Slight Digression - an earlier chassis
Entry posted by 2mmMark
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I found a set of photos I took when building an 08 chassis a few years ago. These predate the 2mm Scale Association kit for the 08 shunter and the chassis is now sitting under an original Farish body, with all its inaccuracies. My aim was to see how a triple stage high reduction chassis might turn out. Quite well as it happens. This isn't a complete build sequence but hopefully 2mm people might find the photos informative.
The starting point was a set of 9mm loco wheels which had failed QC checks for having inaccurately drilled crankpin holes. As I was going to convert them to outside frames, this was of no issue and the price was right... ;-). The wheels were mounted in my lathe and the centres drilled to make the axles hollow, to accept a set of cranks made from pins and parts of the Association etch of replacement coupling rods.
The cranks were set in place by means of a simple spacer
Here's an assembled wheelset
A set of frames from 0.5mm nickel-silver were set out for axles & gears, cut out and spacers made. The frames were fitted with shear pins to line up on the spacers before being finally screwed into place.
There was a touch too much sideplay in the axles, so I soldered some thin shims in place to take this up. They were made from phosphor-bronze pickup strip.
One small but key detail is an end-bearing for the motor shaft. This keeps the worm firmly in mesh
These photos show the gear train. The middle step-down is very close to the centre axle muff but there's just enough clearance.
Once assembled, the chassis block looks a lot tidier
Here's a close up of the motor shaft bearing. It also helps locate the motor in position
And the other end is fixed by a bracket
So there's a few ideas for chassis construction. I'm not sure that the complication of the triple reduction was entirely justified but the loco does have an appropriate top speed. It's a reliable performer and is very controllable. However so is the end result from the 2mm Association kit and that has a reduction around 40:1, albeit with a coreless motor.
Mark
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8
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