Alco C-855 R-T-R Build – Part 12 – Detail Parts

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.

Alco C-855 R-T-R Build – Part 11 – Lights

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 headlights.

These models are going to be DCC, but the same installation will work with DC as well.  The C-855 has a pair of headlights above the cab windows centered in the roof as you can see in the image below.   These lights are very small and although you can get surface mount LED of a similar size its hard to get them to look as rounded as this, or rather as the real thing.

To achieve this effect I have designed the two lamp holes to be printed into the 3D shell but the holes only go halfway into the roof.  For the other half I have designed a larger hole which can only be seen from inside the cab.  In the image below of the upside down shell you can see the larger hole above, or rather below, the windows.  This image was taken before I fitted the windows.

The hole is designed to accept a ‘2mm Lighthouse Warm White LED’ as shown below.  I use these for several reasons. They’re fairly cheep, the spindle part or lighthouse section is small but the rest of the LED is not too small to easily work with.  The warm white light is much closer to the original than the stark white of standard LEDs and the lighthouse design can be used to make a beam of light rather than just an all round glow.

It is important to note that LEDs unlike bulbs only work when the positive and negative wires are connected in the right way.  LED stands for Light Emitting Diode.  A diode, light emitting or not, only allows DC power to pass through it in one direction.  So if the wires are connected the wrong way around, it simply won’t light up.

There are three ways to tell which is the positive terminal on a lighthouse LED.  Firstly, you can see above that one metal leg is longer than the other.  This is the positive leg.  Secondly, looking inside the LED as shown in close up below you can see the split between the two internal parts.  The smaller of the two, shown at the top, is the positive side.

And thirdly, if you have your power source handy such as a 9V battery or 12v DC controller you can touch the LED contacts to the wires and it will light up when connected the right way round.  NOTE: a resistor must be used when doing this otherwise the LED will most likely burn out. This is because the LED will only be able to handle a low amount of amperage and with out a resistor to limit the current the LED, will draw all the amperage the power source has available.  The resistor can be on either the positive or negative side, as long as the power passes through it.  I will show you how I place mine shortly.

Because the LED omits light from all sides it’s important to ensure we only get light where we want it.  If you have one of the older Con Cor Gas Turbines, which chassis we are using for this build, you may remember that when the headlight is on, the whole cab illuminates.  What doesn’t help is the FUD or rather ‘Fine Detail Plastic’ material Shapeways use is porous to light.  However these shells have been primed and painted which gives a good block to the light showing through but just to make sure I always paint the inside of the cabs with a matt black.

I doesn’t have to be a pretty job, but I like it to be thick.  I also make sure I get some in the hole where the LED fits, this bit doesn’t want to be too thick otherwise the LED won’t fit.  I used to paint the LED with the exception of the top of the lighthouse to prevent unwanted light but I now have a better method  I will share with you in a minute.

The legs on the LED need to be cut down so the LED fits into the cab roof area.  Make sure you leave enough to solder wires to.  At this point the first way of identifying the positive side of the LED is no longer possible, unless you cut one longer than the other.

The LED wont go all the way into the hole because half way in the big hole becomes the two smaller headlight holes.

To stop the light filling the cab I now wrap the LED in heat shrink.  I use a tube which is roughly the same size as the box part of the LED and cut it so it will cover everything except the tip of the LED that goes into the hole.  If this part has heat shrink on it will not fit into the hole.

The box is actual bigger than it looks and the heat shrink tube is a tight fit but with some effort can be forced over the LED.

Then using my soldering iron I can shrink the tube around the LED.

The only part of the LED which can’t be covered like this is the rear of the box between the wires.  So I simply paint that with black matt paint.  A pair of tweezers are an easy way to hold the LED while painting as they naturally clamp it.

Once the paint is dry, 15 minutes with the acrylic paint I use, the LED can be test fitted.  Ideally the heat shrink should go all the way to the edge of the hole to prevent any light showing through.

For the resistor I have used a  small 1k ohm.  Being only a 4mm long it will be easy to fit into the space in the top of the chassis.  I cover the electrical connections to prevent them from touching the chassis with another piece of heat shrink.

I have soldered the white wire from the decoder to the resistor, the white wire is the front light negative.  The blue is the common positive.

The heat shrink is then pushed over the resistor, shrunk on with the soldering iron and it’s all tucked into the space in front of the decoder.

The wires can then be soldered to the LED.  Don’t forget to check which is the positive connection first.  I also used two small pieces of heat shrink to cover the joints.

With all the connections made and covered, I did quick test on the power to make sure everything worked.

Because the shell may need to be removed for maintenance at a latter date I don’t glue the LED into the cab roof.  I use a bit of black tack to hold it in place.  This should hold it firm but it can be peeled off at any point.  Black Tack is a high strength adhesive putty designed for photographers. I find it fantastic at holding decoders and other bits in place.

The head lights are now ready for the proper test and as you can see they look really good.

If your running on DC then you still need to use the resistor.  The wires coming from the LED, via the resistor, simply need to be connected to the chassis power points.  One to the left hand side and one to the right.  In the image below, taken from part 5 about fitting DCC decoders, you can see the two contact point which will also be used to connect the motor to.

Because the LED will only light up when power is applied in the correct direction the LED should only light up when the chassis is running forwards, on DC power.  If it lights up when running backwards the wires need to be reversed.

These models have not been designed with a rear headlight, mainly because I intended mine to run as an A-B-A set.  Therefore the C-855B has no lighting.

As this post turned out to be a bit longer than anticipated, I will leave the detail parts such as the fuel tank and etched details, for next week’s post.