More Help For The N Scale n00b, Please

Discussion in 'N / Z Scale Model Trains' started by Cannonball, Apr 13, 2007.

  1. Cannonball

    Cannonball More Trains Than Brains

    How do you guys know which switches to use?

    In O gauge, it's easy.
    If you're using O72 curves, you use an O72 switch.
    O31 curves use an O31 switch.
    O27 curves use an O27 switch.

    With N scale, the switches are all numbered #5 switch, #7 switch, #3 switch...... etc.
    How do you know which is which??

  2. baldwinjl

    baldwinjl Member

  3. Cannonball

    Cannonball More Trains Than Brains

    Ok..... I just looked at those and I'm more confused than before.

    What the heck is RP-11 and RP-12?
    How can each switch size have 2 or 3 different minimum curves?
    That stuff is like reading physics or something.
  4. pgandw

    pgandw Active Member

    It's not quite that bad. Prototype switches (usually called turnouts in scale circles) have straight frogs (the frog is where the rails cross each other). This means the turnout has bits and pieces of curves separated by straight sections. Scale model turnouts are laid out in much the same way. This means you cannot simply substitute a turnout for a piece of curved track like you can in 3 rail. Some N track manufacturers do make turnouts with curved frogs and a single radius throughout the curved leg of the turnout. Atlas Snap Switches, and some Bachmann, Lifelike, and Kato turnouts fall into this category.

    The frog angle on a straight frog is measured by the number of units (inches) one must go on the diverging side of the frog point to get one unit (inch) of separation between the 2 rails. On a #5 turnout, you will achieve 1 inch of separation between the 2 frog rails 5 inches from the frog point. The smaller the frog number, the sharper the curves in the turnout, and the shorter the turnout is.

    The sharpest curved section of a scale turnout is in the closure rail section (dimension 11 on the NMRA RP12 diagrams and tables). You want the radius of this section to be as big as or bigger than your minimum radius for that area of track.

    The RP numbers are just a scheme used by the NMRA to catalog their standards and recommended practices. A standard starts with S and means required for NMRA conformance; RP means recommended practice but is not a requirement. RP11 gives good, conservative guidance for turnout #s and minimum radius curves for various types of rolling stock.

    FWIW, Atlas and GarGraves and others do make straight frog turnouts in 3 rail O, as well as the designated radius curved frog ones (O36, etc).

    Hope this helps
  5. Cannonball

    Cannonball More Trains Than Brains

    So does curve raduis matter then?
    It sounds to me like the way the switches are designed make them more dependant on the distance between each other rather than the curve radius of your track.

    Like I could put 9" curved track between two #7 turnouts as long as they were close enough to complete the curve? Or I could put #3 turnouts on an 12" curve?

    Am I getting anywhere close???
    *starts thinking Atals track packs are not such a bad idea*
  6. baldwinjl

    baldwinjl Member

    I think you are catching on at bit. You have hit on the critical point. A numbered turnout is not a straight track with a curve superimposed on it. It is one of the things that can make sctional track a bit of a pain, and also why there are some oddball pieces available to make things work out. If you start with a plan that was made for it, sectional track works fine. Flextrack gives you more, dare I say it, flexibility.

  7. Cannonball

    Cannonball More Trains Than Brains

    I'm heavily leaning towards flextrack anyway. Fewer rail joints to deal with.
    Do they have some sort of guage to go by so the curves aren't too sharp?
    My curves don't have to be perfectly round with flex track, do they?
    I just don't want to kink the stuff or make a corner my trains couldn't navigate.
  8. baldwinjl

    baldwinjl Member

    Kinks are bad. That's where care patience come in. If you get too slpdash you can make a kink in a straight joint.

  9. pgandw

    pgandw Active Member


    I recommend you take a look at some of the Atlas N layouts on this page:

    Under the layouts tab is a listing of their N layouts books. I recommend either one that strikes your fancy. Although strictly oriented around Atlas track and other products, most everything applies to other N track lines as well. Also, the RTS 7.0 software download (free) gives you a fairly easy way to do some track planning with numbered turnouts (Atlas only) and flex track.

    As you have learned, straight-frog turnouts cannot be dropped into an existing fixed radius curve without having to redo/replan the entire curve. You want to set a minimum curve radius that is suitable for your equipment and space. That's what the NMRA RP11 reference was all about. If you are thinking of running full length passenger cars, big diesels, or long freight cars like auto racks and double stacks, you will want a minimum radius up around 15". If 4 axle diesels, and 40ft freight cars are your preference (and you will never buy the bigger stuff), you can get away with a 9" minimum radius.

    When you lay flex track, you normally draw the curve out on the table (use a yardstick) and then lay the roadbed and track to the lines.

    A word of warning: N scale is very unforgiving of trackwork problems compared to O27. Any kinks or vertical irregularities will cause derailments.

    my thoughts, your choices
  10. Cannonball

    Cannonball More Trains Than Brains

    Thanks Fred.
    I'm looking at the layouts (and YIKES they are pricey!)
    I'll look into the books and see what info I can gather from them.
    I've got the RTS program downloaded already and have been messing with it a bit this morning. Gonna have to wait to play some more until I get home from work tonight now.

    15" for passenger cars, huh?
    hhhmmmm....... I was hoping I could get away with smaller but I've already got the Santa Fe passneger set coming.

    Thanks to everyone else for your input as well.
    Hopefully I'll eventually get this figured out.
  11. Denyons

    Denyons Member

    Attached Files:

  12. MasonJar

    MasonJar It's not rocket surgery


    Not to confuse things further, but aren't Peco turnouts described as "large". "medium", nad "small"? And they do actually have a curved diverging route? (At least, they do in HO scale).

  13. pgandw

    pgandw Active Member

    The Atlas track typically sells at substantial discounts at mail order and online stores.

    It's likely your passenger set will do less; obviously whatever radius track comes with the set will work, and is likely to be the practical minimum. 15" is a rather arbitrary suggested radius for reasonable appearance and overhang, as well as a lot less propensity to string-line. Some makes of passenger cars will do smaller radii than others by removing under-body details and allowing greater coupler swing. Mounting couplers on the trucks instead of the body permits quite a bit tighter radius.

    Part of the joy (IMHO) of modeling in N scale is the ability to use relatively larger curve radius with the improved appearance, reduced overhang, and longer trains in a reasonable space.

    Enjoy your new set regardless.
  14. Denyons

    Denyons Member

    You are correct Andrew.
    If I remember rightly, Peco always used the numbers 4 / 6 / and 8 for their Small Medium and Large turnouts.
  15. jesso

    jesso Member

    Cannonball, a lot of the time, minimum radius is for looks. There are sometimes requirements, but a lot of the time those requirements are 9 3/4 or up. My LONG Kato SD70MAC, even on the Kato sheet, says it will run on 9 3/4 (and it does) , they don't recommend their 8 inch track. My AutoMax's have a place to change the screw connectors to to do less the 9 3/4 track, and those cars are HUGE! However, going around the curves you can see the "wierd" movement and you will see the track in the middle of the car as they go around the curves. However, as you were running 027 curves, these won't be as noticeable as they were running around the curves on that track.

    Our club layout has 14 1/2 minimum radius, although I am sure some points are a little tighter than that. All the Peco switches on it are the mediums, and everything that has ever been put on it runs fine, from the 0-6-0 Thomas that I own to the 4-6-6-4 Challenger that one of the club members just got. I have also run my long engines and passenger cars and automax's on a 9 3/4 layout, and they all run well, they just "look" a little weird as the track will show. Again, it is what matters to you.

    Although again, experiment to your tastes, and to you equipment. See what track comes with your set and go from there.
  16. Cannonball

    Cannonball More Trains Than Brains

    So wich ones do you have on your layout?

    And that is an incredible looking layout by the way. :eek:
  17. Cannonball

    Cannonball More Trains Than Brains

    I think this will be the most logical solution.
    I'm pretty sure the set comes with Model Power's equivilant of EZ track.
    I doubt I stick with that but it will give me an idea of what switches I'm looking for.
  18. Jim Krause

    Jim Krause Active Member

    Cannonball: May I suggest that you buy one piece of flex track of your choice and experiment with it to see just what can be done in the way of curves. It takes some real effort to actually kink it. The biggest problem will be getting the rail joints aligned on curves. The less joints on a curve, the better.
  19. Cannonball

    Cannonball More Trains Than Brains

    Yeah, I think I can see where a joint on a curve could be trouble.
    I will definately have to do some playing around before I get serious anyway.
  20. Denyons

    Denyons Member

    The majority of my Peco turnouts are #6 or Medium length but you will notice on the photo of the yard entrance (Half cork) that I have a Shinohara 3 way Wye followed by a Peco 2 way Wye.
    All my track work is done with Atlas Code 80 Flex Track.
    I did use one more Shinohara turnout and it is a Sissors Xover.
    I installed 2 Tortoise machines and made bell cranks so one tortoise will operate 2 of the turnouts and the other operates the opposing turnouts.


    Attached Files:

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