How to give circle segments of diffenrent radiuses the same length?

[hendrik.schaeferX36WU]

Hello forum,

in Fusion 360 I am trying to give circle segments of diffent radiuses the same lenght and I do not find a propper way to do it. 

As this may sound difficult I will give you an example: There is a circle segment of 40° with a radius of 15 mm. I can read from the measurements window, that this circular segment is 10. 472 mm in lenght. 

Now I want to transfer this identical length to a circular segement with a radius of 20 mm - resulting in a different angle for the segment.

The = feature only seems to work for straigt lines in this purpose, as trying to apply it, leads to an error. 

Simply by testing the the above scenario, I figured out, that the result for the 20 mm segment is 30°. Is there a possibility, that Fusion 360 can calculate the angles (or diameters) to a given circular segment?

Thank you and best regards,

Hendrik

[TrippyLighting]

The arc length you measured with the measure tool cannot be used directly by Fusion 360 to dimension another arc.

You'll simply have to use a little math to do that.

1. Sketch an arc and dimension the radius and the Angle. 

Arc Length = θ × (π/180) × r, where θ is in degree, where,

• L = Length of an Arc
• θ = Central angle of Arc
• r = Radius of the circle

2. Sketch your second arc and dimension the radius. Solve the equation above for the Angle and plug that into the dimension field for the Angle. Done!

[HughesTooling]

If you convert the angle to radians in a parameter it quite easy to calculate. For the length from an angle and radius it's (Arc/rad) * radius. (the /rad converts the angle to radians) Then for the second arc it's the first arc's length divided by the second arc's radius * 1 radian will give the angle in an angle parameter.

Like this.

[TrippyLighting]

Thanks! It did not occur to me to convert that to RAD.

Calculating this in Degrees instead of RAD isn't all that complicated either until you try entering that formula into a user parameter and Fusion 360 refuses to accept it.