Japan has a JIS metric screw thread standard that largely follows the ISO, but with some differences in pitch and head sizes. Oberg, Erik; Jones, Franklin D.; Horton, Holbrook L.; Ryffel, Henry H. (2000), Machinery's Handbook (26thed.), New York: Industrial Press Inc., ISBN 0-8311-2635-3.

This article may be too technical for most readers to understand. Please help improve it to make it understandable to non-experts, without removing the technical details. ( December 2020) ( Learn how and when to remove this template message) We’ll be explaining each definition of these to help you read our metric screw size chart. 1. Screw Diameter There is a huge variety of types of screws and bolts available in the market that are available in different drive types, head styles, materials, sizes and thread pitch. They can be used with a range of complementary nuts and washers to prevent loosening once in place. Some of our most popular fixing categories include: Don’t get it confused with the US gauge. Just because they’re both written as the first numbers in callouts, doesn’t mean that they’re the same thing.In the examples shown above, the M6 is a 6mm wide screw (at the threaded part, not the head) and the M8 is 8mm wide. Other Acronyms and Abbreviations used to Describe Screws Hex bolts – have a hexagonal shaped head and can have a full or partially threaded length, used with a tapped hole or interior nut thread. There are a range of acronyms and letters that you often find on screw boxes or in their online descriptions. Here is a summary of the most common, and what they mean: The "M" designation for metric screws indicates the nominal outer diameter of the screw thread, in millimetres. This is also referred to as the "major" diameter in the information below. It indicates the diameter of smooth-walled hole that a male thread (e.g. on a bolt) will pass through easily to connect to an internally threaded component (e.g. a nut) on the other side. That is, an M6 screw has a nominal outer diameter of 6 millimetres and will therefore be a well-located, co-axial fit in a hole drilled to 6mm diameter. Head diameter in sixteenths is an inch X 2 ) – 2 = Gauge. E.g. 5/16 head times two equals 10, minus two equals 8. The Gauge is 8.

Typical examples of uses for grub screws might include any situation where one object or component needs to clamp to another tightly via friction, but where protruding parts of the fastener would interfere with smooth functioning of the items in question. Grub screws for this purpose are especially widely used in architectural ironmongery, and are a very common feature found wherever door handles are attached to spindle shafts.A coarse screw is a screw with a low number of threads along the screw. While a fine screw has a high number of threads. Tables of the derived dimensions for screw diameters and pitches defined in ISO 261 are given in ISO 724. Set screws often do feature a head - very likely a hex fitting - but without a threadless section immediately below it (again, this is different to the length of unthreaded shank you’d typically find on a standard bolt). Because they often feature no protruding screw head in the traditional sense, true grub screws tend to be driven by means of a sunken internal recess at what is still generally referred to as the ‘head end’.