How to draw an Atlas N #4 turnout

Discussion in 'FAQs' started by Biased turkey, May 3, 2007.

  1. Biased turkey

    Biased turkey Active Member

    I want to draw the centerline for the straight and diverging part of an Atlas code 80 N scale turnout using basic drafting tools, such as a ruler, a protractor , a homemade compass that allows me to draw "standard" Atlas N scale curves: 9 3/4", 11" and 19" radius.
    I have Xtrkcad, how could I extract all those dimensions from the turnouts library ?

    Tia for any info
  2. doctorwayne

    doctorwayne Active Member

    Why don't you simply buy one turnout, doesn't really matter if it's left or right, unless your planned layout will only use rights or lefts. ;-) Then, trace its shape on a piece of paper and label it (if it's a "left" and you cut it out, then the opposite side becomes a "right" - I did this with an Atlas code 83 #6 when planning my layout, although I used I piece of boxboard for durability.) Using a scale ruler and a compass, you should be able to figure out whatever you need to know.

  3. baldwinjl

    baldwinjl Member

    Or, lay down a turnout in XTrkCad, print out full size, and measure it.
    Or, you could look at that parameter file and try to figue out what is what. I took a quick look and decided that wasn't a good idea.

  4. Biased turkey

    Biased turkey Active Member

    Thanks to both of you for the suggestions.
    I found what I was looking for in the Kalmbach book " Track Planning For Realistic Operation ".
    The book lists all the turnout dimensions for all the turnouts # in all the scales.
    For example, the Atlas N scale #4 has a radius for the curved leg equal to 19" and Trix has a 13" radius.
    The reasom I asked the question is to allow me to make cardboard templates of the switch centerline in order to locate the cork roadbed centerline with a good accuracy.
  5. pgandw

    pgandw Active Member

    Numbered frog turnouts (#4, #5, #6, etc) do NOT have a constant radius through the curved section. They have a straight section through and beyond the frog. The curve is mostly in the closure rail, and the closure rail radius is actually the controlling radius of the turnout.

    Atlas Snap Switches, most Peco turnouts, and most train set turnouts DO have a constant radius curved leg.

    The radius listed for #4 turnouts in Track Planning for Realistic Operation is probably the "substitution radius". If you drew a continuous curve of the substitution radius the curved leg of the turnout would likely fit without modifying the curve, even though portions of the turnout will be considerably sharper than the substitution radius. The subsitution radius is acceptable for preliminary track planning, but will not give you the information to lay cork roadbed centerlines accurately.

    But I have to ask myself - why would you want to lay out your cork roadbed without at least one turnout already in hand? After you have designed your track plan, the best way to get the cork centerlines is to actually lay the real track out on the plywood or foam surface, and mark the centerlines. Take up the track, lay the roadbed, then reinstall the track. Very few of us lay track exactly as the computer program specifies.

    just my thoughts
  6. doctorwayne

    doctorwayne Active Member

    This is a very good point: no matter how much planning you do, sooner or later you're going to have to lay some track. (Well, you don't really have to, but in that case, you should really go out and buy a nice comfy chair):wink:
    I had a trackplan drawn for my layout, but threw it away when I lost almost half of my layout room to other family uses. Actually, it wasn't even much of a trackplan: a dimensioned sketch of the room, with some track lines sketched in, plus a few notes on industries or features. For the current, oddly-shaped room, I built open-grid benchwork in 8' or 10' sections, the widths dictated by the aisle width that I felt necessary. Then I made a dimensioned drawing of what I had, sketched in some new track lines, and went out and bought an Atlas Code 83 #6 switch and a case of track. Next, I cut up a sheet or two of 3/4" plywood into various radius curves, starting at 30", 32", and so on. Using the curves and pieces of 1"x2", 1"x3", and 1"x4", I laid out various configurations until various sections began to look like what I had in my head (ewwww!!):eek: I made some cardstock copies of the turnout, dropping them in to see if they'd fit, then re-arranging the curves and lumber until I liked it and everything fit. You can see the reason for choosing flex track, I'm sure, and you might want to keep that in mind, no matter how small or simple a layout you might have in mind.
    From there, I simply fastened the roadbed in place, adding risers where I thought they were needed, and so on. The only area that was later changed was to remove a crossover between the two mainlines on the curve between Lowbanks and Port Maitland, pictured below. It was behind the overhead crane, just ahead of where that loco is heading into the curve.

    Now, lest this sound all too haphazard, I did have a very clear picture in my mind of what I wanted, and for the most part, I got it. I just couldn't see any point to wasting time putting my thoughts down on paper. I did the same thing when I built my house. I had to have blueprints for the town building department, in order to get a building permit, but almost the only time that I referred to them was to make sure that I placed most stuff where I had told them I was going to place it. It wouldn't do to have the inspector get lost on the site! :oops: :lol:
    If you enjoy the technical aspects of trackplanning, by all means indulge yourself. I enjoyed sketching trackplans, too, but not with the details of curve radii and turnout dimensions crowding out the imaginative side of the task. Sooner or later, ya just gotta lay some track!!:grin: :grin:

  7. Squidbait

    Squidbait Recovering ALCO-holic


    IIRC, you're building a very small layout. 2'x4'? If you've done your track plan in XTrkCad, why not just print out the plan 1:1, paste it to your layout benchwork, and use a pounce-wheel or even a sharp pencil (or just glue the paper down) to give you a precise, pre-printed centreline?
  8. Biased turkey

    Biased turkey Active Member

    First, thanks again to all the nice members who took some of their precious time to post some detailed and interesting ( as always ) replies.

    To pgandw: My original idea was to get 1 piece of cardbord, lay an Atlas N #4 frog turnout and mark a dot ,every 3 or 4 ties , at the centerline of the branch curve. Then join those dots with a French curve.
    But John Armstrong mentions in the book that "Most sharp and conventional-curve N gauge prefabricated turnouts are of curved design ( E.G. Trix 13" radius , Atlas "Standard 19" radius). These can best be laid out by using a circular arc tangent with the straight-leg centerline and the actual dimensions C and P"
    C = Overall length ( measured parallel to the straight-leg centerline ) of curved length of turnout.
    P = Minimum straight section ahead of switchpoints.

    So like it or not I had to do some measurements on a real Atlas N scale #4 turnout in order to make a cardboard template.

    To DoctorWayne: I wanted a very accurate plan of my layout so the Preiser track inspector doesn't get lost :)

    To Squidbait: You are right, I'm building a 25" x 36" micro-layout and I used XtTrkCad to design it ( That's an obvious case of overkill ) . But that small layout gave me a reason to learn that software . For sure my 2nd and bigger layout will use the 1:1 scale printout to mark the centerlines.

    And as DoctorWayne mentions, I enjoy the technical aspects of trackplanning, but sooner or later I'm going to have to lay some track.

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