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Drill bit sizes are written as irreducible fractions. So, instead of 78/64 inch, or 1 14/64 inch, the size is noted as 1 7/32 inch. Below is a chart providing the decimal-fraction equivalents that are most relevant to fractional-inch drill bit sizes (that is, 0 to 1 by 64ths).
Example (inch, coarse): For size 7 ⁄ 16 (this is the diameter of the intended screw in fraction form)-14 (this is the number of threads per inch; 14 is considered coarse), 0.437 in × 0.85 = 0.371 in. Therefore, a size 7 ⁄ 16 screw (7 ⁄ 16 ≈ 0.437) with 14 threads per inch (coarse) needs a tap drill with a diameter of about 0.371 inches.
A fixed-point representation of a fractional number is essentially an integer that is to be implicitly multiplied by a fixed scaling factor. For example, the value 1.23 can be stored in a variable as the integer value 1230 with implicit scaling factor of 1/1000 (meaning that the last 3 decimal digits are implicitly assumed to be a decimal fraction), and the value 1 230 000 can be represented ...
Exmples (approximate dimensions, for masonry drills: 6 - about 4mm, No. 8 about 3/16 inch or 4.5mm, No.9 about 5mm, No.10 about 5.5mm etc. I cannot find any discussion of this scheme for giving the sizes of drills but it should at least be mentioned as a historical system, in use at least until the 1990s. Thank you.
The correct tool to start a traditionally drilled hole (a hole drilled by a high-speed steel (HSS) twist drill bit) is a spotting drill bit (or a spot drill bit, as they are referenced in the U.S.). The included angle of the spotting drill bit should be the same as, or greater than, the conventional drill bit so that the drill bit will then ...
[14] [15] It is said to be an improper fraction, or sometimes top-heavy fraction, [16] if the absolute value of the fraction is greater than or equal to 1. Examples of proper fractions are 2/3, −3/4, and 4/9, whereas examples of improper fractions are 9/4, −4/3, and 3/3.
The standard designation for a UTS thread is a number indicating the nominal (major) diameter of the thread, followed by the pitch measured in threads per inch.For diameters smaller than 1 / 4 inch, the diameter is indicated by an integer number defined in the standard; for all other diameters, the inch figure is given.
For example, the freezing point of water is 0 °C and 32 °F, and a 5 °C change is the same as a 9 °F change. Thus, to convert from units of Fahrenheit to units of Celsius, one subtracts 32 °F (the offset from the point of reference), divides by 9 °F and multiplies by 5 °C (scales by the ratio of units), and adds 0 °C (the offset from the ...