After the epoxy has been thoroughly cured, the long piece of fiber may be removed by a simple cleave (see section on cleaving) and break from the point where it protrudes from the ferrule.

Grinding

The grinding/polishing fixture allows the ferrule tip to protrude beyond a flat reference surface, which provides a physical limit for grinding and polishing perpendicular to the fiber axis.

Wet papers are used for grinding and polishing. The coarse grinding process may use from 50 to 600 grit size. Also, dry papers are often used.

The initial grinding step removes excess fiber and epoxy from the ferrule tip. It also establishes a rough dimension for tip length.

A smooth level surface is needed for this operation. Very light pressure should be used for initial grinding until a flat surface develops on the end face. Best results can be obtained by gently moving the fixture in a small figure-8 pattern (about 1" loops) against the grinding surface. Grinding motion should be smooth and light. DO NOT PRESS HEAVILY.

After completing this step, the fixture and connector must be thoroughly rinsed in clean water to remove all coarse grit.

Polishing

This stage removes most of the coarse scratches from the grinding process. Wet papers, typically of 3-13 micron grit, are used. Use the same figure-8 motion with slightly more pressure - still not heavy. Upon completion, the ferrule end should appear satin. A fine scratch pattern will be seen under magnification. Again, the fixture and connector must be rinsed thoroughly.

The final step utilizes papers as fine as 0.3 micron. This is also a wet procedure. Apply the same firm, but not heavy pressure as in the prior polishing step.

Final polishing requires approximately 45 seconds to complete. A high-gloss surface should develop on plastic and stainless steel ferrules.

Ceramic-Tipped Connectors

Ceramic-tipped connectors afford more precision in fiber placement than similar metal types, but require modified polishing methods. Almost no ceramic is ground away because of the material's hardness, and it is possible to grind the fiber below the ceramic with a concave end surface, thereby reducing optical efficiency.

Manufacturers' methods minimize epoxy bead formation around the protruding fiber and use polishing devices which produce convex end surface on the fiber end. Follow manufacturer's directions.

Inspection

After polishing is completed, the fiber end should be inspected with a 30x to 200x microscope. This will show if the fiber is well centered and free from chips. The fiber end should be viewed under oblique light which will most clearly show scratches. If a major scratch appears across the center of the core area additional polishing may remove it. Scratches outside the core area are generally not considered critical.

When polishing is successfully completed, remove the fixture and position the strain relief in place behind the ferrule cap. When not in use, always protect connectors with dust caps.