Can't do the math!

omrc7771 · May 2, 2014

I am going to machine a base for mounting a scope on a rifle. The base will be 6" long and I need to machine a taper on it that is 20 MOA (minutes of angle) what will be the difference in height of each end be? Hope I explained it right. Thanks.

Davis In SC · May 2, 2014

Just off the top of my head, about .035 ?

Silent_Man · May 2, 2014

Close Davis, but the right answer is .03491

Those gun guys know 9 tenths of a tenth makes all the difference.

Also, that number is radial. Double it to find the difference if youre measuring diameters.
(Eta: dont know why I thought you were turning this...)

Showing my work:
Sin (alpha)=h/L
h=L *sin (alpha)
h=6*sin (20/60)
h=.03491

tjb1 · May 2, 2014

20' = .333333

sin(.333333) * 6" = .0349063532"

omrc7771 · May 2, 2014

Thank you, I was just drawing a blank.

easymike299 · May 2, 2014

tjb1 said:
20' = .333333

sin(.333333) * 6" = .0349063532"

That should be Tan, not Sine

Gene

dsergison · May 2, 2014

there is no real difference in the adjacent vs the hypotenuse at that angle are we supposed to argue whether the scope rings are 6" apart on the scope, or 6" apart on the scope base now?

tjb1 · May 2, 2014

easymike299 said:
That should be Tan, not Sine

Gene

My bad

20' = .333333

tan(.333333) * 6" = .034906944"

I just did it like a sine bar calculation the first time.

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