# Track Spacing - Straight into Curve



## NicholasLEby (Apr 21, 2016)

Hey all, wondering if someone could offer me some help. I'm new to track layout, so hope this isn't a silly question. I'm going to build a shelf around the perimeter of my office to have 2 tracks for HO Metra trains to run on. I'm having trouble figuring out how to make the curves/straight work.

I want the straight track to be 2" on center, and the curves (22.5") to be 2.5" on center. More distance of curves because the metro bi-level passenger cars are longer.

How do I transition from 2" center to 2.5" center in curve then back 2" centers?

Attaching the image of track software i'm playing around with.

Thanks so much for any help! - nick http://www.nleby.com


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## MtRR75 (Nov 27, 2013)

For one thing, the outer curve must be a larger radius than the inner curve. If your inner curve is made from 22.5" radius track, and the distance (center to center) between the two curves is to be 2.5", then the outer curve should use 25" radius curves.

The easiest way to get what you want is to use flex track. That will make it easier to get the two different curves lined up. Then use a longer easement between straight and curved for the outer track (than for the inner track) -- to achieve the wider spacing on the curve.


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## lajrmdlr (Apr 25, 2014)

Also using flex track the change from straight to curve doesn't have to be so abrupt. Flex will form a natural spiral curve before the real curve. The prototype RRs do this so the cars & locos don't "whip" into the curve at speed.


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## mesenteria (Oct 29, 2015)

I agree, it's best to use flex track, but it would be best to use it on both curves. If you elect to stick with sectional track segments, you'll have to build the spacing between them well before the onset of the curvature. A short length of flex can accomplish the slight curve away from each other.

I advise you to mock it up first by tacking down the tracks with nested curves. Then, run your longest equipment and the engines with the greatest overhang at their ends to see how close you can get the spacing. Get some hard numbers working for you, and some confidence. In fact, once I have it mocked up and proven, I make a template of the minimum spacing, usually at the apex of the curves, with a small slab of scrap plywood. I mark the tops of the rails with chalk or something, tap the ply onto the rails, and then cut shallow grooves where the chalk indicates it made contact. Later, I can slide those grooves around the curves and feel for binding that is of the type where the tracks are too close.


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## santafealltheway (Nov 27, 2012)

Maybe this well help, I have a similar corner.

I agree with the others, go with flex track.

also, if you wind up with a rail join in the corner, solder those two tracks together while they are laid out STRAIGHT, then bend them


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## mesenteria (Oct 29, 2015)

If this person doesn't know how to lay flex along curves, it's fairly involved, unfortunately. For one thing, due to the sliding rail problem, the joiner soldered on while the two lengths are aligned tangentially on a bench won't want to stay between the ties where it was soldered when you go to impart the curve to the new longer length. 

I tack down one length curved, leaving the sliding rail to fall where it wishes. Then, I take the second length, slide its rail to accommodate the slid rail, and join the two lengths, driving the protruding length into the tiny spike heads. It usually involves clearing the spike heads on at least one tie where the two ends meet so that the thickness of the joiner can be accommodated under the rails. Once everything is in place and both rails tacked into a nice continuous curve, I solder the joiner there. You can leave the track nails in place, or previously have spread some acrylic latex caulk thinly over the centerline and just leave the nails there until the caulk sets.

Those are nice curves, Jim.


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## 3.8TransAM (Jan 13, 2016)

santafealltheway said:


> Maybe this well help, I have a similar corner.
> 
> I agree with the others, go with flex track.
> 
> also, if you wind up with a rail join in the corner, solder those two tracks together while they are laid out STRAIGHT, then bend them


This is by far the easiest, especially for folks without lots of experience.

Most I know with experience do this as well. Unless it is somewhere easily workable.


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## NicholasLEby (Apr 21, 2016)

Thanks all! Looked up easements, found some nice equations to figure it. Does this look right?? Again appreciate all the help, you guys are awesome.


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## mesenteria (Oct 29, 2015)

Nicholas, the flex track will fashion a very close approximation of a cubic spiral, the proper term for an easement, if you merely fasten the ends on your centerlines and let it curve as it will between those extremities. It's the great beauty of that type of track.


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## Chip (Feb 11, 2016)

I'm no "mathmagician" so I just "stack" em into the corners, 24", 22", 18", 15" and they come out just FINE, straight in and straight out! Looks SWEET with four abreast "comin round the mountain" and suchlike!


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## mesenteria (Oct 29, 2015)

Nicholas, that should be fine, provided you don't go below your gotta-have-it-or-bust minimum radius on either of the two curves. If you can map it out accurately in scale, and draw an accurate centerline, and lay the track commensurately, you will be fine if your minimum curvature radius is somewhat above the minimums for your largest rolling stock.

To illustrate what I mean, I have a Sunset Models HO brass Canadian Pacific 2-10-4. Sunset tells us it can negotiate a true 30" minimum radius. I believe them, but so that I feel better with 'cheap' insurance, no curves on my layout can be less than 10% over that, mostly to ensure I can run at track speed and not have an unacceptable rate of derailments there. So, 33" is my minimum. This all sounds a bit painstaking, and it is! However, the more we fudge things, or hurry them, the less satisfying is the result for toy trains. Doing the hard stuff up front, and doing it well, means years of enjoyment ahead.

Learned that the hard way.


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## Chip (Feb 11, 2016)

mesenteria said:


> Nicholas, that should be fine, provided you don't go below your gotta-have-it-or-bust minimum radius on either of the two curves. If you can map it out accurately in scale, and draw an accurate centerline, and lay the track commensurately, you will be fine if your minimum curvature radius is somewhat above the minimums for your largest rolling stock.
> 
> To illustrate what I mean, I have a Sunset Models HO brass Canadian Pacific 2-10-4. Sunset tells us it can negotiate a true 30" minimum radius. I believe them, but so that I feel better with 'cheap' insurance, no curves on my layout can be less than 10% over that, mostly to ensure I can run at track speed and not have an unacceptable rate of derailments there. So, 33" is my minimum. This all sounds a bit painstaking, and it is! However, the more we fudge things, or hurry them, the less satisfying is the result for toy trains. Doing the hard stuff up front, and doing it well, means years of enjoyment ahead.
> 
> Learned that the hard way.


Etch this post in STONE, it is "TRUTH"!:smilie_daumenpos:


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## NicholasLEby (Apr 21, 2016)

Hey guys, thanks for all the help! I tried the "connect flex track to tagents and let the flex track curve itself" method, not sure it's enough curve though? Am I doing this right?


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## NicholasLEby (Apr 21, 2016)

santafealltheway - can you elaborate on your method


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## Chip (Feb 11, 2016)

Tacking them down at each end and letting the flex flex between the two points is a good way to do it. I've got sectional but not a lot of it so I'm laying sectional, tracing a line, pulling it up and laying the flex along that line.


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## CTValleyRR (Jul 26, 2014)

Actually, you need to lay the center of the curve at the desired radius first, then let the track spring naturally to the tangents. The way you're doing it, you could get some very tight radius curves. It's also not tangent at the ends. The arc of the curve exceeds 90 degrees.

Also, from your photos, I wonder if those cars will even roll on the curves from all the friction. More importantly, it looks like if the cars were coupled to each other, one would get pulled of the track or uncouple.


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## santafealltheway (Nov 27, 2012)

NicholasLEby said:


> santafealltheway - can you elaborate on your method



For the outer loop i used a track setta, then i used a lego brick to space the cork for the inner loop lol

the inner loop is more or less just eyeballed. 

I first laid down just the track with a few nails, traced the outer edges with a marker, then pilled the track back up and laid my cork.

track setta was definitely worth it

I believe i used a 28" radius tool..

I don't foresee needing it again, I've pretty much just been eyeballing it since the second corner.


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## mesenteria (Oct 29, 2015)

You have quite a bit more spacing than you need at the apexes of the curves, but that may be what you have to live with in order to get the tightest usable curvature at those apexes. It's a trade off.

You could let the inside radius stay as it is if the rolling stock like it, and then fiddle with getting the outer apex a bit closer, letting the easement take a slightly different configuration. Play with it. Right now, though, playing with it is pretty much just for cosmetic purposes or for giggles.

As suggested above, pin the apex of the outer curve maybe 5/8" closer to the apex of the inner and stretch out the extremities of the flex along their tangents to see what effect that has on the rolling stock. You may find that it doesn't mind the tighter radius.


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## santafealltheway (Nov 27, 2012)

My bad! I lied lol. It wasnt a track setta, the one i have is by "ribbonrail"

If you think this radius would work for you, I'd be happy to send you my tool. I don't need it anymore.

PM me your address if you're interested.


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## santafealltheway (Nov 27, 2012)

Just thought i'd leave a picture since i mentioned using the lego brick.


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## NicholasLEby (Apr 21, 2016)

santafealltheway - haha that's awesome. You guys have been great. Found the below reference and came up with my measurements below. Should be enough space between my tracks at curve apex at 2.5".

Thoughts guys? Will have to print this out to trace.


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## santafealltheway (Nov 27, 2012)

NicholasLEby said:


> santafealltheway - haha that's awesome. You guys have been great. Found the below reference and came up with my measurements below. Should be enough space between my tracks at curve apex at 2.5".
> 
> Thoughts guys? Will have to print this out to trace.


2.5 should be okay, thats what mine worked out to with the lego lol


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## Chip (Feb 11, 2016)

2.5" excellent! I am about to lay some track this very day and was thinking of asking the forum what a good spacing on the curves would be. I THOUGHT 2.5" might be "correct" and so it is!


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## mesenteria (Oct 29, 2015)

Hate to wag my finger, but...2.5" may indeed be okay. Might be.

Could possibly be.

How would you determine what will actually work?

Lay nested curves and do trials with your rolling stock. Mocking it up and finding out what you can get away with will be one of the best and most thankful uses of your time BEFORE learning you have to rip up your nicely laid curves.

Just a suggestion. :smokin:


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## Lemonhawk (Sep 24, 2013)

The Lego method I think ended up 2.5 inches inside rail to inside rail. Nicholas ended up 2.5 inches center to center. So Nicholas has the track a little closer. If you have some really long passenger cars it may be close.


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## santafealltheway (Nov 27, 2012)

Lemonhawk said:


> The Lego method I think ended up 2.5 inches inside rail to inside rail. Nicholas ended up 2.5 inches center to center. So Nicholas has the track a little closer. If you have some really long passenger cars it may be close.


Yessir, it was actually 2.5 from tie edge to tie edge.

Though depending on your turn radius that may not be enough if you run anything super long.


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