Tuesday, 16 April 2013

Designing the K Class (1932) for 3D Printing in 1:120 (NZ120) Scale

Currently I'm designing the K/KA/KB class for nz120, a version of the K with ACFI feedwater equipment is also being talked of so who knows what will eventuate!
History
The three G class locomotives were introduced by the New Zealand Railways Department (NZR) in response to increased tonnages, especially on the mountainous, demanding North Island Main Trunk Railway. However, various faults led to their swift withdrawal from service and NZR still needed a large and powerful type of locomotive. It decided to develop a conventional rather than articulated locomotive, to avoid a repeat of the G class failure.
Initially conceived as a 4-8-2 locomotive, the K class was to be at least 50% more powerful than the AB class, and due to New Zealand's narrow gauge track and limited loading gauge, the power had to be very carefully compressed into an area smaller than would usually be used for such a locomotive.
Constructed at Hutt Workshops, the class utilised plate frames, partial mechanical lubrication, Franklin butterfly firehole doors, and roller bearings on all but the trailing bogie. The class had a distinctive appearance when first outshopped, with a pressed smokebox front and the headlight jutting out forward of the top of the smokebox. This latter feature was soon changed at the insistence of one of the Railway’s Board of Management – instead it was sunken flush into the smokebox, which required some modification and changed the aesthetic look of the class quite markedly.
K 919 was given an ACFI feedwater heater system as a trial, a feature that was continued on the subsequent KA and KBclasses.

Sourced from Wikipedia
The design of the K at test stage. An order placed for the K including the tender & bogies. This will help in the final design, thus is the advantage of rapid prototyping. The rivets placed along the tender sides and rear are perfectly prototypical. I'm pretty sure it will please even the "rivet counters"!


Some pictures of progress & prototype


 




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