trials. Comparative experiments on soda-lime silicate glass for straight and octagonal profiles are then conducted. The obtained results show that in straight cutting, the sawn length and surface flatness accuracy are markedly increased compared with the conventional process without vision-servo control. For octagonal cutting, the mean errors of opposite-side distance decreased by 18.4%, and the standard deviations were lower by 63.5%. Additionally, the angular dispersion of adjacent-edge was reduced by 80.2%. This vision-based strategy effectively controls the spatial wire bow using economical hardware and logic, providing a practical pathway toward closed-loop control in straight and profile cutting of hard-brittle materials.</p>