Turnouts

[Edavillenut]

what is the difference between #4, #6, and snap-switches.
i only use atlas track and i think i made the mistake by buying snap-switches. well this is my first layout so does that make a difference

 

[TinGoat]

Turnouts are measured from the point of the frog to where the mainline and the siding have seperated by one increment (Prototype foot). If it is four feet from the frog point to where the rails are one foot apart, then it is a #4 turnout.

I think that Atlas snapswitches are about a #5.

The higher the #, the gentler (more prototypical) the curve.

 

[rockislandmike]

I inherited a bunch of Atlas snap-switches from my brother, so I started using them as well. They're "okay", but I use Peco insulfrogs exclusively now. A few more bucks, but they look and work significantly better IMHO.

The exit-curve is also much more gentle than the Atlas snap-switches. If I remember correctly, the exit curve on the snaps matches up with an 18" curve, while the Peco minimum (small-radius turnout) is a 24" radius (medium = 36; large = 60). Interestingly, it looks like they're considered a #4.5 frog.

I wanna switch to a smaller rail for my diorama, as it's supposed to be a shortline, but I have yet to do the research to see if Atlas and Peco match on another code (I use Atlas flex track and some sectional track with the Peco turnouts on the current layout, all code 100).

 

[Edavillenut]

atlas makes code 83 in ho and code 55 in n scale i think

 

[60103]

Some people claim that the snap switches don't have a number because they're curved right through. The rail through the frog should be straight. (Unless you model streetcars) Numbered switches have two radii associated with them -- the minimum radius of the curved bits, which determines what rolling stock will go through them, and the replacement radius which is the curve that the switch will fit into. The replacement raius is always a lot larger that the minimum radius since there are lots of straight bits at the end of the switch.
Even snap switches have 1.5" of straight before the points.