# Rail gauge NMRA BUT I think its too tight on curves



## DavidJones (Nov 21, 2019)

The track I've laid is mainly Bachmann EZ track with some Kato turnouts and some flexitrack. I have worked on it a year and I'm barely at the stage of a 9yo on Christmas morning- I can get it to run in A complete circle.

Otherwise I spend hours after hours working on trying to get the trains to stay on the track. 

I've VERY carefully observed. Part of the issue is that little of my track is on a flat surface. I've very carefully evened out the track so there are no quick slope changes and everything is co-planar. (ie flat- both rails, and parallel).

STILL it derails. Often on curves. My test locomotive is a Kato E9A. But I try all my others on it.

What happens is the truck (of six wheels) goes around the curve until one wheel 'pops' off. Then, its game over until it gets to a rerailer (I have 8 installed). I have a NMRA gauge, and everything is within the normal.

I'm thinking that I need to have the rails slightly further apart than the gauge suggests in curves. If you think about, say, a chalkboard eraser going through a straight set of tracks exactly the right distance apart, then you put it into a curve and it doesn't fit anymore (there is a gap in the middle of the eraser between the tracks on the inside of the curve, and the outside corners are wider than the track).

Basically it pops the trucks upwards and it derails. 

I'm sorting out how to move the tracks maybe a half a mm further apart. 

Am I right in the geometry issues? My track has a minimum radius of 11.5, but most is 121/2" radius.

My current plan is to make a bunch of rectangles just very slightly wider than the gauge on the table saw. Then wedge them in between the rails. I'm thinkiing of trying a heat gun to loosen up the track and plastic junction just a bit, then using some superglue in tiny dabs to hold them in place.

Any thoughts or ideas? I know the axles are supposed to move laterally in the trucks slightly to conform to the curve, but it doesn't seem to be enough. I have 8 locomotives and all but the eight wheel switchers have the same problem (the steamers I expected it with).


Train is, btw, on a door that has been expanded a bit sideways and has the blue styrofoam on it. The tracks are adhered with silicone caulking (it holds them very well and they can be easily ripped up if needed (they all need it eventually). Somehow each of my kato double crossovers are perfect and never cause derailments.


Thanks for any advice or thoughts


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## CTValleyRR (Jul 26, 2014)

The general rule of thumb when troubleshooting problems like this is that if everything derails, it's a track problem, if one thing derails, it's a loco problem.

You shouldn't have to fudge the rails like you're talking about. If the track is properly gauged, then that's not the issue. Bachmann N scale track is reportedly a little under-gauged, but if you've checked it, then it should be ok.

Have you checked the locos wheels for proper gauging? Do the trucks swivel freely? Can the loco rock side to side kn the trucks? These are all things that might cause this behavior.


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## traction fan (Oct 5, 2014)

*Kato locomotives & track*



DavidJones said:


> The track I've laid is mainly Bachmann EZ track with some Kato turnouts and some flexitrack. I have worked on it a year and I'm barely at the stage of a 9yo on Christmas morning- I can get it to run in A complete circle.
> 
> Otherwise I spend hours after hours working on trying to get the trains to stay on the track.
> 
> ...


David;

In my opinion, you should definitely NOT widen the distance between the rails (aka the "gage" of the track.) Unless it is too tight for the NMRA gage to fit through it smoothly. In that case, your "heat (perhaps with a soldering iron on the rail, or cut off some of the molded plastic "spikes" A heat gun is pretty drastic!) and then widen" idea would be needed. If the gage does slide through the track smoothly, then widening should not be necessary, and it may cause problems itself. 
On the "Track" edge of your NMRA gage there are two projecting points that, as you now probably know, are intended to slide easily along the inside surfaces of the two rails. One of those projecting points has a "step" in it. The point should move along the inside of the rail, but the stepped part should not fall in between the rails. The two points are the minimum distance that should be between the rails. The tiny extra distance between the main point and the step is the maximum distance that should be between the rails. The standard is strict, it's not a "suggestion." Having too much distance between the rails can be just as bad as not having enough distance. It can cause derailments too.

You mentioned a Kato E-9 locomotive. That's a great model, I have several of them. However Kato, a Japanese company, does not always set the wheel gage of it's models to American NMRA standards. They tend to have their wheels a little too close together to fit the "wheels" notches on an NMRA gage. Often they need adjustment. Have you checked the wheel gage on this loco, and all your other rolling stock? Kato makes excellent quality products and I'm a big fan, but they do "march to the beat of a different drummer.", in fact, they have their own rhythm section. 

You also said your minimum radius was 11.5 inches. That may not be big enough for an E-9, or other six-axle diesels. (and mid-to-large size steamers) 
I had something similar happen to me. Most N-scale cars and locos are able, at least theoretically, to operate on 9-3/4" radius curves. Some longer cars and locomotives are recommended for 11" or larger radius curves. I initially adopted a 12" minimum radius for my layout, figuring that would be big enough to handle anything in N-scale. Wrong! Later I bought two of Kato's beautiful 2-8-2 Mikado steam locomotives. They had 11' as their recommended minimum. Well, they derailed more often than I was prepared to put up with on my 12" curves. I did some real world testing with various curve radii, and found that 16" radius was the curve where they actually stayed on the track reliably. So, I ripped up my 12" radius curves and laid down 16" radius. Now things work well.
An E-9 is a pretty big locomotive. If you are going to stick with an 11.5" minimum radius, I suggest using four-axle diesels and small steamers with no more than six drive wheels. I would also suggest adding "easements" to the entrance and exit of your curves, and to the top and bottom of each grade.

good luck;

Traction Fan :smilie_daumenpos:


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## DavidJones (Nov 21, 2019)

I'll check the wheel gauge tomorrow and get back to you.

I did move the rails slightly apart in some of the most troublesome areas. It seems to have fixed it.

I made blocks of wood carefully on the table saw. I'm impressed with this model train thing that we are really often talking about fractions of a mm.  My table saw is excellent quality, but some of the blocks were very, very slightly wider (micrometer said .13mm different). So generally I used the thinner ones (it was easy to make a few hundred of them out of a foot long piece of hardwood). I'd slide them down in the straight sections into the curve (making sure that they contact only the top of the rail). I waved the heat gun over it a few times (I didn't really want to melt much), then put a tiny drop of superglue between the metal track and the plastic nub that comes up from the railway tie. My biggest problems were in areas that connected to flex track. If they were worse, I think I'd melt the solder joint and introduce a tiny gap on the outside rail to move the rails further apart.

Anyways, so far so good. I do use the track gauge constantly. I sight along and perpendicular to the rails- if they're not in the same plane, then boom, off she goes. I suspect a quarter of a mm too tight wedges the trucks up, but I think they could handle 1.5-2 mm too wide before anything could fall in between.

I started with the bachmann track, added EZ track on some of the sweeping curves etc. There is Kato in there (the double crossover and a few turnouts). I've slowly had to remove the flex track sections. Just too fussy. I did get a deal on some Kato curved bridges- 12 3/8" radius. I replaced an elevated area of track with it- that section of track is a reversing loop. The only problem with it is that the inside 'rail' of the girder hits the passenger cars when they go by. I'm trying to think of a clean way to cut the girder height down.

I'm really hoping ballasting covers much of my track mess. The different kinds of tracks, the messy junctions etc.


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## DavidJones (Nov 21, 2019)

*I forgot to give credit*

to the idea of filing the top of the track so that the inside is a bit lower (ie the top of each rail would form a v if the lines were connected). I think it does the same thing, and is probably neater. 

I could get the kato six wheel trucks to work on 95 plus percent of the track before. I'm still hopeful that enough fiddling will get er around. I love some of the big steamers of the 30's and 40's. I think I have a route around the outside with a minimum of 16" radius that I could run them on. If not, then I'll be ripping up more track and putting the flextrack back down


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## Dennis461 (Jan 5, 2018)

Does your track look like this?


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## DavidJones (Nov 21, 2019)

Not sure exactly in which way, but not really- the only pieces of flex track in there are made from one piece, without joints. They join the bachmann ez track often. I've had to file down the insides of some of the track joiners to keep them from lifting the wheels


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## DavidJones (Nov 21, 2019)

and all joints are soldered


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## baldwin (Oct 28, 2019)

Very new to MRR and have been reading a lot before really digging into a setup of my own. The curve radius really stands out as the fault. Of course your space depending, I've read a few times 18" radius is the preferred minimum for N, but I've read others using smaller.

I wish you luck in your troubleshooting. Frustrating indeed.


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## DavidJones (Nov 21, 2019)

*Having much more luck today*

Between the glueing of the rails separated ever so slightly, grinding down some of the inside rail joiners (ANYTHING on the inside of the rails causes a problem- tiniest bit of solder, joiner that sticks up just a touch etc), and filing the tops of the rails into a v. I have one (yup, ONE) complete loop that the six wheeled trucked locomotives run around. Low and high speed. Which is, hopefully, telling me that with similar care I can make it work on the other loops/loopets. 

Just wondering what you do if you find the wheels of your locomotive out of NMRA spec? Can they be adjusted, do you get a new set of wheels/trucks/locomotives?

Thanks everyone for their help.

Next issue is stopping the locomotives from losing contact with the rails. I've polished the track (literally) so you can watch the sunrise on it. The wheels are clean. I've checked to make sure all the track is parallel. Some locomotives still lurch. A bit more likely in one section of track that is under a bridge (and hence, more difficult to polish), but anywhere. And they'll most of the time run under there. 

Thanks everyone for their help


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## CTValleyRR (Jul 26, 2014)

baldwin said:


> Very new to MRR and have been reading a lot before really digging into a setup of my own. The curve radius really stands out as the fault. Of course your space depending, I've read a few times 18" radius is the preferred minimum for N, but I've read others using smaller.
> 
> I wish you luck in your troubleshooting. Frustrating indeed.


18" is the preferred minimum for HO, not N.

In N, as Traction Fan said, it's 9-3/4".

But this is just a guideline. Many locos and cars --- especially those with longer trucks or more axles -- need broader curves than that minimum, and ever the manufacturer's recommendation isn't a sure bet. The only way to know for sure is to test run it.


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## DavidJones (Nov 21, 2019)

Getting much success!!!!! Not quite there, but very close. 

What I've learned-

The tracks must be parallel on a vertical plane coming off of a curve. The superelevations (which I did slightly- nothing more than a paper match thickness on the outside) blending into straight track is the biggest problem. The train is like a square table at a restaurant that wobbles. The high leg (ie, the front truck) only makes contact on, say, the outside of the curve. So it can deviate towards the inside easily.

I suspect this is where the easements come in. Obviously, to get the superelevation flat, there has to be a twist somewhere. Putting the somewhere in an easement, with less of a curve and a long distance to reach parallel probably keeps it on the track.

My tracks WERE often too close together. I understand the flextrak doing that, but the Bachmann EZ track? Maybe I've just plain messed with it too much. The wood spacers, superglue and white glue have ensured that the space between the tracks is on the wide side of the NMRA guidelines. 

Now I'm having trouble keeping contact through the whole line (ie, not having it stall). I've been cleaning and polishing track, cleaning and cleaning loco wheels. Used nail remover on the tracks. I'm thinking this is more of an elbow grease problem

Thanks for everyone's help!


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## cv_acr (Oct 28, 2011)

A paper match is actually a relatively thick piece of cardboard. Rather than "slight", that's a little excessive for superelevation for N scale, and if you're just going from "zero" to "paper match" without any gradual transition you've probably introduced a fairly significant unevenness to the track there. That's going to cause issues.

I'm afraid I don't even remotely follow what you're doing with the wood spacers, superglue and white glue to "change the distance between the tracks"...


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## DavidJones (Nov 21, 2019)

*In followup*

I have almost all the track 'fixed'.

The problem was, as I suspected, that the space between the rails was too narrow- up pop the wheels and off it goes. Once I got that fixed, the big locomotives have had no problem.

Only in one place did I get to a point that the rails were too far apart.

Looking backwards, I think most of the time I ended up replacing the narrow rails.

The little wood blocks were invaluable for that though. One of the primary problems is that the flex track on curves could get too tight on the outside (yes, I did cut them to different lengths). Relaying that flex track, I put the wooden blocks in between the rails as I was laying it- it prevented the outside rail from pulling in. 

I did, in some places, stick with my original idea- a very light touch with the heat gun to loosen the little plastic pieces that hold the rails to the ties, wedging in the blocks while it was warm, and then supergluing the tracks down to the ties until it was dry, then removing the blocks. It works. It is, I think, that the areas where I had done that initially were just too messy, and having the track sitting there I ended up just biting the bullet, cut the old track out and then replaced it as above.

Now down to figuring out the short (I think it comes from replacing track that had had a space cut between them to block the electrical path and not noticing it and putting in solid track)

One useful thing I learned. Superglue doesn't dry like on TV. It really gets its full strength after 24h have passed. I can speed it up a bit- I let it dry for say 15 minutes, then leave a hair dryer on 'warm' on it for maybe 30 minutes, then let it cool. Then its hard enough to hold things like the styrene spacers in the rail when they're being filed down.

Thanks everyone!!!!


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## traction fan (Oct 5, 2014)

*Heated super glue*



DavidJones said:


> I have almost all the track 'fixed'.
> 
> The problem was, as I suspected, that the space between the rails was too narrow- up pop the wheels and off it goes. Once I got that fixed, the big locomotives have had no problem.
> 
> ...


 David;

First of all, congratulations on fixing your own problems, in your own way. Heating super glue can release toxic, eye and throat irritating fumes. Be careful. It would be a shame to hurt yourself, especially after coming so far. 

Again, congratulations;

Traction Fan :smilie_daumenpos:


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