How would I do these smol NS electrics in N?

[Jim Starbuck]

Width at the sill  18.33mm
Length at the sill  69.74mm
Width of the cab. 16.48mm
Cab front to rear. 18.11
Sill to cab eaves 14.42mm
Bottom of sill to top of cab 20.28mm
Sill thickness 2.84mm
Cab roof front to rear at overhang 20.59mm
Cab roof width at overhang 18.13

[Iain]

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Had a go at getting the basic model done.  I'll wait for detailing further until there's a viable drive.


Here's the .stl; let me know if there's any changes you need.

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[Jim Starbuck]

Excellent!
I’ll get this on the printer and start working up my drive concept.

[Jim Starbuck]

The shell printed nicely so with a fixed target I started to build the mechanism. The trucks are the geared ends of two Kato 11-105 powered chassis. The bolsters were cut from the donor chassis and inset into .040 styrene which had been fit to the shell. I milled space in the styrene for repurposed pickup strips from the Kato chassis. The brass tabs on the trucks were filed shorter to allow the new chassis to sit all the way down. Hopefully this works well but if not the trucks can be hardwired.
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The rotating assembly is a 7x16 dual shaft motor held in printed mounts which were drawn in Fusion 360. The homemade flywheels double as shaft adapters as the motor shaft is 1mm and the worms run on 1.5mm. He worms are m3 3x5mm replacing the stock 4mm Katos and keep the profile as low as possible.
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There’s more material to add to the underside and also air tank detail that will mitigate the giraffe riding a bicycle ride height look.
So far so good as it all fits under the hoods.
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[Chris333]

Jim, Don't know if it is just the photos, but the worms look like they need to be pushed out more to be centered over the truck gears. The way it looks you might pick the edge of a tooth. But I'm sure you'll get it figured out in the end.

[Jim Starbuck]

Good eye Chris. Thank you.
In the photos the motor assembly is just sitting on the chassis. I still need to file the ears on the mounts to lower the motor and establish gear mesh with the trucks. I admittedly crowded the worms inboard and may have move them out a bit in final setup.

[Iain]

Could you get me a drawing of the flat bit of the frame with critical dimensions?