Aster Hobby T3 / 89 7462 Tender modification - Gauge 1 / 1:32

thingiverse

In 1995, Aster Hobby created an exquisite scale model of a German Preussian Railways (K.P.E.V.) T3 / Deutsche Reichsbahn 89 7462 locomotive, featuring gauge 1 (1:32) live steam. When upgrading this model with RC-control, I discovered two significant issues: Firstly, the burner slowly heats the dwindling stock of alcohol stored in the burner, which eventually leads to the ignition of alcohol vapors when running for an extended period. This causes damage to any electronic and/or plastic components installed in the cabin. Secondly, it's impossible to fit all RC-control components safely within the cramped cabin at a distance from the hot boiler and burner (battery, receiver, 3 servos: direction, regulator, blower). To prevent the alcohol stored in the burner reservoir from boiling over, I devised a solution by separating the alcohol supply from the burner. I created a tank and sump from brass based on these ideas and drawings. For RC-control, I adopted an approach similar to others by mounting the servos to the locomotive and placing the RC hardware in the first wagon behind the locomotive. This design was inspired by the Deutsche Reichsbahn's practice of fitting tenders to some locomotives to extend their operating range. I designed a tender to store the RC-stuff, rather than a utility car, capturing the essential features of these tenders while not striving for 100% accuracy. My design is based on a standard German tender with three axles and a 12m3 capacity. I adjusted it to accommodate my homemade alcohol tank and sump. Spoked LGB wheels are fitted in 3 mm bearings, and I used buffers from one of my previous designs. The front axle is split into two sections to provide space for the alcohol-sump. A roof extending over the tender was designed based on the original Aster Hobby design, concealing the externally mounted RC-control-arms from view. To mount the servos under the steps and buffers, some metal parts required machining. All additions and modifications are reversible except for this machining. Initially, I printed the roof in PETG, but it's not very stable due to heat buildup in the cabin. Printing this item in metal would be an ideal solution, as 3D printed metal parts' prices are mainly determined by material usage. I've included an STL-file using minimal metal (File: DAK-Shapeways.stl). A new set of STL-files was uploaded after realizing my initial design was based on a similar but larger 15m3 tender. This revised model accurately represents the 12m3 tender. Fitting the air-tank on top of the rear cabinets is optional.