A riffler is a small to medium-sized, file-like tool used for shaping and smoothing various materials like wood, metals, stone, and composites. Rifflers are most commonly made of steel with a handle made of metal or wood and teeth that can vary in number, density, and size. This tool is generally coarser in texture than a file and is used for a variety of crafts, including woodworking, stone sculpting, metalworking, model building, jewelery making and die-making. It can also be referred to as a riffler rasp, if the teeth are set in wider rows and are coarse and pointy, or a riffler file, if it has long lines of smaller teeth. Rifflers come in a variety of shapes and profiles, and are commonly used to finish and shape surfaces in areas that are hard to reach or of unusual shape.
A riffler can have teeth that are fine, medium, or coarse. The size of the teeth is also called "grain," and the various grains are referred to by numbers. #1 grain is the coarsest, meaning the teeth are large and set wide apart. A higher number for the grain means it is finer, with smaller teeth set closer together. Most riffler tools are made of steel, because of its hardness and durability. There are also electroplated diamond rifflers, commonly recommended for shaping stone and often specifically used for detailed stone-sculpting work.
Many rifflers are double-ended, meaning they have teeth cut into both ends of the tool, essentially providing two tools in one. The two ends are usually of different shape and grain and complement each other so that a craftsman working on a project can flip the riffler around instead of having to get another tool. In woodworking, there are specific styles of double-ended rifflers that are traditional and have been made by toolmakers for more than a century.
In spite of the shared term, rotary rifflers are very different from regular rifflers. A rotary riffler is a device used to accurately generate smaller, representative sub-samples from a large sample of a powdered or granular substance. These devices use vibration and rotation to mix the original material and then divide it into smaller amounts that contain all the characteristics of the original material. They can be used to test and analyze various properties like particle size, density and composition of, for example, geological samples, pigments, soils, and pharmaceuticals. They are commonly used for compositional analysis of ore samples, a process also known as metallurgical assay.