![]() ![]() When the edges of the beam and blade are parallel, a small mark on the swivel plate coincides with the zero line on the graduated dial. The bevel protractor consists of a beam, a graduated dial, and a blade which is connected to a swivel plate (with Vernier scale) by a thumb nut and clamp. It reads to 5 arcminutes (5′ or 1 / 12°) and can measure angles from 0° to 360°. The bevel protractor is used to establish and test angles to very close tolerances. Universal bevel protractors are also used by toolmakers as they measure angles by mechanical contact they are classed as mechanical protractors. It has wide application in architectural and mechanical drawing, although its use is decreasing with the availability of modern drawing software or CAD. Sometimes Vernier scales are attached to give more precise readings. ( September 2020) ( Learn how and when to remove this template message)Ī half-circle bevel protractor A universal bevel protractor.Ī bevel protractor is a graduated circular protractor with one pivoted arm used for measuring or marking off angles. There might be a discussion about this on the talk page. This article may be confusing or unclear to readers. A protractor divided in centiturns is normally called a " percentage protractor". Some precision protractors further divide degrees into arcminutes. Most protractors are divided into 180 equal parts. Radian-scale protractors measure angles in radians. Most protractors measure angles in degrees (°). More advanced protractors, such as the bevel protractor, have one or two swinging arms, which can be used to help measure the angle. Some protractors are simple half-discs or full circles. Protractor A half-circle protractor marked in degrees (180°).Ī protractor is a measuring instrument, typically made of transparent plastic or glass, for measuring angles. The first known description of a goniometer, based on the astrolabe, was by Gemma Frisius in 1538. The protractor is a commonly used type in the fields of mechanics, engineering, and geometry. The term goniometry derives from two Greek words, γωνία ( gōnía) ' angle' and μέτρον ( métron) ' measure'. Goniometer made by Develey le Jeune in Lausanne, late 18th–early 19th centuryĪ goniometer is an instrument that either measures an angle or allows an object to be rotated to a precise angular position. This coordinate value describes the southwest corner of the 10- meter square in which you’re target is located.For other uses, see Goniometer (disambiguation). Then, read the values indicated on the plotter, in this case 89300478. You slide it along that line until the plotter’s vertical axis lines up with the X. Using your plotter to locate your target within a 10-meter square, you line up the plotter’s horizontal axis with the 04 northing line. Your target is therefore located in the 1,000-meter square identified as 8904. The closest northing line to the south of your target is 04. The closest easting line to the west of your target’s location is 89. Once again, start at the bottom left of the map, and READ RIGHT UP. Reading the plotter, your coordinates are 88240450 Plot Map Coordinates - Plotting Point B To do so, place the horizontal axis of the 1:25,000-scale plotter on the 04 northing line, as shown, moving it until the vertical axis lines up with the targeted X. So, now you’ve located your target within a one kilometer square, now use the plotter to locate it within a 10-meter square. The intersection of these two lines (8804) puts you at the southwest corner of the 1,000 meter square containing your target location. Next, go up that easting line until you come to the closest northing line to the south of your target location, in this case 04. Remember, the coordinate itself does not pinpoint the target, but simply describes the southwest corner of the 10-meter square in which the target lies. In this case, our plotted coordinates will locate our targets within a 10-meter square. We’ll plot three targeted points: A, B, and C. Once you understand the UTM and MGRS grid systems, and know how to use one plotter, you can pretty easily figure out how to use most other plotters. There are civilian plotters available in other scales, such as 1:24,000. In these examples, we’ll be using a “blank map” with a 1:25,000 grid. ![]() This tool is designed to work with the military’s 1:25,000-scale maps, as well as the 1:50,000 and 1:100,000 maps. Let's see now how to plot map coordinates using a military protractor. Announcement: My online Land Navigation course includes four hours of video instruction, and two downloadable PDF books, all for about the same price as a typical paperback book. ![]()
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