You have a wonderful day. Best wishes. Deas Plant.
If you get to the store and forgot to consult the chart, here is a easy way to figure the tap drill size for 75% thread on 60 degree V threads:
1) for inch sizes, divide 1 by the pitch and subtract from the major dia. Example, for 1/4-20 divide 1 by 20 = .050", substract from .250 = .200 and the tap drill size is a #7 drill bit at .201"
2) for metric subtract the pitch from the major diameter. Example for M6 x 1.0 subtract 1.0 from 6mm = 5mm if you do not have metric drills use the nearest size from the letter, number, or fractional drill bits.
It always works & tap drill charts are figured for 75% thread anyway.
If you get to the store and forgot to consult the chart, here is a easy way to figure the tap drill size for 75% thread on 60 degree V threads:
1) for inch sizes, divide 1 by the pitch and subtract from the major dia. Example, for 1/4-20 divide 1 by 20 = .050", substract from .250 = .200 and the tap drill size is a #7 drill bit at .201"
2) for metric subtract the pitch from the major diameter. Example for M6 x 1.0 subtract 1.0 from 6mm = 5mm if you do not have metric drills use the nearest size from the letter, number, or fractional drill bits.
It always works & tap drill charts are figured for 75% thread anyway.
Thank you too Deas Plant! It's so convenient to have such a wealth of info available to us...sometimes I take it for granted.
Much appreciated
If you get to the store and forgot to consult the chart, here is a easy way to figure the tap drill size for 75% thread on 60 degree V threads:
1) for inch sizes, divide 1 by the pitch and subtract from the major dia. Example, for 1/4-20 divide 1 by 20 = .050", substract from .250 = .200 and the tap drill size is a #7 drill bit at .201"
2) for metric subtract the pitch from the major diameter. Example for M6 x 1.0 subtract 1.0 from 6mm = 5mm if you do not have metric drills use the nearest size from the letter, number, or fractional drill bits.
It always works & tap drill charts are figured for 75% thread anyway.
Our channel highlights machines from the earliest Holt and Best track-type tractors, equipment from the start of Caterpillar in 1925, up to units built in the mid-1960s.
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