Body Preparation and Details
Take care when removing the support structure from the body, especially around the cab windows to avoid damaging the vertical dividers between the windows.
Once the body has been "cleaned up", it is also necessary to remove the two temporary braces which link the fixing posts near the centre of the body, as highlighted in yellow below. These have been included to protect the body during production and shipping, and must be cut away to provide clearance for the motor, etc. These can be cut with a fine-toothed razor saw or a cutting disk in a rotary tool, as low speed.
The eight fixing holes in the body shell should be tapped with a 2-56 thread. If necessary, clean out the holes prior to tapping using a 1.8 mm drill bit.
If using dual drive bogies, there are areas marked on the lower, end wall of the cab which need to be cut out to provide clearance for the front drive shaft and bogie mechanism. These are highlighted in yellow in the image below.
Handrails
Starter holes are provided on the body for three handrails which can be formed from brass wire (e.g. 0.3 or 0.4 mm). The started holes should be drilled out slightly larger, e.g 0.05 mm larger than the wire size.
One handrail is inside the recessed step nearest the top on the left side of the loco, next to the radiator grilles. The spacing between the holes is 3.5 mm (centre-to-centre).
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| Photo by G Stallard |
The other two handrails are on the roof, adjacent to the recessed steps. The spacing between the holes is 8 mm. Photos indicated that the bends in the top handrails should have a radius of approx. 1.5 mm. Radiussed corners can be formed by bending the wire around the shank of a drill bit, or using special pliers with round jaws.
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| Photo by G Stallard |
Starter holes are also provided on the end walls of the cab for the long handrails which run along the side of the loco - see below.
Long Handrails on Underframe
The 3D-printed chassis incorporates holes approx. 0.6 mm diameter to house the vertical handrail posts, typically cut from 0.6 mm brass wire.
One option for the handrails is to solder each section of handrails from 0.6 mm brass wire. Marbelup Models can supply a PDF template for the handrails on request or download it from D/DA Handrail Template. If printing the template yourself, make sure you print at 100% scaling to get the correct size.
Note that the end walls of the cab have starter holes for the horizontal handrails. Assuming 0.6 mm wire is used for the long handrails (and shorter ones at the front of the loco), it is suggested to drill the holes in the cab end walls slightly larger e.g. 0.7 mm, so the handrails are an easy fit. Ideally, the handrails should be trimmed so that just enough extends into the holes (e.g. 0.5 mm) so they they appear to be attached when the loco is fully assembled. If the handrails extend too far into the holes in the can, it will be more difficult to disassembly the loco.
Use of A-Line Handrail Stanchions
An alternative, which is potentially easier than soldering, is to use preformed steel handrail stanchions available from A-Line (Division of Proto-Power West, USA). These are available from various online hobby shops and/or eBay. (Marbelup Models has limited stocks of these stanchions available at $15 per pack of 35 stanchions.)
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| A-Line Handrail Stanchions |
Although these stanchions are intended for HO locos, the two longest sizes are sufficiently long to be trimmed to the correct length for the D and A. The A-line part numbers are D1071 (long) and D1071 (extra long). The stanchions should be trimmed at the bottom to a length of 18.5 mm, measured from the top of the "loop". For the handrails on the end platform, the stanchions should be trimmed to 17.5 mm. After trimming, file off any rough edges from the cut end.
The holes in the 3D-printed chassis should be carefully drilled out to accommodate the stanchions (suggested drill size: 0.75 mm - test on some scrap plastic first). Carefully insert each stanchion vertically into the drilled hole, taking care to align the loop perpendicular to the sides of the loco. It is also suggested to orient all stanchions the same way, e.g. with the open side of the top loop inwards. Make sure the bottom of each stanchion is level with the underside of the running boards.
Once the stanchions are installed, 0.6 mm brass wire can be threaded through the line of stanchions to complete the handrail. Some custom bending will be required at the ends of the loco and where the height of the handrail varies. The PDF template may be useful for this.
Once all the stanchions are in place and the long handrails threaded through, check that all the stanchions are vertical and make any necessary adjustments. Then, the brass handrail can be secured to each stanchion with superglue and, if desired, the stanchions glued into the holes in the running boards. Note that the short handrails in front of the cab should not be glued as they may need to be removed prior to separating the body and chassis, e.g. for maintenance.
Horns
Four horns are included as part of the 3D-printed underframe. Carefully remove them from the underframe, leaving the spigots attached to the horns intact as much as possible. Only two are required, with two spares.
(Alternate horns can be source from detail parts suppliers e.g. in brass, if greater robustness is desired.)
Starter holes are provided for the horns on the rear wall of the cab (right side) and on the front wall of the cab (both sides). Early photos show the front horn on the right side of the loco (as pictured below) and later photos show the front horn on the left side of the loco. Consult photos appropriate to the era being modelled to determine correct horn placement.
Drill out the starter holes to suit the diameter of the spigot on the back end of the horns. Carefully trim the unwanted spigot projecting sideways from the horn.
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| Photo courtesy of Rail Heritage WA. |
Headlights
The holes provided in the body shell for headlights are nominally 1.8 mm diameter, but typically slightly undersize due to the 3D printing process. The headlights should be 2 mm in diameter, so drill the holes out to 2 mm taking care not damage the thin surround around the hole.
(The holes are deliberately undersize because the thin surround would not print otherwise, as the minimum detail thickness is 0.5 mm. and the outside diameter of the surround is 2.8 mm.)
One method of lighting the headlights is to use a short length of optic fibre together with a 3 mm LED (Light Emitting Diode).
The D and DA locos had "sealed beam" headlights for which "sunny white" LEDs are a suitable approximation. (Many older locos had larger diameter headlights with replaceable bulbs which tended to have a more yellow appearance, similar to "golden yellow" LEDs.)
Note: Incandescent (filament) lamps are not recommended due to their high operating temperature which may damage the 3D print material.
To attach the LED to the optic fibre, 3 mm black heatshink tubing is recommended. With the use of a hot air gun, the heatshrink tubing will shrink to form a snug fit over the optic fibre. However, the hot air may well be hot enough to melt the plastic optic fibre, so the trick is to shrink the tubing over the shank of a 2 mm drill bit, them slide the drill bit out and slide in the optic fibre.
Typical steps are:
- Cut heatshrink tubing to length, e.g. 8-10 mm.
- Hold 3 mm LED in a small vice by its legs, with the clear lens uppermost.
- Push the cut length of heatshrink tubing over the clear lens of the LED.
- Hold the shank of a 2 mm drill bit inside the heatshrink tubing while applying heat from a hot air gun.
- When it has cooled, withdraw the drill bit and insert the desired length of optic fibre. For the rear of the loco, you will probably have to feed the non-flared end of the optic fibre through the curved hole provided (from the outside) and attached the LED with attached heatshrink tubing on the inside.
CAUTION: Do not used the hot air gun or other heat source to shrink the heatshrink tubing in close proximity to the loco body or other 3D printed parts as they may distort due to the heat.
For the dual headlights, it is simplest to wire the two LED in series as this reduces the wiring and avoids the need for two separate resistors. A resistor of around 2K2 (2,200 ohms) is a suggested starting point for LEDs powered from DCC decoders.
A "conduit" has been provided in the roof of the cab to allow the headlight wires to be fed through into the short hood.
Marker lights can also be drilled out and illuminated if desired.
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