# Printing orientation for multiple small objects in a single file

Discussion in 'Technologies and Hardware' started by henryseg, Dec 1, 2012.

1. henryseg Well-Known Member
So we don't currently have the ability to specify the printing orientation for our models. However, I'm wondering if there are ways to play the probabilities to get the correct orientation.

Specifically, I'm planning to print many copies of a small object, and I can choose the orientation of each of them in my model. I could put a third of them with 'up' pointing along the x axis of my model, a third pointing along the y axis and a third pointing along the z axis. If I did this, I know that two thirds of my models would come out correctly. Alternatively, I can have all of my models pointing the same direction, and hope that it is printed in the correct orientation. For both of these plans, the expected proportion of good models would be 2/3 of them.

Here's another thought: What if I arrange the objects in a way to maximise the chance that it will be printed in the correct orientation? Suppose for example that I arrange the models so that they are lined up as a long stick, rather than being in a cube. In fact, suppose that my stick is so long that it won't fit into the machine other than in exactly one orientation. Then knowing which way this has to appear in the machine, I can choose the orientation of each of my objects in the stick so that they will definitely be printed correctly.

Would that be evil?

Last edited: Dec 1, 2012
2. henryseg Well-Known Member
Here's a related question:

Suppose I have a model whose bounding box is a regular cube, with the same length, height and width. Then, presumably (?), it couldn't possibly help Shapeways to rotate the object before printing. So in this case, could I assume that the printing orientation would be the same as it appears on the model's page?

3. stonysmith Well-Known Member Moderator
Is it an "actual" box, or is there open space to it?

Take a look at this picture... the object on the left is rather plain but it doesn't fill the entire bounding box. When the packing software goes to assemble a job, it may very well setup two of them stacked as you see on the right. This way, even if the bounding box was a certain size, the top copy still would get flipped over to make them "fit".

This is to say, you don't get the whole bounding box volume "to yourself".. I know that I've seen small items stacked INSIDE a Ring Poem Candle Holder during a build.

Be aware: if we impose on Shapeways the requirement that things be printed in our specified orientation, it will reduce the number of items they can put in a single build job and will (to a degree) add to their cost to print the things.

4. henryseg Well-Known Member
Ah, so that's interesting: I wasn't sure if the packing algorithm just used the bounding boxes for the models, or looked at the shape inside as well. I guess that there's also a human element as a last check for sanity.

Another question: If I have the choice to collect my 50 small objects together into a near-cube shape, or line them up as a long "stick", which is actually better for Shapeways? I had assumed the former would be better, but thinking about it more, it isn't so obvious to me. Does Shapeways ever split up a file of many small objects into parts, to better fit into the machine around other things?