engraving a fixture.

Hello, I am new to the forums here.
Today a was asked to engrave some curves in a model. 3mm wide
what they want me to do is use a ball nose cutter, and cut on the line.
no problem
the problem is I dont have a 3mm ball nose endmill. I have a .250in ball.
what would the formula be to set the depth to get a .118in wide cut.?
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snipped-for-privacy@gmail.com wrote:

Courtesy of the Machinery's Handbook, 24th Edition, page 58.
h = r - 1/2 times the square root of (4r squared - c squared)
h is the depth you seek
r is, of course, the radius of the cutter
c is the chord length, .118 in your case.
Later,
Charlie
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On 5 May 2006 10:28:59 -0700, snipped-for-privacy@gmail.com wrote:

Without putting too fine a point on the obvious, just buy one.
your depth of cut is going to be much shallower than it should be. .058 vs .0148
Or how about a smaller ball and move it over. Take a center cut and then move half of the diameter difference to each side. It's really difficult to tell it's a bullnose instead of a half round
Will
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the cut is just meant to be a visual check, go/no-go on the model, 3mm trim tolerance. depth is unimportant.
thanks to all for the help, jobs done now, and looks great.
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Rob wrote:

So.... post a picture somewhere.
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