Practical 3D Printing: Printer Performance

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Printer Performance

09.09

00:00	While covering the different forms of resin 3D printers in the previous module, we briefly touched on a few performance metrics like resolution and print speed, but in this module we'll take a deeper dive into the key factors in SLA printer performance and the metrics that we can use to compare them.
00:16	Not only will these be beneficial when we're trying to get the best results for our projects, but they'll also be the main considerations if you're looking to purchase a printer of your own.
00:26	Let's start with what's likely the first metric people consider when looking to invest in printers, and that's the cost.
00:33	There are many affordable options for SLA printers.
00:36	Most consumer grade or hobbyist options are in the range of a few hundred dollars up to a thousand or so USD.
00:43	And these are absolutely capable of providing very usable results.
00:48	More professional equipment can be in the multiple of thousands or even up to tens of thousands, but of course the sky's the limit with CNC machines and there's examples of printers costing well into the hundreds of thousands.
01:02	This doesn't mean that we shouldn't keep these expensive units in mind as many companies now offer 3D printing services using these, meaning they can still be of use to us without actually owning them.
01:13	More expensive usually goes hand in hand with larger build volumes, increases in resolution and overall build quality.
01:22	The technology used has some impact here, although we'll mostly be focusing on LCD MSLA printers.
01:29	Just like we discussed with FDM printers though, there are many other things that factor into the price like customer support, market and location to name a few.
01:38	Workflow and ease of use also come into play here, but again since we haven't been able to test every offering on the market, we can't comment on specifics and your best source of information here is word of mouth or online reviews.
01:52	Before moving on from the topic of cost, we should discuss the main consumable cost being the resin.
01:58	We'll cover all the different options for resin in a dedicated module soon, but these are usually somewhere in the vicinity of 100 US dollars per kg, making them around 2 to 4 times the cost of most filaments for FDM.
02:12	So, it's fair to say that even though the machines could be in a similar price range, resin 3D printing is usually a bit more expensive.
02:20	However, they shouldn't really be compared like this as they offer different advantages.
02:25	This brings us to the next point, which is what resin printing is known for, a smooth surface finish and high resolution.
02:32	The surface finish is really a result of the core process as we discussed in the previous module, as each layer is chemically bonded to the next, but this is also determined by the quality of the printer and its performance, the material used and the resolution.
02:47	This is where laser powered SLA printers gain their advantage, albeit at the cost of print speed.
02:53	Because the laser projects a round dot, any curved part can be truly round and perfectly smooth.
03:00	DLP or LCD MSLA printers are limited here as they project the light through voxels or pixels, and historically these would cause a stepping in the surface finish.
03:11	However, more recently these printers are starting to use extremely high resolution projectors or screens, some of which the pixels can be partially turned off, reducing this stepping effect considerably to the point where the surface finish is much the same as you'd get from a laser powered SLA printer.
03:29	The resolution will be specified by the manufacturer, generally being something like 4k, 6k, 8k or even up to 12k.
03:38	All this really tells us is the number of pixels in the horizontal direction across the screen, but it doesn't take into account the size of the screen.
03:47	For example, a larger 8k screen can have approximately the same number of pixels as a smaller 8k screen.
03:54	So, the resolution per area of the larger screen, is worse even though they both sold as 8k.
04:01	What's more important is the xy resolution.
04:04	For laser systems, this is a function of both the size of the laser and how precisely the position of the beam can be controlled.
04:12	For DLP or LCD, this comes down to the size of the micro mirrors or pixel size, and the smallest feature that the projector can reproduce on a single layer.
04:23	The smaller this number is, the better the resolution will be.
04:26	This will usually be in the range of 20 to 50 microns for most consumer grade MSLA printers.
04:33	The z-axis resolution is easier to understand.
04:36	This is the minimum layer height that can be printed based on the z-axis movement.
04:41	The idea here is just like what we discussed for FDM 3D printing, but the layers are much smaller, even down to a tenth of the thickness of the smallest that's possible with FDM.
04:52	While the smaller layer height increases detail and surface finish, it also increases the print time and the chance of errors.
05:00	So, in the end, it always comes back to the application.
05:03	Better resolution isn't going to be of much benefit if we're just printing simple parts with minimal detail.
05:09	Let's move on to cover some other metrics that are a bit more straightforward to compare.
05:14	The first being the build or print volume, essentially what size part can be printed.
05:19	From our discussions on FDM printers, we'll be familiar with cubic measurements.
05:24	For example, 240mm.
05:26	250mm3 where the printer will be limited to a 250x250x250 cube.
05:33	MSLA printers are a bit different here because the print volume will almost always be expressed with three separate measurements as they're almost always different.
05:42	An example of this would be 218x123x235mm.
05:49	The first measurement of 218mm is in the x direction or the width of the build platform.
05:55	The next measurement of 123mm is in the y direction or the depth of the build platform and this is almost always smaller than the width.
06:04	Finally, we have the 235mm measurement which is in the z direction, essentially how far the build platform can move vertically.
06:13	And it's not uncommon for this to be the largest of the three dimensions, but all printers are different.
06:19	Most of the printers we'll be interested in purchasing will typically be smaller than 300mm in all of these dimensions.
06:27	All other things being equal though, larger print volumes will be better if we have the space for a larger machine.
06:33	But as always, we should consider what we'll be using it for.
06:37	If we don't need the extra size, then the extra cost of a larger printer wouldn't be justified.
06:42	The other easily comparable metric is the print speed, which is also one of the key advantages of resin 3D printing over other additive manufacturing methods.
06:52	While the technology being used has a significant influence here, some printers can simply print faster than others, and if the printer is capable of doing this without sacrificing quality, then this is naturally going to be beneficial and boosts efficiency.
07:07	Finally, let's cover the printable materials.
07:09	And this also differs between printers like FDM.
07:13	The various materials offer different properties and therefore open the door to different applications for the parts.
07:19	What materials are printable is less clear cut than with FDM printing though, where this is mostly governed by the achievable temperatures of the machine.
07:28	Many SLA 3D printer manufacturers will make and sell their own resins, which is always recommended as the machines are calibrated specifically for those resins, so the results are generally going to be better.
07:41	Other manufacturers will allow for third party resins to be used with an open platform system.
07:46	This is great if we're looking for alternatives, but in some cases the properties of the print can suffer.
07:52	Before purchasing a printer, it's important to review the spec sheet and ensure it's a good fit for your application.
08:01	We'll be coming back to cover these in more detail in a dedicated module.
08:06	There are many other features and metrics used to compare printers that have a significant impact on their performance and usability, but we've covered the main ones, so let's recap the key takeaways.
08:17	Outside the build quality, technology and print engine used, or other supplier specific factors, there are a range of metrics to determine the performance of each printer.
08:26	The build volume determines the maximum size of part that we can print in a single piece, and the print speed determines how fast we can complete a print.
08:36	The resolution determines the level of detail that we can print, and it might not be as simple as manufacturers would like us to believe.
08:44	Be sure to consider the X, Y and Z axis, not just the number of pixels on the LCD screen.
08:50	Outside of these core metrics, there's a seemingly endless amount of features and variations between them that may or may not be relevant to your application.
08:59	So, as always, we need to understand our requirements alongside the printer specs and the material options available.