Atlas 3 rail #5 turnout to parallel main help needed.

I guess I don't understand your question.  Are you wanting to know what to use to get a parallel track off of a #5 switch?  The answer would be an Atlas O-72 half curve.  If you use it right on the switch, then you get a center to center track spacing of about 2.94 inches.  If you want to have a more uniform Atlas center to center spacing of 4.5 inches, you'd need a straight piece of about 8.11 inches between the switch and the O72 half curve.  As that's a custom cut size, you can either get closer spacing (Which would be like 4.49 inches.) with 8 inches of straight between the switch and O72 half curve (Using either the combination of 1.75+1.75+4.5 or 1.25+1.25+5.5 track lengths.) or farther spacing (Close to 4.6 inches.) using 8.25 straight (Made with 1.75+1.75+1.75+1.75+1.25.).

I'd personally use the 1.75+1.75+4.5 combination to get me the close 4.5 inch spacing.

For a #5 you will need an 11.25 degree curve to return to parallel.  The #5 turnout "curvature" is roughly equivalent to an O81 curve.  Since there are 16 curve pieces in a large diameter circle each is 22.5 degrees so you need a 1/2 curve.  Atlas makes a 1/2 O72.  You will need to put a section(s) of straight track to get the spacing between the parallel runs you desire,

A 10" straight and 1/2 O72 curve will get you 5" spacing.

A 4.5" and two 1.75" straights and 1/2 O72 curve will get you 4.5" spacing.

If you cut a larger diameter curve to get the 1/2 curve you will need to adjust the length of the straight section.  Use RRTrack or SCARM to work out the length you need.  For what it's worth you get 0.2 inch of separation for every inch of straight you use.

Jan

Thank you gentlemen..very helpful.

sinclair posted:

I guess I don't understand your question.  Are you wanting to know what to use to get a parallel track off of a #5 switch?  The answer would be an Atlas O-72 half curve.  If you use it right on the switch, then you get a center to center track spacing of about 2.94 inches.  If you want to have a more uniform Atlas center to center spacing of 4.5 inches, you'd need a straight piece of about 8.11 inches between the switch and the O72 half curve.  As that's a custom cut size, you can either get closer spacing (Which would be like 4.49 inches.) with 8 inches of straight between the switch and O72 half curve (Using either the combination of 1.75+1.75+4.5 or 1.25+1.25+5.5 track lengths.) or farther spacing (Close to 4.6 inches.) using 8.25 straight (Made with 1.75+1.75+1.75+1.75+1.25.).

I'd personally use the 1.75+1.75+4.5 combination to get me the close 4.5 inch spacing.

My "2 mains" spacing center to center rail is 3.25 inches on the rest of my layout. Looks like a short straight section and an Atlas O-72 half curve will get it close.

Two 1.25 straights and the 1/2 O72 curve will get you 3.5" spacing.

Jan