coil calculator questions finding the inner radius

[calebsone]

I am only asking to make sure I am right on the way to use it. if I had a circle of 241mm I would measure from the exact center to the inner edge of the circle that is the first layer of the wire. ok now that's out of the way here is the hard one for a dd coil that is say 292mmX157mm I add the two then divide that by 4 or do I take the inner radius of the 292 full circle and the 157 add and divide that by 4.

[Qiaozhi]

I am only asking to make sure I am right on the way to use it. if I had a circle of 241mm I would measure from the exact center to the inner edge of the circle that is the first layer of the wire. ok now that's out of the way here is the hard one for a dd coil that is say 292mmX157mm I add the two then divide that by 4 or do I take the inner radius of the 292 full circle and the 157 add and divide that by 4.

You can take the two inner diameters (292mm and 157mm), add these together and divide by 4. (Answer = 112.25mm)
OR
Take the two inner radii (146mm and 78.5mm), add these together and divide by 2. (Answer = 112.25mm)

What you're basically trying to get is the average value of the two inner radii.

[calebsone]

ok good that's the answer I got 112.25 I just used the first way but I see you can do it both ways thank you for your help.