Drawing parallel curves?

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Having trouble figuring out how to draw parallel 13.5 radius curves. I have the outside curve drawn. I have my center lines spaced at 1.5". Can't get the inside curve drawn to match. What am I missing?

Thanks so much.
Last edited:


Well-Known Member
They can't be the same radius. If your outer curve is 13.5" radius and the track spacing is 1.5" then the inner curve needs to have a 12" radius.

If you want both curves to be 13.5" radius, then you need to move the center and the curves will not be concentric (parallel for curves.)

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