This week I’m covering the next part of my step-by-step build of a set of N Scale A-B-A ready-to-run Alco C-855 locomotives, which are almost finished. You can find part one of the build here. This step is all about adding the last detail parts and putting it all together.
I will start with the fuel tank. This screws to the underside of the chassis with the same screw which held the original Con-Cor fuel tank for the U50/Gas Turbine.
The new 3D printed chassis section is designed to accept the fuel tank in one direction only; there is a lug at the front and a hole at the back which lines up with the screw hole in the tank.
However it won’t fit without a little modification to the trucks. The inner trucks have a bar and hook which the original fuel tank sat over. This stopped the trucks from swinging out too far when you picked up the locomotive. It had no effect on the running or tracking of the trucks.
But because the C-855 fuel tank is a different shape these hooks need to be cut off to allow it to fit properly. In the image below you can see I’ve only cut off the vertical part of the hook as the horizontal section can still run into the C-855 fuel tank. This will still help hold the truck place. However, the truck can now swing out. If you plan to leave the locomotive on a layout and not handle it much then this won’t be an issue but if you plan to regularly move the locomotive, for exhibiting at shows etc, the one option is to extend the horizontal section and I’ll show you this a bit later on.
The fuel tank simply fits on the metal motor chassis with the screw hole aligning with the hole in the plastic insert. The insert was the piece which was fitted in part 4 of the build about the chassis assembly.
The insert is not threaded. It could be threaded by using a thread cutting tool but as it’s plastic or rather acrylic and the screw is metal it will cut in with a little effort to get it started.
The fuel tank has two holes in the side which, when fitted, will align with two clips on the shell. This holds the shell onto the chassis. ( I used a spare shell for the test fit as the painted one had just had its decals added). To remove the shell simply spread the shell at the fuel tank and pull apart.
Earlier I spoke about lengthening the pegs on the trucks to stop them swinging out. This can be done with anything you have eg. a strip of plastic or metal. I used an off -cut from the etched fret border. The left or front truck didn’t need to be extended but the rear did. I simply superglued the brass to the existing peg.
With the fuel tank refitted the rear truck can no longer swing out.
Next we come to the crew. These are modeled sat at the controls and include a platform with a grab handle on the underside for easy installation.
The two crew parts are designed with the engineer being offset to the middle of the locomotive. The grab handle will be closest to the side of the shell.
Although I always spray my shells with a primer first, with these tiny details I simply paint them directly with paints using a small brush. These areas are so small I don’t feel the primer will make much of a difference. I tend to use Humbrol enamel paints as they are normally finer than acrylics and better for small details. I know there can be an issue with using these paints on the 3D printed surfaces as they have been known to stay sticky for weeks but again for such small areas it appears to be okay.
I prefer the blue as a uniform color for my crew, it looks like denim and gives a traditional feel to the locomotive.
Inside the cab on either side are two shelves. The crew parts will sit on top of these shelves. The rear one has a step on top and this is the locating point to ensure the crew are put in the right place.
Using a pair of tweezers and holding the crew part upside down I test fit them first. Sometimes if there’s some print residue on the shelf they can be a tight fit and the end of the crew platform part may need to be cut down ever so slightly. I do this with the modeling knife.
Once I’m happy they’ll fit I dab the two ends of the crew platform with superglue and stick them in place.
The crew will now be visible through the windows.
The next details are from the etched metal fret. To the right of the fret are two small grills. These are walkways used at the rear of the locomotive.
I cut them out using a sharp knife. In the close up below you can see two burrs on the left of the top walkway which will need to be trimmed so it’ll fit into the shell. The walkways are handed, ie. they’re mirrored versions of each other, and the cranked face goes against the locomotive shell.
As always I do a test fit. There are two notches for the walkway to drop into so the top is flush with the checker plate printed into the shell. After I’ve confirmed it fits I dab a spot of superglue on each end and place it back into the model.
It’s these small details like this that make the model come to life, but if I’d designed these to be a 3D printed part of the shell they would’ve been very chunky, if not solid.
The next detail from the fret is the long walkway which goes onto the roof over the center of the shell. Again I cut it out with a knife and tidied up any burrs.
This walkway has a reduced section on each end which is designed to fit into a slot in the roof detail just past the large roof grill. As the shell has been painted it is probable that this slot has some paint in it, as it does in the photo below, and will need to be carefully opened up with the knife. Take care that no shell material itself is cut away.
Test each end to see if the walkway slides in. Once it does I spot, using a toothpick, a little superglue onto the areas where the walkway is supported, mainly the four raised strips, and a little on each of the reduced sections on the ends. Then I fit the walkway. Once one end is in it’ll need to be slightly bent, or curved, to get the other end in. The walkway can be pushed down and it should stick to the four raised sections preventing the walkway from bowing back up where it was curved..
To the far right of the fret are two sunscreens for the cab. These have tabs attached which fit into holes 3D printed in the cab sides.
The holes, above the windows, are already sloping up at the right angle so all you need to do, after a test fit, is dab some superglue onto the tabs and push them into place.
Again this is another detail which greatly improves the model.
The sun shades are not handed so either will fit on any side.
When I first started making etched sunscreens for my models, such as the DT6-6-2000, they were details which simply stuck to the sides and this made them weak. Having the tabs running into the shell gives them lots of strength and helps prevent them being knocked off.
One of the smaller details is the rear hand railing. The C-855B has one at the front as well. This is a cranked section located in the middle of the fret.
It fits between the two lifting lugs at the rear (And at the front on the C-855B)
Believe it or not this is one of the most fiddly details to add! (I blame the designer). There is a tiny shelf on the inside of each lifting post to receive the handrail and it can be really tricky to get it in. Of course that might just be me!
The last detail is the horns. This is 3D printed and can be a bit delicate. I brush painted it with UP Harbor Mist Gray.
Located on the top of the shell is a hole to receive the peg in the underside of the horns. When designing these locomotives, reference photos of the roof were very hard to find and I was unsure if the C-855B had horns or not. So I’ve made allowances for them on the C-855B and leave it up to you to decide.
The last parts to add are the sand boxes and handrails which I’ve left till last as these are the most likely parts to be damaged when handling the model. I’ll cover installing all of those in next week’s post which should complete this build.