Multiple parts submission and ordering

Hi,
I've had a look around for help on this, but I'm struggling to fully understand how to submit and order objects made of many parts?
Are there any downloadable good examples of objects made of many parts, with an explanation of how to lay out the separate parts before submitting. When I submit an object made of multiple parts, Shapeways wants to merge them into one and I get errors. So should I submit each part as a separate object? Then how do you go about ordering that?

Some basic explanation of this would be really useful. This isn't a question about the actual designing of an object, but the Shapeways side of how do we submit the object and then order it, if it's made of many parts?

I hope that's clear.

Thanks
Chris

Hey Chris,

good question. Its a little hard to know what you're working with here without being able to see it but any parts that are touching will be combined into one part by our software. If you want them to be separate you'll need to separate them with some space.

It depends - if the objects are merged by shapeways' software, their surfaces are probably just too close together. Check the "minimum clearance" parameter stated on the relevant guidelines page under the "Materials" tab. There you can also see if "multiple parts per file" is even allowed for the material in question . If the model is laid out as a kit, it could also make sense to join at least the smallest components with a sprue as found on injection-molded model kits.
You would use multiple separate files when the parts have to be in different materials, or when they are so detailed that a single file would exceed the upload limits (64mb compressed, 1 million triangles).

Here's an example:-

https://www.shapeways.com/product/UH8QH89L8/articulated-pred aking-tail-standard?li=featured&optionId=12497143

Articulated tail. 7 sections, presumably wouldn't be printed actually in position as the parts would be too close together. So if I had made this, I'd have 7 pieces, I'd move them away from each other and bake them there? Do I merge them into, for instance, a single .obj, but not overlapping? Or 7 different objs? Then when uploaded, how are they viewed / ordered if they're separate parts?

Maybe I should just experiment more. I thought there might be a definitive guide. There's information about designing, clearances etc, but I haven't found anything about the process up submitting to Shapeways.

Thanks for the input so far!

Chris

Probably depends on the actual model if it can be printed in position (a shop search for "articulated" will turn up several model of insects and crustaceans printed in place, also see "strandbeest" kinetic sculptures) or as a kit (like the "modibot" or "ersatz" figurines). If parts are so close together that the software wants to merge them, they would fuse during printing anyway. So if this is your problem it could simply be that you overlooked an unintended contact in your model, or a small hole in the mesh that shapeways' software repairs for you in a way that crosses part boundaries. Try checking your model with netfabb studio basic to see what the part count of the unmodified model is, and if it detects any problems that would have to be repaired (warning triangle appearing next to model).

Thanks for your input on this, but this isn't a technical problem I have. I know about building the actual models and the checking for collisions etc.

The question is about the logistics of laying the separate parts out in my app and exporting as objs.
I've knocked up a quick example and some of the issues I'm wondering about:-

This is a hypothetical ball-joint, just to demonstrate my point. Two pieces too close to print actually in place....


So do I place both objects at the origin and export two separate .obj files?


Or do I simply separate the pieces but position close to each other and export in those positions as two .objs?


The other question about that option is do you freeze the individual object transformations (translation) before exporting?

Or do I do this but merge into a single object and output that as one .obj?


Thanks

Chris

Some of this may depend on specific (mis)features of the modeling software you are using, but in essence you would put them (more or less) side by side and export as a single file. As far as I know shapeways can and will even pick individual loose parts from a model and place them somewhere else in the printer volume if they see a suitable hole to fill in that particular run, so how the parts are oriented relative to each other will mostly matter for the auto-generated preview images.

OK Thanks.
I'll probably try some of these options out and see what happens. Merging into a single .obj would make a lot of sense.
Thanks

Chris