Practical 3D Printing: Print Orientation & Supports

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Print Orientation & Supports

05.47

00:00	Print orientation is a key topic for SLA printing because, just like FDM, this plays such an important role in the print quality and impacts a lot of key areas like the supports.
00:11	Remember, the orientation is how the part is positioned in relation to the build platform during printing.
00:18	The first thing to understand, which we've touched on already, is that resin 3D printed parts form chemical bonds between the layers, so they're less prone to layer adhesion issues and therefore the resulting print is much more isotropic in its properties.
00:33	For clarity, this means the parts will essentially have similar strength in all directions, no matter what orientation it's printed in.
00:40	There will be some difference in strength, of course, but compared to FDM this is relatively low.
00:46	Of course, this doesn't take into account the actual geometry and design of the part, but that's not the point here.
00:52	The point is that the print orientation has less impact on the strength of the part, like in FDM, and more impact on the print success, being, the print actually finishing without failure, as well as a surface finish and the dimensional accuracy of the part, again, from preventing warpage.
01:10	A lot of the considerations here come down to how the last cured layer interacts with the release film.
01:15	The key idea is really about minimising the release force, which is mostly achieved by minimising the surface area of the cross section.
01:24	The more surface area, the more suction trying to pull the part off the build platform and its supports, but this can also cause surface finish issues on the top layers of the part.
01:34	The film is also a wear item that needs to be replaced periodically, we can get more life out of the film by reducing the forces on it.
01:43	This means we want to avoid having large flat surfaces facing down on the release film, particularly if we want them to look good.
01:51	There are a few cases where the actual area in contact with the film might be low but the suction can still be high.
01:57	For example if the film and the part form an enclosure like a suction cup then the effective area is increased.
02:04	If the cross section is very consistent and stationary though, like with a tall straight part printed upright for example, then the film in contact with the cured resin gets drier with each successive layer.
02:17	The drier it gets, the more the release force increases.
02:20	As a good rule of thumb we usually try to angle the parts by 15-30 degrees.
02:25	which helps reduce the cross sectional area on the film and constantly moves the contact patch to avoid it drying out.
02:33	For some parts this angle will need to be in two axis to avoid any large flat surfaces.
02:38	We just need to keep in mind that this can increase the z axis height and therefore the print time.
02:44	In saying that, it's just as likely that this could be used as a means to decrease the print time for parts that are tall as leaning them over will lower the z axis height.
02:53	The orientation also changes as we go along.
02:55	This is a good example of how to make a screen that is close to the top of the body.
02:59	The top of the body will be in contact with the supports from the top.
03:02	As we have mentioned previously, the supports are required for the same reason as FDM, to hold the part up while it is still printing.
03:09	The key difference is that the supports are attached from above with the inverted SLA printing that we will mostly be using with resins.
03:17	So, the part is essentially hanging from the supports and of course from itself to some degree.
03:22	Supports can also be build between sections of the part and inside hollow parts, not just off the build plate.
03:29	If we don't have enough supports, the part or sections of the part can fall, causing the print to fail.
03:35	The goal is to have the part held very stable to ensure a good quality print.
03:40	With that said, the supports do need to attach to the part, and when they're broken off, this will leave witness marks or marring.
03:47	The more supports and the bigger the support tip contact area, the worse this is, similar to supports in FDM.
03:54	So, we should also avoid large flat horizontal surfaces facing up as well as down, especially if we want these surfaces to look good.
04:03	The surfaces we want the best finish on should be angled away from the build platform.
04:08	Once we have the orientation locked in, we can generate the supports.
04:12	Generally, speaking, we want to minimise the amount of material used and in contact with the part while ensuring that we still have enough support.
04:21	The support density setting and the tip size can be tweaked here, and we can also usually move supports around to make sure they're not directly on important features.
04:31	Remember though, the supports are included in the cross section or exposed area, which we want to keep as consistent as possible to avoid layer lines from uneven curing times.
04:42	So, sometimes more support can actually help here.
04:45	What's most important to remember from this module is that the print orientation and supports are facets of 3D resin printing that need to be created.
04:54	The supports can be thought of together with many shared considerations.
04:57	Print orientation can be used to reduce the need for support and longer print times.
05:03	Primarily though, we want to minimise the release film forces and this is mainly achieved by minimising the cross sectional area and features that form suction cups.
05:12	Any surfaces that we want to have a great finish on should be angled away from the build platform so they don't have supports touching them or face directly onto the release film.
05:22	The support settings like density, tip size and placement can be adjusted to minimise witness marks on the surface of the part while still providing sufficient structure and strength.
05:34	Generally, being able to minimise supports is ideal, but they can be useful as a means of maintaining a consistent cross section and therefore exposure area.