Creating a model TurnTable and various model trainsA wellknown application of scale models is the world of model railroads. A number of large manufacturers offer scale model trains as a mass product, of course only of the most known train types. So there is also room for suppliers of specialty models in small series.
One of these suppliers of specialty models is EpokeModeller in Denmark. The models are produced using various techniques, all based on a CAD model. The CAD software used is Solid Edge, the CAM software (of course) is DeskProto and the milling machine is an Autograv (no longer available).
Left the original turntable, and right the CAD model of the table in Solid Edge.
EpokeModeller not only creates train models, but also related models like the turntable shown here. A turntable is a piece of a rail track that can rotate. A train can run onto the table and stop. Next the table rotates, and the train can run further onto a different track. The original of this model turntable was built as a standard for several stations on the Roskilde-Korsor railroad (Sealand, Denmark) around 1850-60's. It is a 42" (12,8 m) bridge turning on a center bearing. The turntable is named the "Kongestols drejeskive", a beautiful name that can be translated as 'Kings chair rotating disk'.
The rotating part of the table is called the bridge, it rotates over a ring shaped rail. This ring rail is placed in a concrete foundation (a circular hole called the pit). It serves only to support the bridge when it is unbalanced, for instance when the engine runs on and off. A few of these turntables are still in active service, but most have been replaced by 20 m turntables.
Left detailing the beam in DeskProto, right machining on an Autograv IV.
The model is on scale 1:87, which is the standard railroad scale H0, with manual turning. Still the construction makes it possible to add a simple mechanism for automatic turning. The model comes as a kit, so it has to be assembled by the customer.
The complete turntable model has been designed in Solid Edge, as one large assembly containing all separate parts.
Left the bridge being assembled, and right the resulting assembly.
The pit's main shape has been created by turning from a solid block, after which the details have been 'added' by CNC milling. The rail in the pit is glued into a groove which was milled in the surface of the pit.
The bridge that rotates inside the pit consists of a number of separate parts: the central bearing that consists of a metal axis in a block of tooling board. Onto this block two beams are attached, and on top of the beams rests the wooden floor. EpokeModeller have applied many techniques to create these parts.
Left the etched parts in metal, and a detail right: the lock.
Both the bearing block and the 'steel beams' have been created using DeskProto. The actual beams have been cast in polyurethane resin, using a silicone rubber mould that was made round the machined master model.
The wooden floor is created from on thin sheet of wood, by laser cutting from a 2D drawing.
Finally all metal parts (the railings, the lock etc) have been created by photo-etching sheet metal, also based on 2D drawing information. The 2D drawings used were DXF files from Solid Edge.
The resulting turntable model.
As said above, EpokeModeller also offers train models. Their preferred period is Danish trains from 1880 to 1920. See the two example models below: first the passenger car type AA of the Danish railroads, used between 1893 and ca 1952, and next a locomotive called called DSB MY.
1:87 model of the Danish type AA passenger car. Click on each picture for more.
The AA model has been created by assembling separately created walls, floor and roof. Each of these has been manufactured using two-sided machining in tooling board. Scale of the model is HO (1:87).
1:220 model of the Danish DSB MY locomotive. All model were made using DeskProto.
The MY model has been created as a solid block, machined from five sides by turning the part on the machine as well as in DeskProto (this resembles the technique described on Gallery page 5-axis). This model then has been used as a master for rubbermoulding. The locomotive is scale Z (1:220), so it is only 76 mm long ! Even on this small scale details like the ventilator and ventilation grids are present. The model has been finished by Mikkel Sen in Switzerland.
From the EpokeModeller website you can download their catalogue with train models and model parts, as PDF file.