Tips for making a nested design ready for 3D printing.

Hi,

I'd like to know how I should ready a specific design for 3D printing.

To be more specific, the design is composed of a very large number of arcs and blocks which are all nested together to create a large square, which in turn is used in a set of six to compose a cube.

I have no experience readying a model like this for printing (have no experience with 3D printing in general, but normally when I model I usually create single piece models rather than multi-piece models like this).

My main concern is that since the model is made of hundreds of individual sub-pieces, what do I need to do in order to ensure that all of the pieces are properly connected for printing?

Can I just place the sub-pieces flush against each other and will the printing software interpret all perfectly adjacent and flush pieces as contiguous and therefore sufficiently connected, or do I need to explicitly attach the pieces to each other within 3ds Max?

Also if the pieces are connecting to each other at different angles (so they're not flying flat upon each other or side-by-side) is that a problem or is it okay if there is sufficient amount of surface connection/overlap, and if so, what constitutes sufficient connection/overlap?

Thanks in advance for the help!

I'm pretty sure the upload software has a mesh repair component that will connect overlapping objects. It's worked for me when the software I was using was unable to do this grouping on my desktop computer for whatever reasons. I'm not sure if it works as well for objects that are adjacent/flush to each other without overlap. You can experiment with an upload and look at the model details that will give you some numerics on how many pieces the Shapeways computer thinks are in your file.

As far as connection/overlap area goes you need to look at the material design rules for minimum wire and wall sizes for the connections. But you also can't connect two HUGE objects with a minimal sized wire, for example, because the connection joint will probably break during cleaning and handling.

I take it that you want this square to be a single not-decomposable piece, something like a decorative tile and not a construction kit or puzzle ? Then adjacency of parts should in theory be sufficient, but in order to avoid possible problems due to numerical (rounding) errors it is probably advisable to
have them overlap slightly, or do a "boolean join" of all the subparts in your modeling software.
Do you want the model to be colored like in your images right out of the printer ? Currently the only material on offer here that supports multicolor printing is
the "full color sandstone", which is basically gypsum powder held together by colored glue. The process has the disadvantage that the model is initally very brittle and has to be transferred to a glue bath to gain stability. The associated handling problems put a limit to the level and nature of detail and call for relatively thick walls. What is the intended size of your model ?

Thanks-

I'll probably just go ahead and slightly overlap pieces...although that will probably increase the difficulty of completing the print ready model, because that's going to shift things around, particularly the border pieces, but whatever.

As for reading the minimum wire and wall sizes/thickness info, I already read. Several times and while I understand what is being said in general, I don't really understand the guidelines in a practical sense, all I've managed to gather thus far is that the wire/wall size and thickness must be sufficient to support the stability and weight of the model etc etc against light handling...

The main problem that I have with this is I have no idea how to easily determine whether or not I'm complying with this as I'm constructing the model so again, not sure what to actually do...

No, it's not going to be just that one side, it will be a cube made of six sides identical to the side that I'm showing (well after some rearranging of the pieces to make them tighter/closer and more connected.

I'm aware of the fragility of the sandstone multicolor material and that is exactly why I'm asking this question now as I don't want to end up with something that just falls apart or whatever.

As for size, I'm thinking of going for a cube that is either 7x7x7 (so roughly the max allowed for a cube) or maybe 5x5x5, inches of course, and I don't think I'd aim for less than 5x5x5 because i think if I did so then there would be too much of a risk that the pieces would have walls too thin or whatever...

I'd just try to make sure that the dimensions of all contact areas are at least close to the minimum wall thickness (measure in your software or in netfabb studio basic) and plan for initial "rejection" by shapeways personnel when they do the manual pre-production checks after you order the item. The automatic "thin walls check" visualisation after uploading the item may already provide a few hints, but it is rather coarse and easily misled by surface details. Uploading a design does not commit you to anything - but you will see how your current model is interpreted by shapeways' software and above all get an automatic quote for what could be an expensive object given its size and solidity.

Thanks!

That's exactly what I'm doing, I'm rebuilding the model and then uploading in increments to Shapewise to check the wall thickness as I progress.