This is regarding printing railcar shells and locomotive shells with FUD on Shapeways. I'm working on a variety of projects in N, Z, and T scales. So, yes, some really small stuff. I have purchased several Shapeways prints from others and am currently working on designs in Blender. My experience with others' prints has frequently resulted in frustration with how thin the walls are, resulting in the walls sometimes warping or being ridiculously fragile. I can now say I think 0.03" wall thickness is too thin for FUD. I've seen this thickness and its issues a few times. My questions are: Does anyone have experience with what thickness works well to minimize warping and breakage? Would it really increase the cost of the print much if you would, say, double the wall thickness from 0.03"? Why don't more people use thicker walls? I assume this is partly due to scaling down models from larger scales and the walls aren't properly dealt with.
Shapeways publishes minimum wall and wire thicknesses for all their materials. I think that's .024" for a supported wall in FUD. Sometimes it is difficult to keep parts from looking too thick and clunky even in HO so it becomes kind of an issue to strike a balance between strength and appearance. However, where there is not a conflict, I do not hesitate to use thicker walls and/or wires wherever possible. I would agree that .06" is a good thickness wherever possible. Now that you're starting do do your own design work, you can also add bracing in places where the walls need to be thin for appearance. Above all, have fun.
The Shapeways standards are to make sure the item prints, not necessarily that it doesn't warp. An object that is at the lower end of the range will most certainly warp, even if it appears green in the 3D Tools test window. Most of the time you can unwarp it with pressure and hot water: just like bending styrene. A 'minimum thickness' is going to be dependent on the size of an unsupported wall. The difference between N and T is pretty big, so a minimum for one does not equate to a minimum for another scale. Regarding cost, most of it has to do with the volume the print takes up (but of course the amount of material still matters). For example, making a part hollow doesn't lower the cost a ton because it still takes up space in the printer, and space (build volume) is money for Shapeways. The more they can fit in a printer, the more cost effective it is, so changing side thickness doesn't always double or halve the price. If you print as a flat kit, flattening warped parts is easier, but a one-piece shell is easier to work with since you don't have to design part interfaces. For HO scale, .06" is probably safe.
