Tuesday, April 23, 2013

Scale & Gauge in Large Scale

Welcome to the wacky world of Large Scale were scale and gauge get confused. The problem is large scale uses a common track gauge of 45mm. The 45mm gauge is known as Gauge 1.  In Large Scale modeling a variety of scales and gauges exist on 45mm track ranging from 1/20.3 (3' narrow gauge on 45mm track) to 1/32 (4' 8 1/2" standard North American gauge on 45mm track). With all the scales operating on the same gauge track, it is easy to pick up your locomotive or cars, and take them to your fellow large scale layouts and successfully operate on them. Say your models are 1/20.3 and your buddy has a 1/32 layout, you both could run on each others layout without having to worry about track gauge problems. This could be compared to running On30 on an HO layout, or running HOn30 on a N scale layout. In the smaller scales this would never be acceptable, but for some odd reason it's okay in large scale. That brings me to my discussion of 1/29 scale on 45mm track.
For a variety of reasons, which I won't go into because it could take days, the scale of 1/29 exists on 45mm track. The track gauge is slightly too narrow to correctly model 4' 8 1/2" track.With 45mm track the correct scale/gauge combination is 45mm. I'm modeling in 1/29, but after spending a few years building my first layout I was never happy with the scale/gauge issue in 1/29. I kept hearing that it was not possible to regauge the 1/29 equipment to run on correctly scaled track. After some experimentation with USA Trains equipment I've discovered that it is possible to regauge 1/29 to the correct gauge without making major modifications. I haven't tried yet with other manufacturers so I'm not exactly sure.
Here's the numbers between 45mm gauge track and prototype track in 1/29 scale.

45mm= 1.7716"
56.5" in 1/29 = 1.94827"
45mm gauged wheel to the left, P:29 gauged on left.
A difference of ~.177"

A lot of people don't care about this difference, but to me it's noticeable.

Correctly gauged P:29 Track

Small section of hand layed track.
The point being that I'm going to attempt to build my layout to what I'm calling P:29 standards. The track gauge will be slightly wider than 45mm, but it will be the correct 4' 8 1/2" gauge for 1/29 scale. Throughout the process I'll be attempting to build as accurate as possible to the prototype track, this includes using large turnouts, and as big of a radius curve as I can. I'll also be using smaller code rail (code 215 or smaller) to better represent the lighter rail that was used on the branch line.
Yes I won't have the option to bring my locomotives, or have a visitor run their 45mm gauge locomotive on my layout but I can live with it. I wouldn't ask a HO modeler who models the 1930's steam era if I could run my modern locomotives during their operating session. So why expect/demand it in large scale?
#9 Turnout under construction


  1. Hopefully you'll find converting equipment to be easy. Nice turnout.

  2. Hopefully is the key! I'm attempting to regauge everything without major reworking so that in the future it would be possible to set back to gauge one standards.
    The key is finding out what works for the USA Trains equipment and going from there. Thankfully all my locomotives share the same gear box styles so one method works for all. Freight trucks don't have to get widened as they come built with enough 'slop' to enable a wider axle spacing without having to widen the truck spacing. Once I get a good system developed I'll post some more info and exactly what steps I took.