Milling math

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• 06-12-2019, 01:06 PM
Video Man
ANNND- it works a treat, thank you, Marv Klotz! As to a cad program, they have their uses, but I punch up calculations on my workshop computer rather than booting a cad program and wading through that. And it's been a little hobby for many years to write these BASIC programs, mostly for my own entertainment. Thanks to all who replied!
• 06-12-2019, 01:24 PM
lynnl
Quote:

Originally Posted by rjs44032
Using my formula:

360 degrees * pi/180 = radians
360 * 0.17453293 = 6.283185307 (in radians)

Best Regards,
Bob

Hmm, maybe we're speaking a different math language. Maybe my math skills have atrophied even more than I thought.

But to me if that line 360 degrees * pi/180 = radians is to be treated as a formula, then there is an implied coefficient of 1 in front of radians. Then multiplying both sides by 180 and dividing both sides by pi it becomes 360 degrees = 180/pi radians, ... which gives us: 360 degrees = 57.29 radians (????)

I think that's too many doggone radians.
• 06-12-2019, 02:18 PM
RB211
Quote:

Originally Posted by mklotz
And you would have learned exactly no math that would be useful in other applications.

Plus, had you learned some math, you could solve this problem in your head in two seconds...

The distance from the center of a flat to the opposing vertex (dfv) is clearly the sum of the distance from the center to the vertex, the radius (r) of the circumscribed circle, plus the apothem distance to the flat which is r times the cosine of the polygon half angle [360/(2N)].

Thus...

dfv = r * (1 + cos[360/(2N)])

or

r = dfv / (1 + cos[360/(2N)])

and the diameter is twice that.

Did you teach math in the Redding school district in CT? Because you sound just like my math teachers

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• 06-12-2019, 05:04 PM
rjs44032
Quote:

Originally Posted by lynnl
Hmm, maybe we're speaking a different math language. Maybe my math skills have atrophied even more than I thought.

But to me if that line 360 degrees * pi/180 = radians is to be treated as a formula, then there is an implied coefficient of 1 in front of radians. Then multiplying both sides by 180 and dividing both sides by pi it becomes 360 degrees = 180/pi radians, ... which gives us: 360 degrees = 57.29 radians (????)

I think that's too many doggone radians.

Ok. Perhaps this is better:

Let rVal = value in radians
Let dVal = value decimal degrees

Then use the following equations for conversion:

rVal = dVal(pi/180)
dVal = rVal(180/pi)

if dVal = 360 then rVal = 360(pi/180) = 360(0.017453293) = 6.283185307
if rVal = 6.283185307 then dVal = 6.283185307(180/pi) = 6.283185307(57.29577951) = 360

Hope this helps clarify. Sorry for the confusion. There was a typo in my previous response. 0.17453293 should have been 0.017453293.

I always think in logical terms and sometimes the point gets lost in the translation. That's why I am not a Math Professor. :)

Best Regards,
Bob
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