V bit depth of cut

Specifically, you know two values:

  • diameter to which you wish to cut
  • V angle

I always look this sort of thing up at:

so assume the V endmill is on its side, and half its angle equals angle alpha and the dimension a == half the width which we wish to cut to, so we are trying to determine length b — given for an example:

  • 60 degree V endmill
  • cutting to a width of 0.75"

We need to enter the values:

  • alpha == 30 degrees
  • a == 0.375"

and

b == 3/8" / tan(30 degrees)

tan of 30 degrees == 0.577350269

so we EDIT: correction divide (not multiply):

3/8" / 0.577350269

to get:

0.649519053

for the depth which we need to cut to.

For an example of drawing things up in profile and just setting the depth thus see

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