Calculating the lead of a twist drill
November 20th 2008 12:48 pm By Web Development in India
I see a lot of people use trig to calculate a drill tip or to calculate how much deeper to go with the countersink. A quicker way to calculate a 118 degree drill tip is to multiply the dia. by 0.3 i.e.: 0.250 X .3=0.075 The .3 is a standard established by the fact that your answer would be .3 if it were trig’d out for a 1″ dia. Try it! You can do the same for different countersinks, too. Use the value 0..575 (instead of 0.3) for an 82 degree countersink.