Track Radius, Inside Rail, Center, Outside Rail

[trammayo]

Dave - I've just measured the outside radius (of the ties) and get a nominal 25". That, of course, gives a an external diameter of 50" or 4ft 2ins. I used LGB track and have mixed with Aristo track for switches and other curves (all are R1's - switches or curves + straights of course. I have it all set up in a trailer!

 

[Greg Elmassian]

I have two 2-rail track benders, I have no problems with track fitting

 

[justme igor]

definitely the center line is the standard. You can easily calculate the radius of the outer rail, just add 1/2 of 45 mm and then 1/2 of the thickness of the rail itself. that is the outer rail... for the inner rail radius, subtract these two items.

Yes, the centre line is always correct.
Also your calculations method is correct

For other measurements take a pencil and a string of rope on your desired diameter divided by 2, draw the curve you want and you will have your centre line.
There are a lot of ways to calculate your curve with a piece of strait metal( 1 foot 33 cm or 3.3? foor 1 meter) and measure that gap.

Or my favourite now these days:
Download templot, change into your scale, change into a curviform(istead of your turnout startup), change to the desired radii and print it, make a mold from that print or use it as it is.
one meter or 3.3 foot in length would be desirable.
You will get it true to your wish, including the "next outer or inner lane" at precise measurements of your wish.

With best regards Igor