The Carbon Fiber Printer: Markforged’s Mark Two review!

Sometimes traditional 3D printing just doesn’t cut it – that’s where the Mark Two from Markforged comes in! Using continuous fiber inlays together with high-performance Nylons, it creates parts that can compete with metal. Too good to be true?

The Markforged line of 3D printers is limited to their own Eiger software, each machine only uses one type of expensive, specialized filament, the carbon-fiber inlay process and a few other great parts of the machine are locked-down by patents, and this machine is 13 and a half thousand US dollars before tax. But you get to use Elmer’s washable school glue on the printbed. Still, if you’re trying to decide between this and a $200 Prusa kit, that’s probably going to be an easy decision. But if you can make use of the awesome fiber-reinforcement tech that Markforged uses you’re probably not going to care about these points too much anyways. And for everyone else, come along for the ride, because the Markforged Mark Two is just a magnificent piece of engineering all around.

Markforged offers quite a few different 3D printers today. The “lower end” offerings start with the $3500 Onyx One, which is basically this machine right here, with a printhead that exclusively uses the Nylon-based chopped carbon fiber ONYX filament. While that’s already quite a nice material, the interesting bits start to come into play as you move up to the Onyx Pro, which adds that two-part toolhead that lets you print continuous fibers, in the case of the Onyx Pro only Fiberglass. Which means, unlike the bare ONYX material or other chopped fiber filaments, you actually get those longer, continuous strands of fiber layed into your parts. Obviously, these fibers do make your prints much stiffer and stronger, but more on that in a second. And as the ultimate machine in the desktop lineup, you’ve got the $13,500 Mark Two, formerly called the Mark Two Enterprise, which adds support for more fiber materials, such as carbon fiber, high-temp glass fiber and Kevlar. This machine also has the option to print with plain Nylon, which is more flexible and less abrasive than ONYX. For the price, you also get a ton of consumables, two spools of each fiber and a full spool of each base Nylon. And that’s exactly the machine i have here from German reseller Mark3D. Unfortunately, i do have to return it.

As even higher-end options, there’s also the Mark X with a larger print volume and integrated laser scanning, or the Metal X, which is a totally different printer that processes stainless or tool steel, aluminum, inconel or titanium. Pretty crazy stuff! But for now, let’s stick with the Mark Two.

So this is a desktop machine with a print volume of 320 by 132 by 154mm or roughly 12 by 5 by 6 inches. You get a touchscreen display in the front of the machine, an acrylic front panel that you lift open and an aluminum lid up top for better access to the extruder and the rest of the mechanics. And can we just take a second to appreciate how well this entire thing is built and how gorgeous it looks? Starting with little things like how they use these tiny dowel pins to align the linear rails, the way they’ve got machined aluminum and brass everywhere on the machine, the fact that the entire printer is super rigid and once you close the top lid, all of that engineering porn is hidden out of sight and it just becomes this minimalistic tech piece that’s going to look good pretty much anywhere.

On the back of the machine, we get power in, USB, Ethernet and WiFi, since the Markforged machines are pretty much exclusively web- and cloud-based. Yes, you can still use a USB thumb drive to ferry print files between your computer and the printer, but i’ve found that the integration with their Eiger cloud slicer works really well. Essentially, you open up a Chrome browser, upload your stl files to their service and all the hard work happens on Markforged’s side from then on out. Eiger will suggest print settings based on your part’s geometry, such as infill ratios or extra support material, and there’s not much else for you to go in and tweak or tune, as you would be able to do with most other 3D printers. I do like the simplicity of the interface, it provides the right options that you’d use regularly and leaves everything else locked-down for Markforged to optimize. Aside from the base material settings, you can, of course, also decide whether or not and how much continuous fiber to use in the print. Though the fiber algorithms don’t feels that sophisticated yet, as they will always try to lay down full loops of fiber throughout the entire layer and only let you control which layers should receive how much fiber and not specifically which areas of the model should be reinforced. It’s best suited for simpler, chunkier parts as finer details will often throw it off and keep you from using fibers exactly where you’d like them. The software will always try to encase the continuous fiber in a roughly one millimeter thick shell of the base material since the fiber toolhead doesn’t lay down the fibers too precisely. For the most part, though, using the fiber inlay is straightforward and works as intended. Once you’re happy with the part, you can either add it to a print queue to print later or send it straight to the printer if the materials loaded in the machine are the correct ones and the printer knows that it’s ready to go.

Eiger also supports versioning of your parts and print settings, and if you don’t like the 100% web-based approach, you can either leave your printer offline and, again, use USB drives for print files and firmware updates, or optionally get an offline version of Eiger. There’s no support for alternative software and slicers, but the print files do look like a standard gcode file with a very simple compression.

So how does the fiber inlay process work? It’s similar to dual-extrusion, but not quite. The base material is printed with a fairly standard extruder and hotend setup, which comes with a hardened drive gear in the extruder and brass nozzle with a hardened insert in the hotend. Which is nothing that you couldn’t reproduce on any other machine so far. But the continuous fiber feeder is a bit more special. The base fiber is a fairly thin filament that consists of the fiber itself, obviously, but is already impregnated with a Nylon matrix that will fuse it to the rest of the print. And this isn’t extruded like a traditional polymer filament, it’s essentially ironed into the layers of the print. You see, the fiber nozzle is fairly oversized for the filament the machine is shoving through it, instead, it’s more or less just tacking it on and then smooshing it down with the hot brim of the nozzle. This is where those not perfectly regular fiber tracks stem from. Once a loop of continuous fiber is finished, the fiber cutter snips it and then either moves on to the next loop or switches back to the base material. And the results do speak for themselves. While the base ONYX material is already a very strong contender both when it comes to print quality in the Markforged machines and effective strength, it is still a material that is a bit less rigid, but also more ductile than regular 3D printing materials. But once you add fibers, you can massively alter and improve the mechanical properties of your print. Adding even a light amount of carbon fiber will turn your parts into fantastically rigid elements, and depending on how much fiber and how much base material infill you use, you can definitely create parts that can compete with ones machined from solid aluminum. In the live unboxing, I casually broke this sample print in half and then compared it aluminum, and the force required to snap or permanently deform them felt very similar. If you want to check out the full Filaween episode on the Onyx material and how it changes with extra fiber, you can do that up here.

Now, you might have noticed that i didn’t talk too much about the pure Nylon material yet. Well, first of all, like many Nylon filaments, it’s quite soft and probably not too useful for a bunch of applications, but it also turned out that you have to decide which material you want to use with your machine and then stick with that. Because as it turns out, not just the nozzle, which you can replace, but the entire toolhead wears in for the ONYX material, and once that process is completed, Nylon just won’t print well anymore. Markforged quotes about one spool of material for this process to start, but in my case i was already seeing some degradations with Nylon after about a quarter of a spool of ONYX. So either you stick with Nylon and keep your toolhead fresh or you go all-in with ONYX and allow your printer to wear in for that material.

However, i was also seeing some artifacting with ONYX, which i believe to be either a software bug, or an issue with this particular review unit, which had it underextrude on the outside of the print when i tried reducing the number of outer walls to 1 to allow for continuous fiber to be included in parts that would otherwise not have enough space for the minimum fiber length between cuts.

But again, that was something that only showed up in, well, extreme cases. Other prints with the recommended print setting worked flawlessly, every time.

And that’s something i really have to praise Markforged for, not just the Eiger platform, but also the printer itself and the interface on its comparatively small LCD screen just feel and work great, they are streamlined and efficient to use, everything is where you’d expect it be and it just works. I know, some people hate me for that phrase, but really, it just works and Markforged are making sure that you do things right when operating the machine. For example, the bed leveling wizard has you using two precision shims to adjust the printbed and goes over each adjustment spot twice. Yes, it doesn’t have auto bed leveling, but with these smart lever-style adjustment points, if you set the bed adjustment points correctly once, you can even remove and reinstall the bed as often as you want, it just snaps back into place perfectly each time. Nozzle swapping is also something you might eventually have to do, and they are including a tiny socket wrench with a torque limit so that you tighten the nozzle perfectly each and every time. E3D should really start selling these. And during printing, the machine regularly runs to the endstops just to check that it didn’t lose any steps. If it detects a shift, you,ll get an email, just like when a print successfully completes. Stepper drivers in here are Trinamic, which are great, plus a Texas instruments DRV8825, i think for the extruder, but that has quite a bit of stepper whine to it, which most of you might not be able to pick up.

Filament loading and unloading makes use of convenient wizards on the LCD as well, though, admittedly, that will still take a bit of practice to do perfectly, as the fiber really wants to unwind once you take the tape off, and the filament inside the drybox also tangled itself a few time while i was printing. Markforged have already reduced the spool size to 800cm³ instead of 1000 to make that less likely to happen, and, obviously, adjusted the price as well. Yes, both Nylon and Onyx need to be used in the included airtight Pelican case since they are highly hygroscopic, and, i don’t know, this is the one part that just doesn’t feel right, having this dingleberry attached to the printer just doesn’t feel as sophisticated as the rest of the machine does, and it’s not like the Mark Two wasn’t hard enough to pick up and carry around already.

Now, price. I’ve covered the printer’s base price, which is already pretty hefty, but there’s just nothing else to compare it to. There’s no other machine that does continuous fiber. However, filaments are a bit less proprietary, so we have something to compare them against, and yeah, they’re not cheap. Both the Onyx and the base Nylon clock in at more than twice as much as the most expensive Nylon and Carbon Fiber Nylon filaments from other manufacturers, and the fibers come on these 50cm³ mini-spools, selling for between $75 before tax for glass fiber and $149 for carbon. While the continuous fiber is used relatively sparingly, of course depending on how you set up your print, you can still easily triple the printing costs by adding continuous fiber. Which is probably worth it for a lot of professional applications.

While there’s no DRM or cartridge system keeping you from using other filaments on the Markforged machines, and you could even use Markforged’s base materials on other printers as it’s just a standard 1.75mm size, they still heavily advise against using third-party materials, especially when using it with continuous fiber. There’s not even a way to adjust the print temperature, and while, theoretically, you could just grab another carbon-filled or plain Nylon, you should be aware that you will be signing away any reliability and strength guarantees from Markforged as well as warranty claims, at least for the toolhead.

And while we’re on the topic of proprietary or non-proprietary choices, for that matter, let’s talk about patents – and i know this machine is geared towards industrial customers, where, by and large, the value of your company is measured by how many patents you own. In this case in particular, i find it sad to see the technology getting locked behind closed doors for the next 17 years or so, especially since this and most other printers only exists because core patents for FDM 3D printing expired a few years ago and everyone starting jumping on FDM-style printers. The carbon-fiber inlay CFF technology the Markforged machines are using is awesome, it’s a an absolute game-changer for functional 3D prints, as you suddenly get to use a much cheaper 3D printing process where you’d otherwise have to maybe go with a sintering process or CNC machining, where setup costs alone make up a huge portion of the price of a manufactured object. So again, particularly because this approach is so awesome and, yes, revolutionary, I’d love to see a few more companies working on it and maybe getting a bit of competition going, though, i don’t know if that’s going to happen. Well, we’ll see, maybe one day Markforged will go ahead and mark their patent pool as purely defensive. That would be awesome. There’s also a patent pending on some aspects of the bed adjustment mechanism, which is an element of the printer that works extremely well and I’d just like to see it on more machines.

And on a related note, I also didn’t find any attribution for community and open-source work being used in here, particularly around the Beaglebone and Linux system that power the entire experience on the Mark Two itself, there is a bit of attribution given for the Eiger web interface, so… maybe they just missed it on the printer itself?

Alright, so the Markforged Mark Two is definitely a printer that’s unique, that expands what 3D printing can do and it does a tremendous job at it. I really like the printer, i like how well everything clicks together, and things like the web-only, simplified slicer add well to the experience and make sure that using this process doesn’t require you to do hours of training first, most of it is really intuitive and just simplified enough to not be restrictive. The continuous fiber fabrication process, CFF and Markforged’s base materials, especially ONXY, also offer exceptional quality and performance, even if it comes at a price. I was ready to hand out a “Tom approves” badge, but the entire patent topic has me hesitating. If it doesn’t bother you, then the Markforged machines are a great option for a sleek and high-performance 3D printer.

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