You measure the ratio of the angle on the frog... measure across the frog rails at some point distance from the "point" of the frog, and reduce the 2 numbers to 1:something.
One easy way is go along the frog until the rails are 1 inch apart, then measure from that place back to the point (or where the point should be if the point of frog has been blunted off)...
That number is the frog number. The higher the number, the less the angle...
By the way, I'm guessing you might have some confusion, there is an Aristo "wide radius" switch, which is not a #10, more like a #4... the "10" refers to the radius of the curved part.
I might suggest you read: http://www.elmassian.com/trains-mainmenu-27/track-mainmenu-93/turnouts-in-general
and http://www.elmassian.com/trains-mainmenu-27/track-mainmenu-93/lgb-track-a-switches
Hope this helps getting you started.
Greg
Visit my site: http://www.elmassian.com - lots of tips on locos, rolling stock and more.
Click here for Greg's web site
How can you determine the size of a switch? What is the difference between a #6 and a #10 (or wide) switch?
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