N-SF?

[Rhubarb Loop]

Hello,

I hope this is the right place to ask this question, but with Martin Wynne being the main peddler of the OO-SF standard I’m hoping it will be?!

I’ve been collecting various bits of American (Maine Central) and German (GDR Deutsche Reichsbahn) N Scale over the past couple of years as a diversion from my usual stagnated 2mm Finescale modelling. My model railway plans always end up being too ambitious and I move on to pondering something else before making any real progress. However, for the past 6 months I’ve been getting very close to coming up with something that feels like it might go somewhere.

Thunderbird II as I’ve dubbed will be a 1500mm long “vicarage study” proscenium arch box with fold out 750mm staging train tables roughly 640mm in diameter at each end. The box will be able to take various modules, perhaps 2mm Finescale, perhaps American N, etc. The idea being that I’m constrained by the 1500mm length, so it can’t get out of hand, and when I suddenly find myself more excited by say the Southern’s withered arm, than the Reichsbahn in Thüringen, I can swap the module out and dabble with that project for a while.

Anyway, I digress. I was originally intending to keep it simple and not bog myself down like I have done in 2mm Finescale and use Peco Code 55. However, while I think it doesn’t look too bad “in the flesh” I’ve noticed it’s not a patch on Code 40 handbuilt track in photographs. Most importantly perhaps, I don’t like the clunk / drop as the wheels pass over the nose/frog.

I really don’t want to get distracted by fs160. I’d love to be able to run newer RTR Atlas / Fleischmann etc pretty much out of the box, with just the odd bad example wheels having to be tinkered with.

As far as I can tell the European FiNeScale N is just hand built track NEM standards using Code 40 rail? I was wondering, has anyone considered adopting the OO-SF approach of narrowing the gauge so that even better looking track can be produced with RTR wheels? Is there a mathematical approach to working this out based on NMRA / NEM wheel standards, or so I have to just build something and see if it will work?

I’d love to hear anyone’s thoughts!

Cheers,

Alex

 

[Martin Wynne]

Hi Alex,

Welcome to Templot Club.

Creating a N-SF set of standards will require knowing:

1. the NMRA track gauge.

2. the NMRA flangeway gap.

3. the NMRA wheel flange thickness.

4. the NMRA wheel width.

Those things should be easy to know, but they are not. Or at least they weren't 10 years ago, see:

https://85a.co.uk/forum/view_topic.php?id=1334&forum_id=1

which covers the subject of the N Gauge standards. Things may have changed since.

p.s. I'm not a peddler of 00-SF. After rashly including it in the Templot pre-sets 20 years ago, my only ever intent has been to explain it. Over and over again to some folks on other forums -- sometimes I wish I had never mentioned it. It makes no difference to me what standards anyone chooses to use.

cheers,

Martin.

 

[Rhubarb Loop]

Hi Martin,

Thank you for the welcome!

One of my favourite quotes relating to model railways is by Henk Oversloot of fs160 - "standards only exist to be able to say that you do things differently!"

I'll have a read of the link you've shared directly, but to answer your question, these are the published N Scale standards that I'm aware of:

NMRA Standard Track Standards - https://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-3.2_2010.05.08.pdf
NMRA Standard Wheel Standards - https://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-4.2_2019.01.04.pdf
NEM Track Standards - http://www.miba.de/morop/nem110_d.pdf
NEM Wheel Standards - http://www.miba.de/morop/nem310_d.pdf

Track Gauge = 8.97 NMRA Min - 9.0 NEM Standard 9.02 NMRA Target - 9.12 NMRA Max - 9.2 NEM Max

Flangeway Gap = 0.68 NMRA Min - 0.71 NMRA Target - 0.76 NMRA Max - 0.8 NEM Min - 0.9 NEM Max

Wheel Flange Thickness = 0.5 NEM Min - 0.51 NMRA Max - 0.6 NEM Max

Wheel Width = 1.83 NMRA Nominal - 2.0 NEM Min - 2.2 NEM Max

It's amazing how the European's seem to be very sloppy with their standards compared to the Americans?

I'm glad you got the humour in my post about 00-SF. It sounds like a great concept, and if I was a 4mm scale modeller looking to take advantage of the array of quality ready-to-run I think it's a no brainer if you want better-looking track but can't justify the time of converting everything to EM/P4. Well, that's the reason I'm keen to explore N-SF I suppose!

Cheers,

Alex

 

[Rob Manchester]

Hi Alex,
00-SF is popular because it looks better ( and runs better ) than normal variants of 00. Most everything RTR from the last 20 years will have suitable wheels and back-to-backs are usually fine. People can buy locos and stock and put them on nice hand laid track and when they want to move on they put them back in the box and sell them. You just have to bear in mind that buying older second hand items may mean some work is involved to get them running on 00-SF.

I model ( mainly!) in EM-SF because I like converting loco wheels and the track looks better than standard EM. If I am not keen on particular items I try and get rid of them before I start any conversion work.

I sometimes look at N gauge locos and think maybe one day but the variety of wheels fitted to them could mean work would need to be done to bring them up to modern standards. Maybe the finescale 2mm society could give you some ideas - I think they do replacement wheel sets for locos.

Rob

 

[Martin Wynne]

Hi Alex,

The MOROP and NMRA standards for N Gauge are not compatible.

I'm afraid if you want to mix models from both sources there is no scope for an N-SF standard. The only dimensions which will accept both are:

check gauge: 8.2mm MIN.

crossing flangeway gap: 0.9mm.

track gauge: 9.1mm MIN

The problem is that MOROP allows a minimum back-to-back of 7.4mm. That means the check span cannot exceed 7.3mm for a running clearance. Subtracting that from the check gauge (8.2mm minimum for NMRA wheels) makes the crossing flangeway 0.9mm. With symmetric flangeways you then have a minimum track gauge of 9.1mm.

The only way you could get the track gauge back to 9.0mm is to have asymmetric flangeway gaps, which is a no-no if you want to create diamond-crossings and any pointwork more complex than a simple turnout.

If you were to restrict to models from one or other source but not both, it might be possible to find a tighter standard. Otherwise it would be necessary to adjust some back-to-backs where needed to use tighter dimensions than above.

cheers,

Martin.

 

[Rhubarb Loop]

Hi Rob,

I'm a member of the 2mm Scale Association and regular dabbler. I enjoy the track building, but I really was looking for something that involved a minimal effort in improving the wheels of locomotives and rolling stock, so that I didn't get bogged down in conversions. Tweaking the back-to-backs, maybe the improving the flanges on an older model, that kind of thing only. When looking at photographs or videos of N Scale layouts from around the world, it's always the track that can immediately betray it as a model, not the wheels that are often lurking in the gloom.

Martin,

I guess it was naive of me to assume that a common improved N Scale standard could accommodate both US and European rolling stock, especially when the two are quite amazingly different. However, I don't plan on running US stock in Germany, or German stock in the US so there's no real reason why I can't adopt different N Scale standards in the same way that I'll be continuing 2FS for my British projects. The only interoperate requirement is that they can all run on a staging yard laid to 9.42mm without falling between the rails.

That forum post you've linked to provides some interesting reading. Presumably, your concluding recommendations are still valid for NMRA stock?

TG track gauge: 9.0mm MIN.

CG check gauge: 8.25mm MIN.

CS check span: 7.5mm MAX.

CF crossing flangeway gap 0.75mm MIN.

BB wheels back to back: 7.65mm MIN.

BEF wheels back to effective flange: 8.25mm MAX.

So I just need to work out something sloppier for MOROP?

I don't have any flat-bottom rail in stock, but I should get an order in for some and knock up a test turnout or two really.

Thanks for your help guys.

Alex

 

[Martin Wynne]

Presumably, your concluding recommendations are still valid for NMRA stock?

Hi Alex,

The latest NMRA specs are dated 2019, after I wrote the above. The tolerances have changed.

I think you could maybe tighten up a little for the latest NMRA wheel dims:

TG track gauge: 8.9mm MIN.

CG check gauge: 8.2mm MIN.

CS check span: 7.5mm MAX.

CF crossing flangeway gap 0.7mm MIN.

__________________________________

NMRA BB wheels back to back: 7.55mm MIN. (This is a bit tight on the check span and some wheels may need widening a fraction.)

NMRA BEF wheels back to flange: 8.20mm MAX.

___________________________________

For MOROP wheels to run on the above you may need to widen the back-to-backs quite a bit -- the spec allows a minimum of 7.4mm which clearly wont clear a 7.5mm check span. But you can't widen them too much because the MOROP flanges are thicker.

cheers,

Martin.