One problem testing out this printer is that it has capabilities that no other printer on the market has, so you can get caught between two problems. Firstly, it’s very easy to get caught up in hype about things that later turn out to be just gimmicks. And secondly, it can be hard to see the full value in features until a wide range of people have had the chance to flex their creative muscles and really find great uses for them. We’ll do our best to steer a path between these two issues.
The five extruders can each be loaded up with a different filament. These can be different colours of the same filament, in which case they can print multicolour objects in a very similar way to other multicolour printers. However, it can do more. Because each extruder is entirely separate, you can use different types of plastic. There are some limitations – for example, the print bed will be the same temperature, which might cause a problem for some mixtures of filament.
The XL can mix rigid plastics, such as PETG, with softer plastics like TPU. We got a couple of test models from Prusa with which to try this out. One was a print-in-place box that included a flexible, water-resistant seal. The other was a CT scan of someone’s wrist with the bones printed in PLA and the bones joined with flexible tendon-like rods printed in TPE. Both of these prints printed excellently, and have a wow factor that, honestly, we’ve not seen in 3D prints for a long time.
While the test prints designed by Prusa are undeniably impressive, we wanted to see how hard it was to conceive and design something ourselves that made use of this mixture of materials. The two things that we came up with are a keyboard support with integrated rubber feet, and a phone case. Both turned out well, though we would like some more powerful tools in PrusaSlicer for placing filament.
The keyboard support could, we’ll be honest, have been a print entirely in rigid plastic with rubber feet glued on. This would have worked perfectly well, but we wouldn’t have been able to get feet in the shape of a lizard this way.
The phone case is another matter. We’ve tried 3D-printed phone cases a few times on other printers and never had much success. We’ve found that any filament that is flexible enough to provide some impact resistance is also stretchy enough to fall off the phone. We combined rigid and flexible material so that there was a sturdy frame around which we put soft flexible filament (40D on the Shore hardness scale). The result is a case that fits securely and snugly, while still providing a lot of impact resistance. We think there’s still a little way to go before we’ve nailed this case design, but it’s already by far the best 3D-printed phone case that we have had.
Another option is to mix different materials for supports and the main print. This can be as simple as using a cheaper material for supports – or more advanced like using two plastics that don’t stick, to create supports that are easier to remove (such as PETG and PLA). There’s even the option of using a soluble material such as PVA for supports that just wash away. This isn’t currently well-supported by the slicer, as it causes a problem we don’t fully understand with the wipe tower. Hopefully, a future version of PrusaSlicer can help with this.
function Tool changers are fundamentally complex mechanisms. There’s a reason that there have been so few available to buy over the years. While they are conceptually simple, there is a lot of detail to get right. To get the layers consistent, each tool change has to be accurate to within a tenth of a millimetre or so, otherwise the layers will be at slightly different heights, and it has to do this over and over again. In the worst case, there could be 20,000 tool changes in a print and every one has to be spot on. The machine also has to be able to keep doing it print after print. That’s a big ask.
Initially, we did have a little difficulty with the different extruders having slightly mismatched Z-heights, which resulted in some filaments being too squashed into the print bed on the first layer, and others being too far away. We followed the calibration guide and still had the problem. We solved it by both lubricating the tool changer, and unloading the filament before doing the tool head calibration.
The only other issue we’ve had is getting some large blobs of filament protruding above the top of the wipe tower. This seems to happen when the extruder primes but doesn’t move, so squirts a blob in place. The next time it uses the wipe tower, it then has to bump over this blob. It makes a bit of a clatter as it does so. At first, we were so paranoid about this that we kept checking on the printer and snipping off any big blobs with a pair of side cutters. However, after a while, we just got used to them being there. It looks pretty horrible, but it’s on the wipe tower and doesn’t seem to cause any problems.
speed It felt like 2023 was the year that 3D printing became fast. Almost every 3D printer was judged on its ability to create a Benchy in minimal time. The XL is actually a really hard printer to judge on speed. When it comes to straight one-filament speed, it’s reasonable, but not spectacular. There’s a lot working against it. Frames with larger print volumes inevitably have less rigidity, and the tool changer both increases the mass of the print head and places it further away from the axis. The end result is a single-colour speed that’s slightly slower than the MK4.
A Benchy is probably about the worst case for speed on the Prusa XL, as it contains a lot of small moves that benefit smaller machines that won’t flex as much under high accelerations. The best case is something that has a lot of colours on every layer because the tool changer can switch filaments far quicker than most other printers.
For an example of this, we took a one-inch cube and coloured each face differently (other than the top and bottom). The Prusa MK4 isn’t yet compatible with the colour changer (though it is in the works), so we’ll use the Bambu Lab X1-Carbon as a comparison. This printer is no slouch and is probably the fastest off-the-shelf hobbyist printer. However, the XL can print our multicolour cube over eight times faster than the X1 with the same layer height. This is a phenomenal speed-up, but even this is understating it – we limited it to four colours because that’s as many as the X1 can do. The XL can do an additional colour.
The only honest answer we can give about speed on the XL, compared to other fast high-end hobbyist machines, is that it’s somewhere between slightly slower and eight or more times faster, depending on what you want to create. Therefore, if you want a printer for speed alone, it’s really important to look at the actual models you intend to print, not just isolated benchmarks cooked up by reviewers. However, we can say that if you do plan on printing with multiple colours, you are likely to get a significant speed-up, particularly if there are a lot of colours on each layer.
Another significant speed-related issue is the ability to print lots of things at the same time. While the time to print one Benchy on the Prusa XL is about the same as printing it on the MK4, you can fit nearly three times as many on the print plate. This might seem a bit surprising, because a 36 by 36 cm print bed doesn’t seem that much larger than a 25 by 21 cm print bed, but it really is. The speed-up here isn’t from the printer taking less time per Benchy, but from you, the user, not having to come and take things off the print bed as often.
Obviously, this does come with the risk of one failed object on the print bed damaging all the others, but you can cancel an individual item within the print without having to cancel the entire lot.
quality The quality of prints we’ve had from the Prusa XL is good, but not perfect. It’s not uncommon for multicolour prints to get a bit of the wrong colour filament in the wrong place. This is due to a bit of stringing, or a blob from the wipe tower, being picked up by the nozzle. It doesn’t happen much, and most of the time it’s easy to clean up.
software support Overall, we’d say that the Prusa XL is as well-supported by the slicing software as most existing printers. However, the tool changer opens up some whole new possibilities that we’re only just getting our heads around. For example, embedding text or a logo in one colour onto a surface of another colour looks great, and you can do this in PrusaSlicer, but it’s a bit clunky as it involves creating a new part and merging them. It’d be far easier if you could just do this in the same way you can emboss text or SVGs onto a part.
We also had an issue in one print where we used the colour paint tool to apply colour to the surface of an object but, on a curved surface, the colour didn’t go deep enough and the underneath colour shone through a light-coloured upper layer.
Another minor problem encountered was when an object is made of multiple different parts in CAD and then merged, it can become impossible to properly select some of the parts to paint them.
In all these cases, the problem can be solved by going back to the original CAD files and manipulating them there before going into the slicer. However, we’ve gradually moved away from CAD to the PrusaSlicer as it has been upgraded with more and more powerful tools for manipulating 3D shapes, and we’d like to keep moving in this direction.
These are all relatively minor issues, but we’d hope that the colour and filament selection options in PrusaSlicer get some attention soon, as it feels like there are some improvements that could really help people get to grips with this printer.
waste We can’t ignore the fact that 3D printers use plastic, and plastic pollution is a major source of pollution for the planet. Despite some claims to the contrary, PLA is not biodegradable in any realistic way. It is possible to recycle it (and other 3D printer filaments), but it’s not particularly easy and few recycling centres will accept it. That doesn’t mean we can’t enjoy 3D printing as a hobby, but we need to think about our impact on the world.
The Prusa XL uses dramatically less plastic when printing in multiple colours than traditional multicolour printers
. The exact amount will depend on the model, but it can easily end up using less than a quarter of the filament, especially for small models and those with lots of colours. Potentially the savings are even greater if you don’t use the wipe tower, (though this option relies on having very dry filament). Not only does this save plastic, but it also saves you money. A heavy user of multi-material prints could easily find that the XL is actually a cheaper option compared to a classic multicolour printer, when considering the saving in filament over the life of the printer.
The Prusa XL is a hard printer to review, because there’s so little to compare it against, especially now the E3D tool changer has been discontinued. The large print volume and weight of the tool changer slow it down, so it’s not the best for large, single-colour prints, and it is probably the most expensive printer we’d still consider fitting in the ‘prosumer’ hobbyist category. However, it can create prints that no other printer can. This will probably prove true in ways we can’t yet predict as people get their hands on the machine and start experimenting with creative ways to use the capabilities. On top of this, for multicolour prints, it’s massively faster than the competition, and the lack of waste is both an environmental win and a money saver. This isn’t a printer for everyone, but for some people, it’s absolutely the perfect printer.
Verdict
10/10
Pushing the boundaries of what 3D printers can do.
