![]() The end of the flexible tape itself is shortened to allow for the hook. However, in the field you will often need approximate measurements and the only measuring tool at hand will be a measuring tape.Ī steel pocket tape measure has a movable hook on the end that allows accurate measuring both when butted against a surface or when hooked on the end of an object (Figure 9). If you use the scale of the drawing, it will be simple to read off the measurements. Measuring plans is not accurate enough for measuring materials for cutting and installation purposes. ![]() In such cases, 10% is usually added for cut-off and waste allowance. When accuracy is not required and approximate dimensions are adequate, measuring plans is a quick method of taking off material for estimating the cost of a job. Details, however, often require more exactness and usually contain any needed dimensions. Detail drawings permit more exactness because they are proportionately larger. For example, if the scale of a drawing is 1/8 " = 1 '-0 ", an error of 1/32 " in measuring the plan amounts to 3 " of error in the object measured. ![]() The scale of the drawing and your accuracy in measuring will lead to inaccuracies. Photocopies of drawings may not be to the scale of the original. This is because the drawing is only a representation and may not be exact. Measuring lines on a drawing to determine the measurement is not an accurate way to extract dimensions. To find the dimension you need, you may need to refer to other views or you may have to add or subtract other dimensions. If there are a number of parallel lengths, only one will have a measurement. Drawings normally only give each dimension once. Any measurements that you need should be somewhere on the drawings. The best way to get exact dimensions from drawings is to use the explicit dimensions (in millimeters or in feet and inches) written between the dimension lines.
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