Types of Rules Measuring system, Rulers, Calipers and Gauges Teacher: Tadros Student: Li Zhi Module: #12 – Taking and Interpreting Measurements Contents Measuring System .......................................................................................................................................................... 1 Imperial System ............................................................................................................................................... 1 Metric System ................................................................................................................................................... 1 Rulers ................................................................................................................................................................................... 2 Pocket Rule ........................................................................................................................................................ 2 Narrow Rule ....................................................................................................................................................... 2 Flexible Rule ...................................................................................................................................................... 2 Narrow Rule With Holder ........................................................................................................................... 3 Hook Rule With Fixed Hook ...................................................................................................................... 3 Micro Calipers ................................................................................................................................................................... 4 Operating Principles Of A Micrometer ................................................................................................ 4 Components Of A Micrometer ................................................................................................................. 5 Precisions Of Micrometers ......................................................................................................................... 6 Different Types Of Micrometers ............................................................................................................. 6 Vernier Calipers ................................................................................................................................................................ 7 Diagram of Vernier calipers. ...................................................................................................................... 7 Different Types Of Calipers ........................................................................................................................ 8 - 1 - Gauges ............................................................................................................................................................................. 11 Plug Gauge ...................................................................................................................................................... 11 Ring Gauge ...................................................................................................................................................... 11 Snap Gauge ..................................................................................................................................................... 12 Gauge Blocks .................................................................................................................................................. 12 A (Go)-(No Go) Thread Snap Gauge ................................................................................................... 13 Dial Indicator .................................................................................................................................................. 13 Electronic Gauge ........................................................................................................................................... 14 Optical Comparator .................................................................................................................................... 14 Optical Flats .................................................................................................................................................... 15 Thickness (Feeler) Gauge ......................................................................................................................... 15 Screw Pitch Gauge ....................................................................................................................................... 16 Drill Rod ............................................................................................................................................................ 16 Fillet And Radius Gauges ......................................................................................................................... 17 Telescoping Gauges .................................................................................................................................... 17 Small Hole Gauge ........................................................................................................................................ 18 Surface Gauges .............................................................................................................................................. 18 - 2 - Measuring System Imperial System Imperial measuring uses either fractional inch (graduations) system or decimal inch system: 1. Fractional Inch: Fractional Rulers have graduations or marks based on fractions, for example 1/2", 1/4" 1/8", 1/16", etc. 2. Decimal Inch: Decimal Rulers have graduations or marks which are based on the decimal system such as 0.5, 0.25, 0.1, 0.05, etc. The drawing on the right side shows a fractional ruler with a smallest graduation of 1/32" (indicated with a scale legend of 32nds beside the scale) and describes how to measure each fraction of an inch. Metric System Metric Rulers may have any combination of: Meters - abbreviated as m, Centimeters - abbreviated as cm, Millimeters - abbreviated as mm. In the drawing we show various options for cm and mm and how to correctly read the ruler; remember 10mm = 1cm and 100cm = 1m. - 1 - Rulers Pocket Rule An accurate pocket rule most commonly used fractions (8ths, 16ths, 32nds, and 64ths) is invaluable in woodworking. The typical one (6" x 3/4") is easy to read, with a satin finish, milled edges and tips, and a nice extra — it is graduated (in 32nds) on the ends as well. Narrow Rule A narrow rule is usually made from steel, and is very widely used in the schools and offices. The typical stainless steel narrow ruler is 100~300mm long; 13 mm wide; 0.5 mm thick graduated in 1 mm increments on the top edge and in 0.5mm increments on the bottom edge. Flexible Rule A flexible ruler is usually rubber or plastic coated with a metal "backbone", which can be smoothly shaped to follow a desired curve and allows drawing a smooth line between initial reference points. Sometimes a spline is temporarily held in position with small weights. - 2 - Narrow Rule With Holder A narrow rule with holder can be used as handy for depth gages. The typical rule holder holds any rule or combination square blade from 3/4 - 1-9/16 in wide in an upright position for use in transferring measurements with surface gauges. Hook Rule With Fixed Hook Hook rule permits a quick registration against the edge of a work piece, each of these rules has a hardened steel hook at one end. The hook rules have scales accurately zeroed to the hooks on one face for measuring from an edge and zeroed to the square end on the other for use as a regular rule and for depth measurements. - 3 - Micrometer Calipers A micrometer, sometimes known as a micrometer screw gauge, is a device incorporating a calibrated screw widely used for accurate measurement of components[1] in mechanical engineering and machining as well as most mechanical trades, along with other metrological instruments such as dial, Vernier, and digital calipers. Micrometers are usually, but not always, in the form of calipers (opposing ends joined by a frame). The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil. The spindle is moved by turning the ratchet knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil. Micrometers use the screw to transform small distances (that are too small to measure directly) into large rotations of the screw that are big enough to read from a scale. The accuracy of a micrometer derives from the accuracy of the thread-forms that are central to the core of its design. In some cases it is a differential screw. Operating Principles Of A Micrometer 1. The amount of rotation of an accurately made screw can be directly and precisely correlated to a certain amount of axial movement (and vice versa), through the constant known as the screw's lead. A screw's lead is the distance it moves forward axially with one complete turn (360°). (In most threads [that is, in all single-start threads], lead and pitch refer to essentially the same concept.) 2. With an appropriate lead and major diameter of the screw, a given amount of axial movement will be amplified in the resulting circumferential