Drawing parallel curves?

[PittBull]

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.

 

[twforeman]

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.)

 

[montanan]

Try using a compass.