Desktop 3D printers

[nkp_174]

I've been designing my parts using standardized reference material and road-specific documentation and photos.

Some stuff can simply be scaled up or down, other things can't. For example, the sprue size when packing 4 truck side frames, 2 truck bolsters, and 4 caps to attach them together required sprues. I made them the minimum size, which requires them to be adjusted for different materials or scales.

Scalability...

Making trucks isn't as simple as drawing up something which matches a prototype, it also requires scale specific considerations. You can't design a truck without deciding what axles the wheels will have...needle point, shoulder, or flush? How long will they be and what is the diameter of the axles. What clearance is required? If brake beams are included, you should also select a wheel diameter. How will the trucks be attached to the car is also a design consideration. Printing my On3 trucks in HOn3 has required numerous changes to the truck bolster, journal boxes, and the the sideframes were made integral to the sides (On3 trucks usually allow for the sideframes to rotate independently for equalization while HOn3 trucks are rigid).

Whether parts are solid or hollowed out is scale specific. So is the walls thickness for hollow parts (e.g. the thickness of a railroad car's sides). This is a material specific consideration, and so an On3 car sides would probably have the same actual thickness as its HOn3 brother, but the scale thickness would basically double.

My first HOn3 truck should arrive next week along with a revised version of the On3 trucks. I'm working on the corresponding boxcar with the intention of offering it in HOn3 as a printed car, and probably as a resin kit in On3. I'm not certain of all the design tweaks that this will entail, but I'm awaiting an experimental print which I hope will guide the design tweaks for the full boxcar in HOn3 and On3 (and later, hopefully, Nn3 and Sn3).