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Would you model in 21mm if RTR track and models were readily available?

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Would you model in 21mm if RTR track and models were readily available?  

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  1. 1. Would you model in 21mm if RTR track and models were readily available?

    • Absolutely yes!
    • Maybe, if it was cost neutral?
    • No way!

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FWIW  I have asked Paul martin at Edm trains for a 21mm gauge back to back set - 19.3 mm to see what he can make - current guess was aruond £15 mark..  just now on Rm web asked Wayne Kinney about 21mm gauge point bases for code 75 BH rail.  His new and almost ready to go to market is based on a 3d printed flexible resin base with chairs printed - user has to put in rails but as in his N gauge models almost shake the box technology  and worth watching.   Using with C&L parts to make on plain track 21mm is much nearer.    Wayne could perhaps produce  trackbases in 21mm by same take and so the user just has to thread rail - an as long as not building all of Mayos lines or a scale length Belfast - Dublin line not three onerous .

two pics of N points from a few years ago


      before blades filed to shape 


The N version has a cast frog/ crossing nose for ease of building. It is sat on a natty paxolin jig for filing and cutting blades and joining on to a tiebar. The OO / 4mm version looks to have a moulded tiebar. 

Lets hope Wayne will be able to bring to market 21mm turnouts and perhaps more complex arrangements later. 


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Yes, definitely I'd buy 21mm track and points.  The sales opportunity lies in the new modellers joining.  One economical approach might be to create the sleepers for RTR track using 3-D printing, to allow an adjustable print-to-order.  The track could be sold as simple kits -- sleepers in strips with rails to be inserted.

Meanwhile, I bought Irish broad gauge sleepers from the ScaleFour Society and bullhead rail in code 75.  (Thanks, Jeremy Suter, for the help.)  Just need uninterrupted free time.  Working towards a combined MGWR Sligo line with Collooney Jct. to Dromod and the Cavan & Leitrim from Dromod to TBD.

A now-often-cited article about "the Long Tail" of a niche market might help explain how to think about models of Irish broad gauge (and Irish 3-foot RTR on 12 mm track).  You create the niche, in part, that people haven't articulated in masses -- you don't respond to an existing mass market.  The idea is used for a lot of niche-market sectors, such as a rare books library or historical museum that specializes in certain research subjects.  https://www.wired.com/2004/10/tail/


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I don’t think is a very good idea to be honest. Yes, while the broader gauge looks nice and is more prototypical. I can live without it as the negatives far outweigh the positives. 

It will add limitation to an established railway layout: i.e. not being able to run other stock. A lot of modellers don’t just run irish stock. I for example have a few UK locos that I like to run from time to time too. It is unlikely these will be convertible to 21mm if it became the new norm here.

Parallel to this, it will limit the appeal of Irish stock outside of the Irish market, which is already a very small market to begin with. When compared to UK and Europe. Limiting the interoperability of Irish railway models with existing track standards, will make our niche hobby even more niche than it is.


it just adds unnecessary cost to modelling without a lot of benefit. 


And finally. And possibly most importantly to anyone considering the monumental task of designing a new track system.... all the unforeseen challenges of designing points, turn outs, crossings etc... This is extremely risky / costly. This effort could be better invested elsewhere such as in developing more Irish locos, wagons, DMU’s etc...

Anyway, that’s my two cents worth. 

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IRM and to a lesser degree Murphy Models have already main streamed the possibility of modelling the Irish Broad Gauge using rtr locos and stock with IRMs range of bogie wagons and Murphy Models diesel locos all of which are simple to re-gauge. The IRM bogie wagons are convertible to Broad Gauge by simply moving out the existing NMRA 110 wheels on the axle or replacing with EM or S4 profile wheels.

Conversion of the MM B141 and 071 to broad gauge involves removing the existing wheels and drive gear from the axle and fitting to a 26mm plain axle which can be cut from a piece of 2mm silver steel rod or replacing the MM wheelsets if you work to EM or S4 standards. I re-wheeled two of my 141s with EM profile wheels as the wider stock MM wheels rubbed on the inside of the bogie frames when pushed out to 21mm gauge with a back to back of 19.3mm.

The question of whether there is enough demand for a rtr "21mm gauge" track system and rolling stock is an interesting one.

Peco developed a rtr EM gauge track system in conjunction with or for the EM Gauge Society and Sutton Locomotive Works produce a rtr Class 24 diesel that is available in OO, EM and P4 which indicates a possible "mainstreaming" of the 'finer scales". The EM and S4 Societies are both long established organisations with established standards and a considerable level of trade support including rtr flexible track systems, point kits and wheel & wheelset manufacturers.

21mm gauge is pretty much a minority interest within the Irish modelling community with possibly less than 20 people actively modelling in the gauge.

The majority of people who work in 21mm gauge tend to be modellers who enjoy the technical challenges of building (possibly offbeat)models as opposed to running trains (operating) or collecting models.  

21mm gauge layout is likely to occupy a larger space than an equivalent OO gauge layout because of the requirement for larger minimum radius curves than in OO, it would be difficult to build a large complex layout in a typical spare bedroom, single garage or attic found in the typical Irish or UK semi-detached house let alone a modern apartment or older terrace house.

Similar minimum radiuses to OO may be achievable by adapting similar track & wheel standards to OO, but would involve the compromise of reducing the gauge or increasing the width of some models to provide sufficient sideplay to run round curves.

A 21mm gauge model of a WT 2-6-4 or a D17 4-4-0 may be achievable if designed and built to S4 or EM standards but the gauge would have to be narrowed or the width increased in a model fitted with the wider NMRA 110 wheels.


Approx 0.5 mm clearance between driving wheel and inside face of splashers on 21mm gauge D17 built using EM profile wheels (2.4mm width) and 19.3mm back to back gauge. 

The splashers on this model were moved out to achieve sufficient running clearance, the gauge would have to be decreased or the width of the model considerably increased to compensate for increased wheel tyre width and increased component thickness in a plastic injection molded model.

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Interesting stuff, John, especially this quote: The majority of people who work in 21mm gauge tend to be modellers who enjoy the technical challenges of building (possibly offbeat)models as opposed to running trains (operating) or collecting models.  

I don’t actually do much operating myself, as I have discovered that I get far more satisfaction out of the research and  problem solving which building to 5’3” calls for. Tony Miles and Richard Chown had extensive 5’3” layouts ( a basement empire in the latter case), but also a fair amount of crew to call upon. I suspect for most of us, the choice is between a modestly sized scale gauge layout, and a large operating layout. I tried the latter in Japanese and didn’t actually enjoy it that much. Whereas a few hours with some sheet metal or plasticard and a scale drawing....





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I have to agree with Mayner on the volumes of active folk in 21mm and thoughts of issues with trying to provide more than modelling aids - if rtr provides the opportunity then that is the best that can be hoped for in the foresseable future.  An increase will be provided if trackage is reasonably easy to provide a working system - even if not every esoteric formation is made.   3D resin printing could indeed help with production but as  I have said before it makes it no cheaper just different.   

Long may the 21 mm band grow and continue to showcase all that is best for the hobby.        

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