Understanding Metric Fastener s. Length is measured the same as inch fasteners, except in millimeters. For button, cheese, hex, pan, socket and low socket heads, measure length from under the head. For flat heads, length includes head height. Measure oval heads from the largest diameter point—where the dome top meets the conical bearing surface— Dec 17, 1998 ISO metric screw thread. They were one of the first international standards agreed when hereanization for Standardization was set up in 1947.  The M designation for metric screws indicates the nominal outer diameter of the screw, in millimeters (e.g., an M6 screw has a nominal outer diameter of 6 millimeters). Fastener Identification Chart; Finished Hex Bolt Dimensions ; Finished Hex Nut Dimensions ; Hardness Conversion Chart; Heavy Hex Bolt Dimensions ; Heavy Hex Head Cap Screw Dimensions ; Heavy Hex Nut Dimensions ; Hot Dipped Galvanizing; Imperial to Metric Conversions; Metric to Imperial Conversions; Metric Hex Bolt Dimensions ;
Metric Screw Thread Chart Metric Tap Size Tap Drill (Inches) Clearance Drill (Inches) . Outside Diameter of Screws mm inch mm inch 1.6 0.063 8.0 0.315 1.8 0.071 10 0.394 . The clearance drill sizes listed are heremonly used sizes . Metric Fastener Reference Charts including DIN and ISO Designations, Common Metric Sizes , Metric vs. Inch Sizes , Fastener Sizes in Inches, Pitch vs. Threads per Inch, Millimeters to Inch Conversion. External Metric Thread Table Chart and Fastener Sizes M1.6 - M18. Do not use these values for standard metric internal thread design. All units in mm. These are the M Profile limiting Dimensionings. Where: H = P ( 3 1/2 / 2 ) = 0.866025 P or 0.125H = 0.108253P Engineering Slide Chart ANSI Screw Hardware Selector.
Metric Fasteners . Machine Screws ISO metric machine screws are limited to four different head shapes: countersunk, raised countersunk, panhead, and cheesehead.. All head dimensions are directly related to the basic screw diameter as follows: A metric machine screw is a straight shank fastener with a metric thread pitch designed to go through a hole or nut that is pre- tapped to form a mating thread for the screw. Applications/ Advantages. Machine screws form a fastening superior in strength to spaced thread screws.