Märklin Dr12 (Hr12)
Dr12 (before 1977 Hr12) has Swiss
designed boggies and similar boggies are used in Swiss Ae 6/6
electric loco. Märklin has manufactured these locos e.g.
as numbers 3050, 3350.
The building starts with this second
hand Ae 6/6 loco, which I purchased in German Ebay web auction.
Ae 6/6 is shorter than Dr12, so the Ae 6/6 framework has to be
extended with 14mm. In the Finnish model train magazine Junat
, issues 1-4/84 , is instructions and drawings how to build Dr12
bodywork of brass sheet. I designed rhe model with a 3D-CAD (Pro/Engineer)
and machined the parts directly with a CNC- milling machine. I
skipped the blue prints, because I didn't needed them. Below are
picture of the modelled parts and if somebody wants to use the
3D-models the files are here
in IGES-format
The complex form steering cabin
parts are machined of DuPont Cibatool and the sidewalls are 1mm
aluminium sheet.
The parts are machined with a small
3-axis ISEL-milling
machine, which is good for small CAD-models. Suitable materials
are plastics, wood and soft metals (aluminium, brass). The machine
is controlled with PC.
As an extension of the framework
I used a rather big block of brass. The increased weight is improving
the driving performance. The block is glued with epoxy and secured
with screws.
The assembly starts with the cabin.The
headlight has room for a 3mm bulb. Remember to make grooves for
the bulb wires.
A jig helps to align the parts.
Parts are glued together with epoxy
glue.
The front part with buffers is
taken from the Ae 6/6 and fixed with glue.
The exhaust pipes and cooling fan
frame is installed on the roof. The grids on wall are made with
0.7mm and 0.5mm wire.
The cooling fan is installed and
suspension parts of the Ae6/6 are glued to lower edge of the walls
First layer of primer.
The loco has been painted with
the preliminary colors. The paints are Humbrol's glossy red nr
19 and cream nr 41.
Fuel tanks are installed.
The original large flat commutator
motor (LFCM) is modified with Märklin kit 60904. The original
motor can also be used, but the driving characteristics improve
dramatically with this high-efficiency propulsion motor and load
regulated decoder. If the original motor type is DCM (drum commutator
motor) the Märklin modification kit is 60901.
The other end of the retainer spring
have to be bent more open, because the new motor doesn't have
a slot for the spring.
The hand rails are made of 0.7mm
wire. The loco number on the front (2205) is made with 2,5mm white
dry transfer decals. The logo of Finnish railroads "VR"
and the brass loco numbers on both sides are printed with ink
jet printer to Bare-Metal
Foil Co.:n Clear Decal Film. A larger picture with better
resolution can be downloaded here.
The light bulbs are from Miniatronicsin diameter 2,4mm and the headlight
above cabin is Märklin's 3mm bulb.
The bulbs are glued with white
glue.
The electric schema is above. The
two lower lights in both ends are connected to function F2. A
resistor has be added to the Miniatronics' 16V bulbs. The resistor
value in this case is 150ohms.
A connector between the bulbs and
decoder is useful.
Test run on the turntable.
Next phase is to add windows, horns,
bell and stairs.
and the story goes on as the project
proceeds....
