Tag: On18

Adventures in On18

The Horse Thief & Never Mine Ry.

Plans for an On18 mining tram to feed the Thunder Mesa mainline have gone through several evolutions over the years. Most recently, I've settled on a simple point to point design that operates between Never Mine tunnel through Baxter's Butte, and some as-yet-to-be-built ore bins at Horse Thief Canyon. In between, the tram will serve the richest diggings in the territory; Big Thunder Mine and the camp of shacks and outbuildings that have sprung up around it. Earlier versions had the tram extending all the way to Calico, and even included a portable On18 module at Calico Mountain. This plan was scrapped, mostly due to esthetic reasons since I decided a long On18 trestle in front of the backdrop would detract from other scenic features there like Horse Thief Canyon and the balancing rocks beyond.

An On18 Primer

Simply stated, On18 is O scale trains running on N gauge track. The "N" in N gauge stands for 9mm, and that scales out to about 18" in 1/4" O scale. 18" was a common track gauge for mining trams in the American West so the result of this scale/gauge alchemy is On18. I'm sure that readers of this blog don't need reminding about the esoteric differences between scale and gauge, but just in case you do, there's a post on it here.

To make things just a little more complicated, On18 trackage on the Thunder Mesa layout is represented using Peco HOn30 flextrack and turnouts which are, of course, also 9mm gauge. HOn30 uses N gauge track and mechanisms to model 2' gauge or 30" prototypes in 1:87 scale - but that's a story for another day. Suffice to say that this Peco track also has the perfect look for a light On18 mining tram.

On18 uses parts and materials from N, HO, S, and O scales to represent 18" gauge equipment in 1:48. Vertical boiler engine #2, the Walter Knott uses a 3D printed shell from Shapeways atop an N scale Kato 11-103 mechanism. 


Earlier Track Plans

As mentioned above, fitting an On18 line into the world of Thunder Mesa has been an ongoing process. Several plans were created and then later set aside as the line as it currently exists evolved somewhat organically on its own. Here are a few of those On18 plans, all of which incorporate Calico in some form or another. Though none of these are presently being built, each could work on their own in some future project.

Building the Horse Thief & Never Mine

The point to point On18 HT&NM Ry runs on a level between 5 and 6 inches above the On30 tracks of the TMMC. It starts at some ore bins at Horse Thief Canyon before quickly ducking into a tunnel and emerging at Natural Arch Bridge where it crosses the TMMC mainline. From there it's on to Big Thunder Camp, which sits directly above Rainbow Caverns, and into Never Mine Tunnel which passes through the heart of Baxter's Butte. The line terminates at the combination dump trestle and loading dock above Saguaro Siding. The sharpest curve on the line is about a 12" radius and control is standard DC. In the future, point to point operations may be automated using photic detection and a Circuitron AR-2 unit.

Track and roadbed being laid through Big Thunder Camp and across Natural Arch Bridge. Midwest products HO scale cork roadbed and Peco HOn30 track were the products used.

Track was primed and painted with artists acrylics. The trestle above Saguaro Siding was originally built for On30 rails, but it works just fine for On18. The scratchbuilt jib crane is used to bring supplies up to the mines from the TMMC siding below.

Ground cover is Polyblend sanded grout, and the ballast is red dirt collected near Sedona, AZ. Plants, weeds and bushes come from Scenic Express and Woodland Scenics. Cacti are from Pegasus Scale Models. 

The miner's shack was scratchbuilt from wood and Illustration board and features flickering lantern lights.

At least two more locomotives will join the HT&NM Ry roster, a tiny Shay, and a Porter-like 0-6-0, both currently under construction. The 0-6-0 is mostly being built from scrapbox parts, but the Shay has a 3D printed shell  from Marsh Creek Miniatures and runs on a Kato 11-103 chassis.

What's Next

Most of the track for the On18 line has now been completed and the rest is details and structures. One of the main features will be the Big Thunder Mine complex. This will be a combination of kit-bashed and scratchbuilt structures sitting on a high ledge above Rainbow Caverns. A below ground view into the caverns will also reveal the main shaft of the mine and an animated lift beneath the headframe. At the Horse Thief Canyon end, ore bins and a short trestle need to be built for the transfer of ore to TMMC trains. Also, if I can find the room, there may be a small turntable and engine shops in Big Thunder Camp. 

Summing up, I was a little sad to let go of the whole Calico mini-layout idea, but part of the creative process is knowing when things just aren't going to work and making the proper adjustments. I haven' given up on Calico Mountain, far from it, it just won't be a part of the On18 layout. But there'll be much more on that in an upcoming post. 

As always, I'll do my best to answer any questions in the comments below - so ask away! Just keep in mind that the WordPress platform is a spam magnet so it may take a little while for me to weed through and get to an answer. Thanks for checking in, amigos. Adios for now!