Planning Calico: A Portable On18 Layout

The Calico Gold Company will be a 24" x 60" portable layout in On18 scale. Based loosely upon the Calico Mine Train at Knott's Berry Farm, the layout will also act as a feeder line connecting to the TMMC. Minimum radius on this plan is 10" and the ruling grade is 5%.

For a long time, I've been mulling over ideas for a small, portable layout or module that could be taken on the road to shows and modeling exhibitions as a representative sample of what Thunder Mesa is all about. I've also been toying with the idea of doing something in On18 that could act as a feeder line for the main railroad. And regular readers of this blog will know that I'm a huge fan of the Calico Mine Train at Knott's Berry Farm in California, having pretty much spent my youth there when I wasn't just down the road at Disneyland. Well, all of those ingredients have finally come together in a new 2' x 5' layout project that will showcase the style of Thunder Mesa while paying tribute to some of its Knott's/Calico inspirations.

A 1960's vintage postcard of the Calico Mine Train at Knott's. Just as the TMMC attempts to imagine a prototype for Big Thunder and Natures' Wonderland, the new Calico mini-layout will appear as something that could have, if it existed, inspired the attraction. The idea is for a model that shares visual cues with the Knott's attraction while not trying to be a slavish copy.

What the Heck is On18?

On18 is a funny scale/gauge combination that is intriguing to a dyed-in-the-wool rubber gauger like myself. It uses N gauge track and mechanisms as a starting point for 1/4" scale models in one of the slimmest of slim gauges. The 9mm gauge N scale track works out very close to 18" in 1:48, happily, a rather common track gauge for industrial and mining railways. The resulting models can have a lilliputian charm and character that really appeals to my sense of whimsy.

Concept illustration for a freelanced On18 locomotive inspired by the Knott's Calico Mine Train. This tiny drivered 0-6-0 will measure just 3" long in O scale and be powered by an N scale Atlas 2-6-0 mechanism. As a point of comparison, a diminutive Bachmann 0-4-0 Porter in On30 is a good inch (four scale feet) longer.

I've gone back and forth on the idea of an On18 feeder line several times; adding it and then removing it from subsequent track plans. Experience has taught me that if an idea keeps coming back around again and again, it's probably solid and eventually I'll have to do something with it. Well, the time has come and my long delayed plans for Calico will at last be moving forward with tiny trains on some very slim rails.

Refining the Concept

Designing the simple over-and-under figure eight track plan was the easy part. Figuring out where and how it will fit into the larger scheme of things on Thunder Mesa was the real challenge. Not only do I want the layout to be light and portable, I also want it to "plug-in" to the main layout as seamlessly as possible when not out on the road. It took some creative engineering and more than a few major tweaks to the TMMC plan to get all 10 lbs of both railroads to fit into the 5 lb sack of my art studio. I'll explain the changes to the TMMC plan in another post in the near future.

I still draw my plans the old fashioned way, with pencil and paper. I went through a lot of both figuring out where to place the Calico module within the larger scheme of the layout. There will be more on the updated overall plans for the TMMC in a future post.

Parts from Other Scales

Working in an oddball, niche scale like this means that just about everything needs to be scratch-built, kit-bashed, adapted or modified from materials, models or details in other scales. That's a big part of the fun as far as I'm concerned. Figuring out which bits and pieces from the smaller scales that can be useful is an interesting challenge. For example, I'll be using Peco HOn30 track and turnouts since the big, chunky ties and spike detail will look right at home in On18. Many carefully selected HO scale items can come in handy, especially things like locomotive detail parts and freight car frames. 18" gauge trains are small, so the roughly half-sized HO parts should work fairly well. Of course, N scale wheals and mechanisms will be used to model rolling stock. The trick is to find donor mechanisms that run reliably and that can be modified into something somewhat believable. I've already begun tinkering with a smooth running Atlas N scale 2-6-0 mechanism, removing the pony truck and mocking up ideas for the frame and cab. This may form the basis for Calico's first locomotive as illustrated above.

The 1:48 scale mechanics aren't quite sure where to start, but some HOn30 track, N scale mechanisms, HO parts and O scale details all get thrown into the mix when modeling On18.

Scenery and Structures

Naturally, figures, scenery and structures will be built at 1:48 scale, though since most buildings will be "smaller than life" caricatures, they will need to be scratch-built as well. Some structures, like the Calico Mine Co. warehouse below, will be modeled directly after the originals at Knott's, while others will be designed to fit the available space.

Color elevation plan of the Calico Mine Co., drawn from photos of the loading area at Knott's Berry Farm.

The scenic highlight of the layout will be Calico Mountain with its distinctive rock spire and waterfalls. No attempt will be made to replicate the interior scenes from the attraction but the dramatic high trestles and mine tunnels will be there, along with a truncated version of Calico Ghost Town - now very much alive with lighting, animation and sound effects.

Another vintage postcard from Knott's showing the spectacular sandstone spires of Calico Mountain along with the loading platform for the Mine Train.

Lightweight Construction

Since the layout will be portable, I'll be building it as tough and light as possible, using mostly polystyrene foam and very little wood. I developed a method for "cookie-cutter" foam benchwork for an N scale layout built some years ago and I'll be reprising that technique again here. The technique uses polystyrene foam sheet cut and fit very much like dimensional lumber for benchwork that is strong, sturdy and mostly air. Sub-roadbed is then cut from foam, cookie-cutter style, and glued into place with foam risers for elevation. I'll go much more deeply into detail on this lightweight construction method in a future post.

The Calico Gold Company will be built almost entirely from polystyrene and urethane foams. The integrated backdrop will be stretched canvas. The goal is a finished layout that can be lifted off of the larger Thunder Mesa pike and then travel to shows. A simple, folding stand will be constructed for the layout to sit on when it is away from home.

For the backdrop I'm hoping to use stretched canvas on a light wooden frame, very similar to the way theatrical scenery flats are made. The backdrop will be integral to the layout, both as an extension of the scenery and as additional structural support. If all goes well, it should be much lighter and more flexible than Masonite and will also serve as proof-of-concept for the entire backdrop system on the larger Thunder Mesa layout.

Much More to Come

With a plan I'm finally happy with it's time to get modeling and move forward. I'm not sure how long building Calico will take me, but as it's integral to the overall scheme of Thunder Mesa, it will be worth the time and effort to get it well started. No doubt there will be side projects and distractions along the way, and there is still so much to be done on Thunder Mesa proper that I should be very busy well into the future. Thanks for checking in, amigos. January has already raced by with a load of fun projects and the rest of 2015 looks like it will be a humdinger. Adios for now!