Guide

First look at the Original Prusa XL: CoreXY with an always-perfect first layer and plenty of new features!

Hello everyone, here’s the BIG news many of you have been waiting for (some might say that Friday came a bit early). 😉 I’m happy to give you the first look at the Original Prusa XL, our upcoming large-scale CoreXY 3D printer with a 36×36×36 cm (14.17’’ cubed) build volume, next-generation extruder, new hotend, segmented bed, and a tool changer!

There are some crazy features packed into the XL (like an always-perfect first layer!) and I can’t wait to dive into the details because the new printer has much more than just a large build volume. Nearly every aspect of the machine has been designed completely from scratch and it is truly a beast!  Currently, it’s scheduled to begin shipping in Q2/Q3 2022 but we’re launching preorders now. However, they work differently this time around with a refundable deposit instead of paying the full price upfront – there’s more info below.

Essentially, the XL is something completely different than just an upscaled MK3S+. You can even consider it to be a bit of a showcase for our future 3D printers. 😉 So let’s jump right in!

Building a Prusa CoreXY

There were a number of variables we had to consider when designing our first CoreXY printer. The first one was, obviously, the right size. We settled on 36 cm (14.17’’) cubed – for a number of reasons. The larger a printer is, the more prone it is to vibrations and other unwanted effects that translate into bad-looking prints. So, building a larger MK3 would have no actual benefits. On the contrary, in fact. Using the same design would bring a number of headaches to deal with – a large heavy heatbed moving along the Y-axis, less stability with higher Z-axis values and so on. CoreXY was the way to go.

36 cm cubed is more than enough for a vast majority of large objects – you can, e.g., print a cosplay helmet in one piece easily, or produce detailed architectural models. There’s another important aspect to consider with massive objects: the larger the print is, the longer it takes to finish. We’re still tweaking firmware and print settings to tell you the max speed, but you can be sure that thanks to the small and lightweight direct-drive extruder the XL can be very fast. Just an upfront note: we are aiming for print quality, not looking to join the SpeedBoatRace.

However, we are considering an unsupported, but official Klipper firmware for those looking to find the limits. Either way, no matter how fast the XL will be in the end, huge prints (several kilograms) will still take days to finish. Rest assured that we’re implementing all the proven features from our current 3D printers to reduce the stress from long prints – like power panic and filament sensors, for example.

Plus, there are various practical additions like telescopic filament spool holders on the side of the printer, which can hold up to 2-3kg spools – they will be needed because the XL can chew through a regular filament spool in no time. There will also be optional addons (draft shield/enclosure) available, which will be revealed later.

 

New segmented heatbed

With the dimensions set, we could also finish developing another one of the cutting-edge features: our new segmented heatbed. Why not simply use a scaled-up version of our standard “MK52” bed? Every time I see a large-scale 3D printer producing something small, I can’t help but think how wasteful it is to heat up the entire huge heatbed and burn through kilowatts of energy any time you want to print something. Our new heatbed with individually controlled 9×9 cm segments is not only energy-efficient (you can turn on/off individual pads) but also effectively reduces warping thanks to its expansion gaps between each segment. To explain it a bit: regular heatbeds have a tendency to warp as the temperature increases. The problem isn’t very evident with smaller surfaces and can be partially compensated for with mesh bed leveling. However, once you have a large heatbed, the issues become more noticeable.

We can do all sorts of things with the segmented heatbed – like alternating heating of individual segments in a checkerboard pattern (via PWM), which reduces the load on the PSU. One of the obvious benefits is the possibility to heat only some of the 16 heatbed segments in case the printed object is small enough.

Needless to say, the segmented heatbed was not developed just for the XL. With these 9×9 cm segments, we can scale up or down our machines as required. Did anyone say Prusa XXXL? 🙂 I think nobody noticed it yet, but even the printers we’re showing at EXPO 2020 Dubai are using these pads – just in a 3×3 pattern.

But I think it’s time to get to another star of the show!

The Nextruder and always perfect first layer

The XL is equipped with our new next-gen extruder, “Nextruder” for short. It took us nearly three years to develop and, honestly, there are so many new features, it’s difficult to find the best one to start with.

So let’s kick off with something that will be visible every time you start a new print: we utilize a highly precise load cell sensor to deliver an always-perfect first layer. Instead of an off-the-shelf load cell, we have developed our own system. It is embedded within the solid single-piece heatsink and it allows us to measure the physical load on the heatsink. As a result, we can use the nozzle as a sensor to “probe” the print surface. We use analog data readings, which gives us precise information to work with. BTW – years ago, I actually had a load cell in the i2, positioned between the extruder and the hotend to measure force needed for extrusion. Good old times… 🙂

So, in layman’s terms: we can utilize the load cell system to perform an incredibly precise height calculation for the first layer. No matter whether you just swapped the nozzle or the print sheet – you don’t need to recalibrate anything. There’s no need to adjust Live Z, no manual calibrations, or any sort of complicated nylock mods to achieve a perfect first layer. It simply works every time and it’s a joy to watch it happen. If I exaggerate a little bit, theoretically you could stick a plank of wood into the printer and it would still create a perfect first layer. Don’t do it, though! 🙂 Anyway, this means you can soon say goodbye to fiddling with the first layer and Live Adjust Z!

 

However, the load cell sensor allows us to do more than that. We can now recognize a jam in the nozzle and pause the print. In the future, one of the things we want to focus on is the ability to detect a partial jam – so the printer could notify you in time before the actual jam happens. And maybe even detecting if the print has come loose from the bed.

 

Gear up!

To further upgrade the print quality, the extruder now features a brand new, internally developed zero-backlash cycloidal gearbox with a large no-slip drive gear. Wow, it just rolls off the tongue, doesn’t it? 😀 This system replaces the previous solution with two small grooved gears and allows for greater control of how the filament is fed into the nozzle. In fact, we implemented a bit of an overkill solution – a 20:1 gearbox. It performs well above the power we see in most other extrusion systems on the market and delivers extremely high pushing force. And it works amazingly well.

The Nextruder also features a brand new electronics break-out board with a dedicated CPU and a stepper driver, so basically, everything in the extruder connects directly to this board, which is then connected via a single-cable interface to an easy to swap connector on the edge of the new custom 32-bit motherboard. We’ve also added another thermistor into the heatbreak. This allows us to adjust the temperature according to the material spec and also detect heat creep.

 

The nozzle, which has been developed in cooperation with E3D, is embedded inside an entirely new assembly that allows you to easily pull the entire hotend (with all-metal parts) out of the extruder. The nozzle is connected to a metal tube, which prevents various issues arising from insufficiently tightened nozzles. Making the nozzle easy to swap was key because we want to give you more options to print with nozzles of different sizes – e.g. use a larger diameter for more durable objects and faster printing (comes in handy with a large-scale 3D printer). To be clear, while it may sound familiar, this is different than the Revo system.

While I could write much more about the Nextruder here, I want to keep some things for later. 😉 Let’s move on!

The right tools for the job

Because XL is a CoreXY machine, adding tool-changing capabilities is something that kept coming to our minds. The result is that the machine can operate with up to five independent tool heads.

We have developed a kinematic coupler mechanism that doesn’t need electromagnets or other active elements to work. The system is extremely precise and features a fully automatic tool alignment calibration ensuring that after every tool change everything is perfectly aligned. The system is also based on the load cell sensor – no more tedious calibration prints, everything is automated. Printheads will just tap a small calibration pin and configure offsets automatically. Check out the video because it shows everything in action!

There are also sensors ensuring that the tool head has been successfully swapped. We’ve been running internal head-swapping tests for several months already and we’re over half a million successful tool changes without a single hitch.

Because changer supports up to five tool heads, it means that you can: easily print soluble supports, print with up to five colors, or use vastly different materials (because each nozzle can be preheated to a completely different temperature). We’re even thinking about mixing different nozzle sizes in a single print to shorten the print time. Of course, we’re considering other tools as well, not just extruders.

If you simply need a large-scale printer, then the single-extruder version is the one for you. However, everything is ready for an upgrade, so you can run up to five tool heads. Once you install the optional tool changer mechanism, you can easily swap between two tool heads. For three to five tools, you’ll need to add an expansion card. This way, you can upgrade your XL gradually over time to suit your needs.

Coming in 2022

Announcing a new product in these trying times is still rather difficult – I’m sure you read it everywhere: a shortage of components, long delivery times and other issues. While we’ve already set out on a journey to produce as many parts as possible in-house (we even bought SMD assembly lines!), we need more time to set everything in motion. Right now, we’re still dependent on several third-party suppliers and sourcing parts for development is no easy task. On the other hand, we simply couldn’t keep you in the dark any longer and we wanted to finally showcase what we’ve been cooking for so long in secret.

 

Due to the ongoing uncertain situation with components and delivery times at hand, we decided to set the start of XL manufacturing to Q2/Q3 2022, so we can also secure enough components to start production. By default, we will offer three versions of the XL in our e-shop: Single head, dual-head, and the full five-head version. Please note that with 3+ tool heads, there’s a price jump because of additional hardware needed. Based on the current situation, we’re targeting the following prices:

  • Single toolhead semi-assembled – $1999 (vat excl.) / 2099€ (vat incl.)
  • Dual toolhead semi-assembled – $2499 (vat excl.) / 2599€ (vat incl.)
  • Five toolheads semi-assembled – $3499 (vat excl.) / 3699€ (vat incl.)

The price of the fully assembled version of each variant will be $500 more. Should this change at any point, we’ll post an update.

It is very important for us to know the demand now so we can secure the additional components as soon as possible. That’s why we’re launching pre-orders on our new e-shop right now. But this time, we’re doing them in a different way. Instead of paying the full price right away, there’s only a refundable deposit of $200 USD. This way, you can secure your place in line (which we think will be again pretty long…). Once your printer is about to be shipped, we’ll contact you and you will be able to fully edit your order – change the printer configuration (e.g., select the number of tool heads), add accessories and filaments. The reservation fee will be, of course, deducted from the total price of the order. This way, we can also better scale our production based on the demand.

So, that’s it for now, the last announcement in this year. We’ll be back later to share more details about the XL. Meanwhile, you can check out the store page in our new e-shop, and if you’re at the Formnext exhibition in Frankfurt, you can see the XL in action in our booth number A127!

Happy printing!



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