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find all about fiNe-scale modelling
in a scale of 1 : 160

 

building railcars

a preliminary glimpse on how you can produce a railcar

railcar 4403 in blue livery

railcar 4403 in blue livery

Method

In the early 90's I did an attempt to built a railcar of the 604 series but this was never fully finished. This was done in brass, hand drawn and etched. Therefor the windows lacked accuracy and being all slightly different I never got around to glazing them. Thus having a rainy holiday day and looking for something to do I decided to produce something better with the current tools. Normally the start is finding correct information about the item to built, in this case a railcar of the 603 series in its 1955 livery. I could only locate a small dimensional sketch with the main dimensions of length and bogie, the originally used information about window positions and sizes is hidden until today. But a trip on a dry day to the preservation railway in Maldegem with ruler, sketch book and camera was very helpful in producing correct dimensions and it made a nice ride. Backdating this to the 1955 layout was done with help of photos from books and lots of information provided by very helpful Fremo members.
When you have the dimensions you can produce a drawing and from this you can produce the necessary files for production. The drawing was produced in Corel Draw and the producting method is cnc milling.

The cnc milling requires a dedicated drawing that takes account of the radius of the cutter to be used. This requires that a contour is made at exactly the right distance of the original line. This can be easily done in Corel because it has an effect called contour function (F9) which does exactly that. Either outside, inside or the center with a given contour step. Exactly for this function I still prefer Corel above other packages. With this function you can create milling patterns on the fly. For plain jobs like this it is ideal. The above drawing shows the resulting pattern for the two sides and fronts including doors and some partitions and a false roof. You can feed this to the milling software as HPGL plotter file and this will produce the wanted output. In this case an 0.8 mm cutter was used for the major production with some additional cutters of 0.1 and 0.3 for surface details. The depth of cut and/or cutter can be stored as colour information and you may use up to 10 different colours. These can all be individually cut, thus I normally use that also to indicate the cutting order from inside to outside. You should generally first cut the windows and than the contour for the sidewall. The basic cutting order is normally top down following the list of objects, thus sorting them in the right order is another option. Further I find it useful to document the list of the cutters and depths to use as you generally tend to forget this sort of thing very fast.

railcar drawing

drawing with correct dimensions on top, milling pattern of all parts below.

The blue lines give surface detail like door contour lines and those on the front as help for painting its 'moustache' of yellow warning colours.
This drawing also shows the alternative fronts for the various rebuilt and updates the railcars got. The version with 2 headlights in single dark green, double headlights with 3 original windows and the later version with 2 windows in the cab.

Put a sheet of material on the machine bed, mount the particular cutter and let it do its work. This item was cut from .25 mm sheet, maybe thin but strong enough. Additional drawings were produced for the frame to be cut from 1 mm double sided pcb and the windows from 0.4 mm clear Evergreen sheet.
More effort takes the curved roof. The small contour in the right hand lower corner was a construct for the double curved profile to be cut. This profile was imported into a 3D drawing program and extruded into a 3D object for the roof.

roof drawing

roof drawn in a 3D software with added bevels.

The same holds for the interior although this was produced with 3D printing in mind instead of milling.

interior in 3D

A sketch with simplified interior but with integrated passengers.

the short bogie drawing

milling pattern of the short bogie

Also one of the bogies was drawn up. Essentially this was started out as a plain 2D sketch in Corel that was extruded into a 3D pattern.

result

The resulting parts glued together together with part of interior at the front and just at the edge the old metal part to be replaced.

painted pilot

Pilot version with colours

This is the pilot painted and with the windows in place. The light green should be a bit subdued. The yellow lines meant lots of trouble, painting didn't look good, airbrushing doesn't give sufficient cover. This here shows painted sellotape over the earlier attempts, also the green on the front was redone by brush with a bit darker green. Cutting thin strips is no problem using an angular board. For better cover it is probably better to first airbrush a white base layer before the yellow top layer.

three of a kind

Three of a kind, essentially copy the process 3 times and stick the lot together. The pilot version on front, 3 copies and a version of the newer 605 railcar which differs in details around doors and roof.


copyright: Henk Oversloot
date: 28 aug 2014
update: 22 sep 2014