Practical 3D Printing: Print Orientation

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Print Orientation

05.20

00:00	One of the most important decisions when setting up a new print project is deciding in which orientation to print the part, and sometimes the ideal orientation isn't the one that's immediately obvious.
00:11	This is technically a setting similar to what we've covered in the previous modules, although there are so many factors to consider here, this topic warrants its own module.
00:21	One of the factors is bed adhesion.
00:23	In most cases, maximising the surface area of the part on the print bed will help with this.
00:30	Having a large footprint of the part on the bed also provides support, keeping the part stable as it's printed.
00:36	In the last module we discussed adding rafts that are printed under the part, and the idea here is the same, increasing the footprint to help with bed adhesion and to provide a solid foundation for printing.
00:48	The next factor to consider is the need for support material.
00:52	If we consider an example part, one print orientation might result in overhanging geometry requiring support material, where a large footprint would be Whereas if we change its orientation, it's possible to remove the overhang and therefore the requirement for support.
01:06	While completely eliminating overhangs and the need for support might not be possible in every case, there will almost always be certain orientations that require less support than others.
01:17	Keeping this in mind can lead to increased sufficiency, essentially minimising material usage and print time.
01:24	The slicer will have rotation and translation movement tools or even features like lay on face that allow us to control the orientation.
01:32	However, print efficiency is something the slicing software can understand.
01:37	So, in most cases, the slicer will be able to automatically orientate or recommend orientations for the print based on these parameters to minimise the build time and the support material.
01:49	Clearly this will be something that we need to review as there are external factors that need to be considered that the slicer just can't account for.
01:57	This is mostly around layer orientation in relation to the application of the printed part, and there are a few things to take into account here.
02:05	The first is mechanical properties, or more specifically, the strength.
02:09	This is something that we'll come back to cover in the design for manufacturing module, but for now just understand that FDM or FFF 3D printed parts are not isotropic in tensile or bending strength, meaning their tensile strength isn't equal in all directions due to how they're built up in layers.
02:28	Typically they're much stronger when the loads are aligned with the layers, rather than trying to pull them apart.
02:34	It makes sense that this isn't such a factor for compressive strength, and the parts are generally much stronger and more isotropic in compression.
02:43	Ideally, when we're designing our part, we'll be able to understand the loads it will be subject to, or at least the directions of the loads.
02:50	So, we can orient the parts so the layers line up with these loads and avoid tension separating the layers.
02:56	Of course, for many FDM 3D printed parts, like prototypes or non-structural applications, they might not be subject to any loads, but we should still consider the layer orientation.
03:08	One reason for this is surface finish.
03:10	As we know, the layer height dictates the resolution, but any walls not perfectly aligned with the z-axis or xy plane will have steps at each layer to some degree.
03:21	If we align the critical aesthetic surfaces of the model in a vertical z direction or the xy plane, then we'll reduce steps on the surface, leading to a smoother finish.
03:32	Gravity should be considered here as well.
03:35	Any surface where supports are removed will feature witness marks, and generally speaking, the underside of overhangs will have a poorer surface finish than the top surfaces or those printed on the bed.
03:47	The same idea applies to accuracy.
03:50	If we're concerned about the accuracy of a certain feature, for example a flange that we want to check accurately bolts up to something else, then we should align this with the xy plane, ideally printing it on the print bed.
04:02	This will provide much more control in the printing process and eliminate the effect of gravity.
04:08	Hopefully it'll be clear by now that all of these factors need to be considered together, and often some compromise is required.
04:15	For example, when aligning layers with the loading direction, we could end up with poor surface finish on some surfaces.
04:22	Settings like layer height can be adjusted to help here, and finishing processes like sanding can also fix the issue, but ideally we'll be trying to achieve the best results straight out of the printer.
04:33	The main points to take away from this module are that print orientation can be used to aid the bed adhesion and provide a solid foundation for stability.
04:43	Print orientation also has a significant impact on print efficiency, allowing us to minimize the support requirements and the print time.
04:51	The slicer will often be able to provide suggestions for the ideal orientation in regards to these factors.
04:58	For load bearing parts, we need to keep in mind the layer orientation, as the parts will be most likely to fail from the layers separating.
05:06	The layer orientation can also be used to control surface finish and accuracy, aligning critical surfaces with the vertical z-axis, xy plane, or print bed.