< Start of New Project>
My second project has different concept from the first, in both its volume
and construction method. Therefore it took much time to resume this report.
The prototype is Japanese C53 type heavy pacific locomotive with three cylinders. To return the project, it will be 1/8.4 scale model on 5 inch track gauge. It means the locomotive volume is 5 to 8 times bigger than the first project 'William'. As long as I obey elaborate scratch building, the second model won't be completed in 10 years. So I changed the concept as follows. In order to minimize machining work, I will make full use of precise castings and laser-cut (and bent, if necessary) sheets. Also I adopt 3D profiler 'Modela' so as to make wood patterns for the castings. And boiler construction will be ordered to a professional.
The picture shows chassis construction that I have designed until now. You can find equalizing system and brake system in the picture. It is an output of 3D-CAD which I employed for designing, instead of 2D-CAD. Fortunately I obtained complete drawings of the prototype. Striking parts are truly reproduced from the drawings, while hidden parts are drastically simplified.
The photo shows Modela MDX-20 made by Roland DG. It is a personal use 3D miller and scanner. Practically this cannot cut metal, but finely cut wood, wax or soft resin. You just prepare 3D-CAD data, mount a wood blank and click 'start', then the machine will complete wood pattern that you want. This is a dream machine? However you need considerable time to prepare 3D data for a cutting.
The machine itself is noisy but is in a soundproofing box (option) which allows the machine to run in the night. If you use hard wood, it takes much time to cut. If you use soft wood, it leaves rough surface. I think the most suitable material for wood pattern by the machine is soft chemical wood, although it is a little expensive.
Maximum handling size is limited due to the machine case. For example, driving wheel pattern for C53 (220mm dia.)was cut into quarter size, then glued together.
Completed driving and coupling wheel patterns.
Leading and trailing wheel pattern under cutting in the Modela. The blank is mounted on the base plate with both-side adhesive tape, which is enough for such a light cutting.
It takes more than ten hours to cut a large and complicated pattern. During the operation, the tool spindle keeps rolling. Motor and spindle units have to be replaced in every 700 hours. In my calculation, the running cost is about a half of the material (chemical wood) cost. Of course it is far cheaper than order made patterns. However it is comparatively expensive if you are used to handmade patterns from wood scraps.
Recently it is not easy to find out apposite foundry who accepts small personal request. In my case, a foundry company's engineer who had seen my web site offered to help me.
Finished wheel castings. They are made of ductile cast iron (FCD) that has higher strength than typical cast iron.
I ordered laser cut chassis (12mmt for the front & 6mmt for the back). The material is bright mild steel. For the back chassis, I requested bending work because I have no strength to bend 6mmt steel plate! Also I ordered other parts of 12mmt and 6mmt at the same time.
Don't order a pair of chassis with one drawing. Draw two chassis in handed pair and order one by one. Laser cutting always has risk of warp. But if it is in opposite direction, it will be canceled with assembly.
With my son, I have been to Kyoto Umekoji steam shed in where one and only left C53 is preserved. I took 200 photographs with my digital camera to record locomotive details.