Large Scale Central

O Guage min diameter curve

The dreaded minimum dia/rad curve question.

So I am beginning to think that next year I might start the expansion of the CR&N with the Fn2/O gauge run to another part of my yard. I want to run 32mm track for two reasons. I like the idea of a Fn2/fn3 dual gauge interchange. I also have acquired a couple of Steve Feather Kyle’s O collection that I would like to convert RC/battery and run on a dog bone. Steve’s O trains are the main driving force for the 32mm track. But the buildings and everything else will be set up as 1:20.3 (1:24) to match the existing layout.

With that said The locos I acquired from Steve’s wife are a FA and FB and then some passenger cars which are not extraordinarily long. I am not concerned with what “looks” right as far as overhang for the O gauge. I am more concerned with what it will reliably handle. I am seeing both 60" and 72" diameters coming up online. Is this fair? Can i really do 60" and get away with it because that would be awesome. I know many of the “toy” trains and Lionel starter sets came with much smaller diameter curves. So I am really hoping I can get away with 60" diameter. I think that would be plenty small enough.


Most Lionel starter sets come with 36 inch DIAMETER track (18 inch radius). The Madison cars for the Polar Express do not look too bad running on those curves, so I would say that 60 inch diameter would work, especially as narrow gauge track. The narrow gauge usually had tighter turns and clearances than standard gauge.

Will you be using two or three rail track? GarGraves make both kinds, I think. If the track is going outdoors, the wood ties will need some kind of preservative treatment upon installation, then perhaps every other year after that - depends on your climate.

Best wishes, David Meashey


The narrow gauge Fn2 I am not at all worried about. It will be all very small equipment like a mining tram and maybe some backshop type box cars. The main issue will be the standard O gauge stuff I have from Steve. But I know what the polar express cars are like and the ones I have are not any larger. And i am not worried as much about their “looks” on the rail as I am their ability to make the curves. And You pretty well confirmed what I thought that 60" should be more than adequate.

As to track I will most likely use Atlas 3 rail. Couple reasons. One I already have several turnouts for it. and Two I am not yet committed tot he RC battery for the O. I may keep it DC and tun 3 rail. The atlas 3 rail is supposed to be UV safe plastic. So it should work outdoors. And since the most expensive part of this adventure would be turnouts I am way ahead of the game in that I have all I will need. So that pretty well has made the decision for me.


Just an aside regarding Atlas. They have purchased a fair amount of MTH tooling for passenger cars, freight cars, and diesels (no steam, though). Some of that selection may interest you as well.

Best, David Meashey