I have been comparing track and have become very confused about turnouts. I was comparing Atlas Customline turnouts to the new Peco code 83 turnouts and noticed that Peco has a #5 but not a #4. Atlas has a #4 but not a #5. What is the difference? I understand that the # designates frog angle but for the non-engineers that doesn’t mean alot. I also understand that the radius is diffrerent for the inside and outside rail. The lower the number, the lower the radius (I think). But what exactly is the radius for a #4, #5, #6, etc? And what is with those Shinohara turnouts with all kinds of crazy numbers? Is the frog angle a NMRA standard? Help!
Frog numbers measure how many inches (or any other measure of length) it takes from the frog to get a spread of one inch (or other unit). A #6 takes six inches to achieve a spread of 1 inch. Frogs with numbers are straight at the frog.
The measure of the curve before the frog is called the closure radius. Although this is sharper than most people realize - see NMRA data sheets for actual figures - the curve at the closure rails is quite short, usually less than the distance between the 2 sets of trucks on a diesel of car. Where the closure radius does impact is long wheel bases - 6 wheel diesel trucks, longer wheel base steam engines, passenger trucks - if these have trouble with 18 inch radius curves, they will struggle with #4 turnouts.
The Atlas #4 is really a #4.5 with a closure radius of about 22 inches.
Many Peco turnouts have the diverging track curve after the frog, which confuses things. The diverging curve has a radius, and the frog has a number.
Curved turnouts can use frog numbers or radius, depending on whether the the track through the frog is curved or straight. In curved turnouts, it is normally the substitution radius that is quoted. The 2 substitution radii of a curved turnout are generally more important for track planning than the frog number. Be careful of curved turnouts that have straight frogs - the radius quoted will be slightly higher than actual to make room for the straight frog.
A wye turnout (where both legs diverge equally) has a frog number half that of a conventional turnout with the same closure radius.
For your track plan, I would use nothing smaller than an Atlas #4, or #5 in other brands.
Hope this makes sense.
Fred W
Fred, thanx. It helps a bit. I did not know the # referred to length to a spread of an inch. From what you are telling me, I could use a Peco #5 turnout in place of an Atlas #4 which is key. I was considering changing my track to Peco 83 from Atlas 83 because I like the protypical look of the Peco 83. I would love to use Walthers but the delays I am hearing about are a nightmare and I simply do not want to mix different kinds of track.
I still find it unneccesarily confusing. Particularly when track planning with software. Curves and turnouts never seem to meet correctly. Some brands of turnouts have cut-off curves (like Atlas) and others don’t. Do you really have to be a Draftsman or Architect to figure a good track plan? How do some people come up with huge layouts on paper? Must take forever. I will plod on in my quest…
For any but the simplest layouts, meeting curves to turnouts means that flex track is required. Trying to use sectional track and have the turnout radii correspond to sectional radii means using Atlas “Snap” turnouts which have an even tighter radius (18") than Fred was mentioning for an Atlas #4… they can be problematic. Good software (I use Xtrkcad) can make it all a breeze.
When planning your layout, it is best to find a website or a reference such as Walther’s Catalogue that will give the actual dimensions of a particular brand of turnout. This is because the frog number gives only an APPROXIMATION of the distance you have to go before the the track diverges one inch from the straight. Consequently, a #4 frog may , in fact be a 4.5, a #6 can be either a 5.5 or 6.4, depending on the actual construction of a particular brand of turnout.
The safest solution would be to buy the brands and sizes you want to incorporate on your layout and make templates from them. These templates can then be used to trace out your track and roadbed locations to test fit them before you committ yourself to permanently glued in place roadbed.
I have found that no matter how good your track planning software is, you will still have to field fit the track. It never goes in place exactly as planned so you have to fudge a little. That is why I agree with the previous suggestion to use flex track instead of sectional. It allows you to make those minor adjustments as you lay the track. I haven’t bought sectional track in a long time but I would guess that flex track is also cheaper per foot than sectional. Another advantage is it doesn’t have that unprototypical U shaped opening in the ties at the ends of the piece of track. Instead you simply cut off the last few ties to make room for the rail joiners, then reintall those ties under the rail joiners after the track is in place. The only time I use sectional track is when I need a very short (3 inches or less) piece of straight track. I find that a sawed off piece of sectional track is more rigid and better for this application.
Another card to keep in your pocket - turnouts are not sacred. If you can cut flex track to fit a curve, you can cut unnecessary parts of turnouts off, too. Atlas turnouts in particular have 1.5 inches of straight ahead of the points. You can lop off up to an inch off that - rail nippers work great - without affecting a thing. Same for the extra length at the diverging ends. Makes all the difference in whether an arrangement will fit or not.
Of course, this trick doesn’t work with planning software unless you can go in and modify the library or trim a turnout after placing it.
Personally, I think you hit the 95% design point already, and putting in more effort on the computer is going to hit diminishing returns. Very, very few things, especially model railroads, ever get built exactly as designed. At this point, I would recommend just go ahead and layout the track using actual track pieces, starting with the tightest areas and 180 degree+ curves first. Then connect the rest with flex track, putting in gentle curves where needed. Again, don’t hesitate to shorten turnouts to make the track layout work better.
yours in tracking
Fred W
This is great stuff guys. I have been using flex track in my planning but I find that you still have to assist the software by at least getting two ends to line up somewhat near each other. For example, if I draw a 22" curve with sectional track, no prob. Try the same turn with just flex and it’s a pain. I know it’s just the software.
Jack - I noticed that about the Atlas turnouts. I do not want ‘snap’ turnouts, I was smart enough to realize I wanted custom-line only turnouts. I read somewhere that the radius is different as you stated. Where do you get xtrkcad?
Yea Fred I have to agree. I believe I am ready to start laying track - that is why I posted this topic. Wanted to know what I was doing with turnouts before I started. It’s good to know I can snip turnouts as well - I can see where that might come in handy.
I will be using all flex track where possible. I am a little hesitant as I used flex on my old layout back when flex was new and had a few problems laying it. Specifically, I had a turn with flex that was never quite right - derailment problems.
I guess the turnouts aren’t so confusing once you have an idea what you are doing. I think I really am getting the gist of it now. I only have Atlas custom-line #4 and #6 turnouts. I think that will do the job nicely. The next step is to fini***he benchwork and use templates to see how it fits in the real world. That makes sense. Thanx for all the help gang!
Xtrkcad www.sillub.com
Ken.
No matter how good the CAD program is, the only way to be sure that your track will go down as designed is to lay the components (or templates made therefrom - easily done with a copying machine) on the roadbed where they will be installed. In my experience (50 years and almost as many different layouts) there is always some variance from the original small-scale plan when the track actually goes down.
You bring up a good point about mixing different brands. Not only do they look different, the ties may be different thickness which may require shimming even though the rails are the same height.
Better get used to delays in this hobby. Recently I waited a year to get HOn30 stub turnout kits made by B-K Enterprises, but that’s not your main stream model railroading anyway.
Other than major manufacturers like Atlas, Bachmann, Kato and Life-Like, most manufacturers are small or cottage business that only do short runs of product at a time. Often they fold up and disappear and/or are bought up by someone else. Diamond Scale is a good example of that. They disappeared for a few years when they relocated under new management.
What is worse is when something is discontinued or retired. Walthers is notorious for retiring models. They’re not an actual manufacture but rather contract with manufacturers to produce products with the Walthers brand. Therefore they don’t have control of production schedules.