# Minimum Radii



## VentureForth (Dec 10, 2013)

Can someone please share practical experiences with minimum radii? Two foot radii seem to work fine for Bachmann's Big Hauler box sets, and some of the smaller pieces. Then I see big stuff from Aristocraft with minimum 4' radius. Since those are the ranges of LGB's sectional pieces that are common, do you depend on flex when using large equipment?


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## Randy Stone (Jan 2, 2008)

Aristo Craft, LGB and Piko among other make larger radius curves along with larger radius switches. Always use the largest radius curves that you have room for. Because what you have today may well operate on 2 ft radius curves, we all tend to move up to larger locomotives and cars that either don't look good on tight curves or just plain will not traverse through the tight curves without derailing. Also, remember that your frt yard or side tracks also need larger curves for long locomotives and especially for longer frt cars with body mounted couplers.


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## Totalwrecker (Feb 26, 2009)

For me minimun radius is a sales ploy 
Do you want cute trains that run around a cute layout or are you a scale modeler? 
Nothing wrong with either way, but the goals are different. 

My perspective is from the scale side, but my cute factor is sectional track instead of natural flowing flex track... following the 'scale' idea I want to use the broadest curves possible, because tighter curves cost a railroad more; more fuel to compensate for the drag and more rail because the drag wears the rails faster.... besides my equipment looks a durn site beter to me on big sweeping curves than tip toeing around tight corners... 

A sales ploy? yes, while equipment may be able to navigate the minimum, rarely does it look good (to me) doing so and it is more likely they will wear out faster. But the company sells more.... that's my take, your milage may vary... 

John


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## vsmith (Jan 2, 2008)

I recently posted this in reply to another similar question but it answers some of the questions you have asked: 

One good way to save money on track is to look for used track and switches on Evilbay, for the most part brass track is pretty hardy, so used track tends to still be in very good shape,, UV deterioration on the plastic ties can be an issue on early Aristo track but for the most part its a great way to save $$$. 

I have been indoors for years, strict R1 (4' diameter curves) use, and short rolling stock means I can get a fairly insane amount of track into a very small area. Based on the stock you mentioned you could also go R1 and save alot of space, but dont be brainwashed into thinking you MUST have 10 diameter curves or your doing it wrong. While having the widest curves is good advice, dont use them if the end result is a boring layout, the BEST curvature that fits your goals. Determine HOW MUCH AREA you have to work with, get a layout track plan going, THEN decide what curvature works best for the area you are working in. In addition to the R1 4' dia curves there are 5' dia, 6.5'dia, and 8' dia curves, all of which can be mixed and matched to create a very interesting layout in a small area. 

Now that being said, and before the "wider is better" folks start fussing, I will add this caveat, think about what your long term goals for this layout are and what you really wish you would run on this layout if you have the genies lamp and could make it happen, IOWs whats the BIGGEST thing you would like to run on this layout. will you be happy with a Piko mogul pulling short stock or do you dream of streamliners? A USA 4-8-4 Hudson? An Aristo 2-8-8-2 ? a string of heavyweight passenger cars? 80' autoracks? You see where I'm going, all of these require very substantial curves, much wider than the ones I recommended, but also they require a much greater commitment in available yard space and money to install. Decide what you would LIKE to run, determine what curvature it requires, and then build around THAT as your ruling curvature. So you need to make some decisions now that will benefit you in the long run. 

Also ...BE WARNED. Make sure whatever the minimum curvature you decide to use that the curvature of your turnouts MATCHES or is wider if turnouts are not available in that curvature. IOWs no one makes 5' dia turnouts, so you have to go to 6.5'. Sounds simple but its a very common newbie mistake to buy tracks and rolling stock that require wide radius turnouts then wonder why it derails on the R1 turnouts they bought to save money. 

Good Luck.


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## vsmith (Jan 2, 2008)

dbl post


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## chuck n (Jan 2, 2008)

I agree with John and Vic. Where are you going with your railroad. My layout in Colorado, before moving to Virginia had LGB 1100 (4'D), LGB 15000 (5' diameter) and LGB 16000 (8'd) curves. 

The 4' diameter curves were on the cog line that connected two different levels. Only 2 axle engines and cars ever ran on the cog. The lower level had the 15000 curves and I ran LGB moguls, freight and passenger cars (American style). The upper loop had the 16000 curves and I mostly ran the longer LGB Swiss RhB passenger cars. At that time I didn't have any of the longer USAt cars and engines.

When I moved to Virginia, in 1993, I built my current layout with Aristo Wide-radius curves (10' d). That was the largest sectional track available at the time. Now I wish that I had used flex track and had larger curves. My Larger engines, USA SD40-2, USA SD70Mac, USA GG1 and some others look a little funny with the large overhang on the curves, at least to me. I also run Aristo heavyweights and USAt streamliners. They handle the 10'ers, but the streamliners also hang over a lot. It is better to buy your track once, not several times as I have. My current choice would be LGB 18000 curves as a minimum and probably would go wider. They a 15-16' diameter. I am using 18000 series switches for all of my turnouts.

Chuck


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## VentureForth (Dec 10, 2013)

Perhaps this is another question for another thread, but an advantage of the sectional track is its rigidity. You set it down, perhaps nail it to a substrate, but maybe not, then ballast. How easy is flex brass track to flex without introducing kinks? Does it stay put, or do you have to anchor/nail it in place so it stays put before ballasting? Does ballast actually ballast or is it just an aesthetic finish?


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## Scottychaos (Jan 2, 2008)

I think the "rule" needs to be amended.. 

The old rule: 
"Always use the largest curves you can." 

The amended rule: 

"If you arent sure what you want to run, and you might eventually want large diesels or standard gauge steam engines, (or if you already have them) 
then always use the largest curves you can. 

But if you *know* you will only want to run trains like this: 









or this: 










then its fine to use 4-foot diameter curves." 

You have to know what kind of trains you want to run first..then plan your curves accordingly. 
then you wont be surprised by this concept later on: 









 

There *are* people who dont "get that"..until its too late. 
then they try to blame the manufacturers for making trains they cant use.. 
which is of course not where the blame belongs.. 

Scot


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## wgn4884 (May 23, 2013)

What others are telling you is definitely true. As far as realistic appearance, the bigger the curves the better, unless you are doing something like a logging road and want to see the train snaking through tight curves. I have some big passenger cars, over 35 inches, and they don’t look realistic even on 16 1/2 foot diameter curves. They operate fine, but just don’t look great. But appearance is a matter of personal taste. Sometimes it is possible to use tighter curves in the “background” and wider ones in the foreground. Also, easement curves can help appearance by eliminating the sudden transition from straight track. But easement curves take more room. 

Another thing to consider is clearance between tracks if you are thinking of double track. I used some 4-foot and 5-foot curves on the same center. 14 1/2 inch cars are fine, but I can’t run even 17-inch cars there because of the overhang.


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## Totalwrecker (Feb 26, 2009)

Posted By VentureForth on 16 Jan 2014 10:14 AM 
Perhaps this is another question for another thread, but an advantage of the sectional track is its rigidity. You set it down, perhaps nail it to a substrate, but maybe not, then ballast. How easy is flex brass track to flex without introducing kinks? Does it stay put, or do you have to anchor/nail it in place so it stays put before ballasting? Does ballast actually ballast or is it just an aesthetic finish? 
Everything gets discussed in the Beginners Forum! 
Don't confuse our 'flex' with track that is flexible. Best results are achieved with a Rail Bender, which mechanically rolls the rail to a curve which the metal holds.

Some folks 'belly bend' their track for a more folksy look of a wandering branch line. I repurposed 8'D curves to nearly straight for sidings, by belly, knee and crescent wrench (at ends). I started with an S curve so the outer ends matched. 

Metal tends to flex back a tad as it is bent, if you go past the angle you want a tad you shouldn't need to use spikes to hold the shape. Metals tempered to 'dead soft' can usually skip this.

I use ballast and if you use broken, rough stone it will lock together and hold quite well. Smooth stones will wander off and many migrate down with out a hard subsurface or a barrier such as weed block.

I use SS, I make sure the rails are together and the screws through the joiners are torqued tight, the whole layout grows and shrinks through heat expansion, my straight aways are modest; 10 -20 feet and my temps range from 14F to 114F, track laid in 80sF, still waiting for my 1st kink.

Happy Rails.

John


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## Ted Doskaris (Oct 7, 2008)

Coupler types are of consideration, too, with standard truck mount "hook & loops" best for really tight curves - like when a short length train is going around the Christmas tree or when making sudden directional changes. 
However, for any scale like operation with long length trains, hook & loops are ugly, and body mounted knuckle couplers work best for larger diameter curves (8 foot diameter or greater). 

As to changing track directions ("S" bends), it's best to allow for a straight section transition between - about the distance of the longest car (or loco) you intend to use. This avoids pulling cars off the track when using knuckle type couplers. 

-Ted


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## VentureForth (Dec 10, 2013)

All great information. I appreciate all your patience. So, back to the radius and stock sectionals for a moment. When I look at something like Aristo-Craft's SD-45, they say that it has a minimum of an 8' diameter curve requirement. I can probably manage that, but IF I want to double track, what do I do? Can't go inside because it would be too tight. Are there sectionals greater than 8' D? What is the recommended track spacing for double track?


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## chuck n (Jan 2, 2008)

To add to Ted's comment. Truck mounted knuckle couplers will work on tighter curves than body mounted. I have put Kadee truck mounted knuckle couplers on a number of my cars. I use Kadee S31. This coupler has an off set shank which brings it up to the height of body mounted couplers. I chose those for cars that would have required surgery to put on body mounted couplers. In most cases these are LGB cars. I do not like to cut pieces off a car unless it is absolutely necessary. Another disadvantage to truck mounted couplers, it is difficult to back up a longer train through tight curves and keep the cars on the track. Chuck


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## CliffyJ (Apr 29, 2009)

Just a side note about flex track. When I was in the data-gathering stage like yourself (not long ago), flex seemed mysterious / indeterminate. But after laying a lot of it last year, I have to say that once you get the hang of it, it's a lot of fun. Though you do have to get a Dremel-like cutoff tool (my $30 knock-off works fine) and a dual rail bender, the benefits are many. More realistic appearance, gradual transitions, any radius you want, and (I think) cheaper. One good source is Train Li, they have brass and nickel plated. 

Cliff


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## vsmith (Jan 2, 2008)

Posted By VentureForth on 16 Jan 2014 02:59 PM 
All great information. I appreciate all your patience. So, back to the radius and stock sectionals for a moment. When I look at something like Aristo-Craft's SD-45, they say that it has a minimum of an 8' diameter curve requirement. I can probably manage that, but IF I want to double track, what do I do? Can't go inside because it would be too tight. Are there sectionals greater than 8' D? What is the recommended track spacing for double track? 
8' inside, 10' outside? That gives 12" center to center between track, most stuff will run of that but the larger stuff (heavyweights, autoracks) may have overhang fouling issues, this is why most folks who build larger layouts prefer using a track bender and custom bending the curvature, then they can get 16" center to center which is better, or whatever they need.

...as for sectional track I do believe that 10', 12' 14', 16', 20' are (or were) available.


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## BigRedOne (Dec 13, 2012)

Flex track offers some additional advantages, beyond custom radius and smooth entry and exit. 

It is longer, usually six or eight feet in large scale, which means fewer joiners. Each joiner is a potential electrical failure, or place for the track to separate. Flex also can allow staggered joiners, which is the prototypical practice. 

If you've yet to acquire much track, you may find it worthwhile to do some homework beforehand, and invest from the beginning in a solution which will satisfy your longer term objectives. 

After a year with my large scale on the floor, I finally began constructing a railway. I'm keeping mine modular, which enabled me to begin in stages even without a final plan. I want something portable, which I can reasonably move from my basement to the outdoors, and perhaps take to a show. I'm going to try for about 12 foot radius (24' d); since I know I want to run live steam, and aluminum track is about half the cost of brass, I'm leaning toward aluminum flex.


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## Dan Pierce (Jan 2, 2008)

For a small circle to run small engines and cars, I bent a pair of 8 foot rails into a circle. Came out ot about 29 inch diameter. 
Great portable layout as there are only 1 clamp per rail, no power losses, nothing to separate for trains to derail. 
Works for me and I run FRR cars with small 2 axle engines. 

Next is 2 pair of 8 foot rail to give more than 4 foot diameter circle and only 4 clamps total.


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## Ted Doskaris (Oct 7, 2008)

A 29 inch diameter layout would be great to put on a night stand with lamp at its center next to your bed. In the morning you could have a timer turn on the lamp and run the train with whistle to wake you up! 

-Ted


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## BigRedOne (Dec 13, 2012)

Though you risk a derailment groping for the snooze button!


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## TJH (Dec 27, 2007)

Posted By VentureForth on 16 Jan 2014 02:59 PM 
All great information. I appreciate all your patience. So, back to the radius and stock sectionals for a moment. When I look at something like Aristo-Craft's SD-45, they say that it has a minimum of an 8' diameter curve requirement. I can probably manage that, but IF I want to double track, what do I do? Can't go inside because it would be too tight. Are there sectionals greater than 8' D? What is the recommended track spacing for double track? 
As others have said, with double tracks you need to be careful of your side clearances. If you're running some of the narrow gauge stuff in 1/22.5 or 1/20.3, they require much wider clearances, and if you do run a tight radius turn, the pilots on some of these steamers can really hang out. All of our stuff is LGB and Bachmann 1/22.5, then we got a couple of 1/20.3 engines, and we had to take a hammer and saw to a lot of scenery because the locomotives did not have sufficient clearance. We also had to space out tracks in the yard so the trains could sit next to each other and pass.


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