The superstructure of the wagon is mainly made of wood. To be able to store the wagon, it's made removable from the frame. The wagon supersturcture, alias 'toolbox on wheels', is fixed with 8 M4 bolts that connects the cross-members to the floor.
Essentially a wooden box on wheels 😀. The 9 mm plywood cut to size at our local DIY store.
In Solidworks it didn't look that big.
Special insert nuts are used. In a wooden strip these 8 nuts line up with the under carriage.
The wooden strips, with the insert nuts, glued and screwed to the floor plate. It is held in position with notches that 'grip' the horn plates on the frame. The bolts ties it down.
The sides of the wagon are cut to size.
The radius of the roof is CNC milled to size.
The same method for making the grooves as used when making the Omk wagon. This way the individual planks are resembled. These planks however are much smaller then on the Omk open wagon.
This refrigerator van (Kühlwagen) has a smooth outside cladding.
The steel frame (on the original wagon) was sandwiched between the outer cladding and the inside wall.
Because of the smaller planks, it takes up more time to cut all the grooves.
The first assembly. The side walls are only glued to the floor. Because the side walls extend under the floor, a 3 mm rebate was cut; too small for using screws.
A cross sectional view, showing the construction.
A first view of the wagon. The H0 Märklin wagon is standing in the door opening.
A test drive at the track of the SMMB in Tilburg.
For the roof, curved roofbeams are milled. A strip of 10 mm aluminium is used as a fixture. With four bolts the wood is clamped and can be milled on the full circumference in one operation.
A 4 mm soft plywood plate is used as the base of the roof. This material can be bend without to much difficulty.
In one batch I could glue 5 roofbeams in a row; then all my clamps were at use.
A steel tube is used as a "building keel" to keep it reasonable straight during gluing.
The first longitudinal member is put in.
On top of (or rather on the bottom, once the roof is on the wagon) the longitudinal members, crossbeams are glued. These a pine strips that have their fibres in the length of the strip; and therefore are able to take up the tensile strength caused by the weight of a passenger sitting on the roof.
I've tested one crossbeam and it was able to take a weight of 40 kilograms, before any deflection was noted.
It looks a bit like ship building. I've once build a model boat, were this technique is used.
A meranti strip, on which the roof will rest.
To create more thickness and to model the double roof, a 3 mm hardboard is added.
This is cut in parts of 150 mm wide. To glue such a large plate in one operation would be difficult and now it resembles the separate bands of roofing, as used on the original wagon.
Some weight is needed to press it down during gluing.
The roof taking shape
The roof will be hinged. Other model engineers told me that this is the best way to avoid damage to the roof. If it was detachable, it would put against a wall, or put on the floor and this way the corners would get damaged more quickly.