Friday, February 20, 2015

Building an On18 Locomotive: Part I

Calico Gold Company #2, the Walter Knott, fresh from the paint shop and on its way to the CGC facilities for final outfitting. Building this little On18 mine locomotive is the subject of today's post.


Before I start building benchwork and laying track on my On18 Calico Gold Company layout, I wanted a relatively simple On18 locomotive to pull some trains with. After doing a little research, I decided on a vertical boiler design that starts with a 3D printed shell from Tebee Models at Shapeways.com, atop a smooth running and reliable Kato 11-103 drive unit. This is my first real build in On18 and my first time using 3D printed parts. Despite the learning curve, the little steamer is coming together quickly.

The two axel Kato 11-103 drive unit is 2.125" long by 0.6875" wide. I'm using my N scale Pagosa & Southern switching layout as a test track.

The 3D printed shell from Tebee Models is made from polyamide nylon, what Shapeways calls their "White, Strong and Flexible Plastic." It is white and strong, but comes unfinished with a rough, sandpaper like texture. It fits perfectly over the Kato mechanism.

My first modification to the shell was to add a new stack. I cut off the top of the cap-stack on the printed body and replaced it with a taller HO diamond stack and some plastic tubing from my scrap-box. Here the new stack has been painted with grey primer. It's a snug press-fit over the original stack.

I'm not planning on adding a decoder to this tiny model so I filled the hollow spaces of the boiler and water tank with about 1.5 oz of BBs for additional weight. I mixed up some 2-part epoxy resin and carefully poured it over the BBs to cement them in place. I wanted to do this before painting the shell so any spills could be more easily cleaned up or covered. I let the epoxy cure overnight before going on to the next step.


The next challenge was to smooth out the rough 3D printed surface and make it look more like metal. Conventional wisdom says this should be done with primer and repeated sanding but I was concerned that too much sanding would wear away the details. Acetone vapor smoothing has been recommended for 3D printed parts but that only works for ABS plastics and not for polyamide nylons. I found a technique online for using several coats of plastic primer to smooth the surface so I decided to give that a try.

First I cleaned the shell thoroughly with a wash of 70% isopropyl alcohol. Next, I took the model outside for painting using Krylon Satin Finish Plastic Primer. Several coats are necessary because the surface is so porous. A second heavy coat was applied 20 minutes after the first. Then a third coat was applied 30 minutes after that. A fourth coat was applied an hour later and a fifth coat about 5 hours later. After drying for 24 hours, the shell had taken on a smoother, cast iron appearance.

More or less satisfied with the smoother surface, I masked off the black areas an sprayed the tank and bunker with satin finish Hunt Club Green. This is the "official" green for all CGC equipment.

Diving back into the scrap-box I was able to find the shell of an old MDC HO Consolidation and cut the smoke-box out from the backhead with a razor-saw. Then I wrapped some 220 grit sandpaper around the barrel of a marker and sanded a curve into the back of the piece so it would snug up to the boiler. The next step was making a new throttle from a paperclip and drilling a #61 hole above the firebox to receive it. The paperclip/throttle was ACC'd into place and the assembly painted flat black.

While I still had the flat black paint out, I masked off the green water tank and bunker and gave everything else a coat of the flat black to dull it down.

Looking at some photos online of similar historic locomotives made me want to add some brass bands to the boiler. These were cut about 4 scale inches wide from very thin sheet brass. I taped them down at the ends and sprayed one side with 3M 45 All Purpose Adhesive. After letting this set up for several minutes to get tacky, the bands were then applied to the boiler like tape, with just a small drop of ACC to keep the ends from curling up.

With the brass bands in place, the firebox and throttle assembly were glued to the boiler with thick ACC.

After looking long and hard at the model, I came to the conclusion that the stack was too tall. As a fellow modeler pointed out (thanks AJ!), a mine loco working in low clearance tunnels would likely have a shorter stack. So I went back and cut a scale 12 inches from the height and I'm pleased with the less cartoony look. I was also curious to see how well decals would adhere to the "smoothed" 3D printed surface so I went ahead and applied Walter's numbers and nameplate. A couple drops of Micro-Sol really helped the decals snug down onto the surface.


At this point, the Walter Knott is starting to look less like a collection of parts and more like an elegant early steamer. There are still many details to add: steam pipes, gauges, a headlight, bells and whistles, and link and pin couplers among other things. I also need to decide on whether to add a cab or not. There is much more still to be done but it will have to wait until more parts arrive. That's going to wrap it up for this time. Thanks for checking in, amigos. Adios for now!

Wednesday, February 18, 2015

Caboose Hop in Dinosaur Gap

The Daily Mixed steams back toward Thunder Mesa with drover's caboose #90 in tow after dropping a tank car and some stock at the interchange in San Lorenzo. It seems like the mines around San Lorenzo have been shipping less and less ore these days. In fact, if it weren't for the local ranches and the mail contract, the Daily Mixed to San Lorenzo might as well be the weekly mixed.

Sunday, February 15, 2015

A Pair of Cabeese

Or Cabooses if you prefer. Today's post is all about painting, decaling, and weathering TMMC crummies #90 and #91.

#90 is a drover's caboose and sometimes takes the place of Combine #101, bringing up the rear of the Daily Mixed with passengers and mail. Freshly shopped caboose #91 often travels the branchline up to Big Thunder Camp.


Custom Decals

The Thunder Mesa Mining Company is a rather well-to-do little railroad that takes good care of their equipment. To reflect this, I've had some fancy gold decals printed by Cedarleaf Custom Decals. I supplied Stan Cedarleaf with camera-ready artwork and he printed up the water-slide decals on his ALPS printer. Stan also offers layout and design services for those who can't do their own.

A sheet of Thunder Mesa's custom gold water-slide decals.

I liked the Bachmann factory color scheme on the drover's caboose, so I applied the decals to it without further modifications. The red caboose started out as a Bachmann Colorado & Southern short caboose. I removed the original C&S decals with acetone, then disassembled, primed and repainted the caboose with a satin-finish spray enamel called Colonial Red.  A smooth satin or gloss finish is always best for applying decals.



Applying Decals

There's nothing revolutionary about my decaling techniques, more like "tried-and-true." Getting things properly aligned can be the hardest part so I usually mark locations for decals very lightly in pencil before beginning.  Some modelers prefer small scissors for cutting out decals, I usually use a sharp hobby knife. The trick is to cut as close to the edge of design as is practical, thereby eliminating as much of the decal film as you can.

I have all of the tools and materials ready before getting any decals wet. A dish of warm water with a couple drops of liquid detergent to improve flow, a soft brush, paper towels, tweezers, a hobby knife and decal setting solutions are a must. The Micro Set helps to stick the decal in place while the Micro Sol is used to soften the decal so it will snug down over details. Both are from Micro-Mark. 

I pick up small decals by poking them with a hobby knife. Then I dunk them in the warm water for no more than 4 seconds - just enough time to loosen them from the backing paper and activate the adhesive. Then they are laid on a paper towel to soak up the excess water.

After wetting the decal, a little Micro Set is brushed onto the area where it will go. The decal is then positioned and very carefully slid off from the backing paper and on to the model. Sorry I couldn't get a picture of that step but it's really as straightforward as it sounds.

If the decal is not exactly where I want it, it can be repositioned with a soft brush or even a finger. Care must be taken though not to tear or wrinkle the decal. Yes, I've destroyed more than a couple this way and that's why I always have extras printed on a sheet. Once the decal is in position, I dab on a little Micro Sol to soften it and help it snug into the details. If too much is applied, I dab around the edges with a dry paper towel.

It's important to proceed slowly and carefully and not get in a hurry. When doing multiple decals like this, I let each one set up for about an hour before proceeding to the next. Then I let the whole thing dry overnight before tackling the other side. Yes, it can take awhile, but that's why I usually try and decal several models at the same time. That way, I can be working on one car while the other car is drying.



Reassembly

After decaling, the caboose was reassembled with new clear acrylic glazing for the windows and repairs made to the interior lighting that had not worked in some time.



Watercolor Weathering

Both cabooses were weathered using colored chalks, dry-brushed acrylics and watercolor washes. I wanted the yellow caboose to look as if it hasn't seen the inside of a shop in awhile - a little dirty and faded but still well maintained. The roof is weathered with chalks while the car sides got watercolor washes.

Watercolor weathering works particularly well on scribed walls. I mixed up a dark, warm-grey wash with Burnt Sienna and Ultramarine and then applied it generously to the car sides, letting it run and fill the scribe lines between boards. Once it was dry, I went back with a wet brush and washed most of it off, also dabbing here and there with a paper towel. The end result was a grimy look in the corners and crevices, much like this type of equipment gets in the real world.

The watercolor washes can be brushed on and washed off again and again to achieve the desired amount of weathering. Individual boards can be picked out with a wet brush and scrubbed "clean" here and there for a varied look as I did here on caboose #90.

I wanted caboose #91 to look as if it was recently shopped so I kept the weathering more subtle. I don't usually bother, but the chalks and watercolors can be fixed in place with a light spray of Testor's Dullcoat.



Final Thoughts

Both cabooses still need marker lights, figures and other details but they are complete enough to call them done for now. A magazine photo-shoot with a looming deadline was the impetus for getting off my keister and getting them finished and I'm glad that I did. Questions and comments are welcome below. Here's a final shot of caboose #90 from that shoot that wont be used for the magazine. Adios for now, amigos!

Engine #6, on a caboose hop near Lone Rock. I wonder what could be happening on the tracks up ahead to cause the train to stop here?

Wednesday, February 11, 2015

Afternoon Shadows

The Navajo people call this country the Land of the Long Shadows. It's easy to see why. Come afternoon, the lowering sun sends canyon walls and towering spires into sharp relief. Shadows from the canyon fall across the face of Baxter's Butte and the abandoned diggings of the Never Mine. Lazy clouds drift by and crickets sing in the canyon bottoms even as the upper cliffs are still bathed in the warm light of day. This is the time when the last train from San Lorenzo will return, shifting cars at the mill siding as the long shadows fade into night.

Background added in Adobe Photoshop. All else as modeled.

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