You can convert a round hole to a square hole using precision filing, broaching, or rotary broaching techniques, ensuring careful alignment and minimal stress on the fiber.

Hand Filing Method

For small-scale or delicate applications like pigtail fibers, hand filing is a precise and controlled method. Begin by marking the desired square outline over the round hole using layout ink and a scribe. Secure the workpiece in a vice. Use a three-square file to create notches at each corner, then switch to a square file to remove material along the edges. Finally, a pillar file can refine the corners to exact dimensions, working one corner at a time to avoid damaging the fiber or surrounding material .

Broaching and Shaping

Broaching involves using a shaped tool to gradually cut the round hole into a square profile. You can create a custom broach from hardened steel, heat-treat it, and carefully push or pull it through the hole. This method is suitable for slightly larger holes or when multiple identical square holes are needed .

Rotary Broaching

Rotary broaching is a highly precise technique often used in machining small connectors. A rotary broach tool is inserted into the round hole and rotated under pressure, cutting the square shape in a single pass. This method is efficient and produces clean edges, making it ideal for high-precision applications like fiber optic connectors .

Considerations for Pigtail Fibers

• Hole size tolerance: Ensure the original round hole is slightly larger than the diagonal of the square pin to allow a snug fit without stressing the fiber .
• Material handling: Avoid excessive force to prevent cracking or chipping the fiber housing.
• Alignment: Keep the square shape centered to maintain proper connector alignment and optical performance.
• Finishing: Smooth edges with fine files or polishing tools to prevent mechanical stress or interference during insertion. By combining careful marking, controlled material removal, and appropriate tooling, a round hole can be successfully converted to a square hole while maintaining the integrity of the pigtail fiber and its connector assembly .