Union Butterfield 4533 High-Speed Steel Chucking Reamer, Straight Flute, Round Shank, Uncoated (Bright), 1/4 inch
The Union Butterfield 4533 high-speed steel straight flute chucking reamer (also called a machine reamer) is an uncoated (bright) round shank tool with a 45-degree bevel lead, commonly used for general-purpose reaming of uninterrupted cuts. This tool is often used in a drill press, screw machine or lathe. Straight flute reamers are useful for uninterrupted cuts in general-purpose applications. They make small, circular, and precise enlargements to through holes (extending through the workpiece) and blind holes (with only one opening). They can be used on a wide variety of materials including cast iron, aluminum, and tool steel. High-speed steel is a general-purpose steel for cutting tools and is compatible with many metalworking materials. It is often lower in price than other cutting tool substrates. Like most non-tapered chucking reamers, the Union Butterfield 4533 has a 45-degree bevel at the cutting tip that facilitates entry to a pre-drilled hole.In the Union Butterfield 4533 series, reamers 0.0400 to 0.1540” diameter have four flutes  reamers 0.1562 to 0.5312” diameter have six flutes, and reamers 0.5469 to 1.5000” diameter have eight flutes. Tolerances for reamers up to 0.5000” are +0.0002 to -0.0000”; larger than 0.5000” and up to 0.7500” are +0.0003 to -0.0000”, and larger than 0.7500” up to 1.5000” are +0.0004 to -0.0000”. There is an exception for reamers that are dowel-pin sized, in which cases tolerances are +0.0000 to -0.0002”.Reamers are used to finish existing holes. When holes are created using common applications such as  drilling or punching, they often have minute imperfections. Their roundness may be flawed, or their diameters may be slightly smaller than required. Reamers are made to exacting tolerances, so they can correct such errors and create precisely round holes with exact dimensions. Reaming is often used before tapping screw threads.Union Butterfield manufactures a range of machine tools, including drills, reamers, taps, dies, end mills, and made-to-order items. Formed in 1913, the company is a subsidiary of Sandvik, a Swedish machine tool corporation. Union Butterfield offices and manufacturing facilities are located in the United States.