turnout number in relation to radius

[brubakes]

#4, #6, #8, ect.... What do those numbers mean in terms of the radius of the curve. Meaning does a #4 = 18", #6 - 20", ect....

 

[GWT&P]

Actually, turnout numbers don't necessarily have anything to do with radius. The turnout # has to do with the amount of divergence from the through track. A #8 diverges 1 unit for every eight units of through track, a #6 diverges 1 unit for every 6, and a #4 diverges 1 for every 4. As far as Atlas turnouts go (all I know about), the #4 is actually about 4.5.
With these measurements the Atlas #4 diverges 12.5 degrees from the main, a #6 - 9.5 degrees, and a #8 - 7.1 degrees.
Hope that helps.

 

[ken_23434]

The #'d turnouts are not the same as the "Atlas Snap Track Turnouts". Those will equal a section of an 18" curved section of track. They do this, so it is easy to stick the turnout into a layout done with sectional track. The turnout will just take the place of a normal 18" section of track and the rest of the alignment is taken care of. The diverging route is a "curved" route.

The #'ed turnouts have the diverging route as a straight line, just at a specified degree as mentioned above. Think of the #'ed turnouts as being the intersection of 2 straight tracks at a certain angle. The start of the diverging route will have a slight curve, but only minimal. So, you cannot use a #'ed turnout in the place of a segment of a circle.

http://www.handlaidtrack.com/document_general_info.php?products_id=2224

There is a link to a site that has free templates you can download for various turnouts. They are intended as a template for building your own, but they are handy for layout aids. If you download the template and look at it with a regular Atlas Snap Track turnout sitting on it, you can see the difference.

The #4 turnout is pretty close to the standard Atlas Snap Track turnout. If you build a section using the standard turnout, and then only swapped out the turnout with a #4 and left the rest of the tracks in place, you would see that the diverging route does not line up with the #4 turnout.