- #1

SevenToFive

- 56

- 3

Any help is greatly appreciated.

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- Thread starter SevenToFive
- Start date

- #1

SevenToFive

- 56

- 3

Any help is greatly appreciated.

- #2

russ_watters

Mentor

- 22,133

- 9,280

1/8" is a fraction of the circumference and arc min is the associated angle.

Any help is greatly appreciated.

- #3

Let'sthink

- 350

- 81

18" is radius and the angle is [1/(8*18)] rad = [{(180*60)/(8*18)}/π] arc min = 75/π = 23.87 arc min

Last edited:

- #4

Tom.G

Science Advisor

Gold Member

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D =36"

Allowed Move = 1/8" = 0.125"

Circumference = π⋅D = 113.1"

Circum/Allowed Move = 113.1/0.125 = 904.8 (the fraction of a revolution req'd to move 1/8")

Allowed Rotation = 360°/904.8 = 0.3979° = 23.87 arc min

- #5

Let'sthink

- 350

- 81

I am sorry I had committed a calculation mistake,now I also get the same answer.

D =36"

Allowed Move = 1/8" = 0.125"

Circumference = π⋅D = 113.1"

Circum/Allowed Move = 113.1/0.125 = 904.8 (the fraction of a revolution req'd to move 1/8")

Allowed Rotation = 360°/904.8 = 0.3979° = 23.87 arc min

- #6

Baluncore

Science Advisor

- 12,351

- 6,424

So 1/8” on a radius of 18” = 1 in ( 18 * 8 ) = 1 in 144.

Apply the 1 in 60 rule, then multiply degrees by 60, to get ( 60 * 60 / 144 ) = 25 arc min.

The 1 in 60 navigation rule comes from 1 radian ≈ 57.29578 degrees.

Mathematically we have ( 60' * 57.29578° / 144 ) = 23.8732 arc min.

- #7

SevenToFive

- 56

- 3

Thanks everyone for the replies. Greatly appreciated.

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