Machine Screw Diameters denominated with the industry Numeric Size system
Numeric Size denominations larger than #16 are uncommon.ĭiameters are based on ASME Coarse Thread Series (UNC/UNRC) and ASME Fine Thread Series (UNF/UNRF)Ĭ. Basic Major Diameters of industry Numeric Size-denominated screws: #14: A Number 14 size (sheet metal screws, Teks screws, wood screws)Ģ. #8: A Number 8 size (sheet metal screws, Teks screws, drywall screws, particle board screws, wood screws, U-drive screws) #6: A Number 6 size (sheet metal screws, Teks screws, drywall screws, particle board screws, wood screws, U-drive screws) These sizes were standardized based on sizes already commonly in use in the market.Īn industry Numeric Size, preceded by a # sign: These Numeric Sizes are shaft diameters (and inner diameters of some washers) that were standardized years ago by the American Society of Mechanical Engineers (ASME), American Society of Testing & Materials (ASTM), and other standards bodies. These industry Numeric Sizes run from #0 through #15, with #0 the smallest and #15 the largest. These do not show a number of threads-per-inch designation. Those parts that do not require matching with a mating item - screws or bolts that simply drill into or through a surface - are often denominated by industry Numeric Sizes preceded by a # sign. Parts that do not Require Matching with a Mating Item Note: The diameters of some smaller machine screws (though they may take a mating part), are denominated with the industry Numeric Size system described below. Same as for smaller parts.ġ-12: One inch shaft diameter, 12 threads per inchĢ-1/4-4-1/2: Two and one quarter inch shaft diameter, four and a half threads per inch The number following the hyphen is the number of threads per inch that is, the number of threads on the shaft itself, per inch of shaft length. The number 1 or number larger than one, or number one or number larger than one followed by a fraction, is the diameter of the shaft. The number following the hyphen is the number of threads per inch, that is, the number of threads on the shaft itself, per inch of shaft length.ġ/4-20: One quarter inch shaft diameter, 20 threads per inchģ/4-16: Three quarter inch shaft diameter, 16 threads per inchĪ number 1 or number larger than one, or number one or number larger than one followed by a fraction, then followed by a hyphen then a fraction or whole number: The fraction is the diameter of the shaft, in fraction of an inch. A fraction followed by a hyphen, followed by a number: Iameter of the washer before placing an order.ġ. The inner diameter of the ¾? washer will, in fact, be slightly larger than ¾? thereby enabling the washer to fit around the bolt.Ĭonsequently, when ordering a washer for a use other than matching it to a screw or a bolt, one should determine the actual inner For example, a ¾-16 bolt should be matched with a ¾ washer. It is important to note that when matching a washer with a screw or a bolt, the diameter of the shaft of the screw orīolt should be matched to the inner diameter of the washer. Screws and bolts that mate with a nut, as well as the nuts themselves, are denominated as such. Those parts that require matching with a mating item - screws or bolts with nuts or washers - have diameters that are denominated in actual inches or fractions thereof, followed by the number of threads per inch. Parts that Require Matching with a Mating Itemįor example: Screws or bolts that drill through nuts, washers Other size measurements, such as screw, bolts, pin length, the outer diameters of nuts & washers, etc., appear on the search result itself.Ī. You may search for your product based on diameter by selecting a measurement on the Size dropdown. The Size Dimension pertains to diameter of screws, bolts, & pins and inner diameter of nuts and washers.