My initial experience with a 3D printer came in 2020, when I got access to a buddy’s Creality LD-002R SLA printer. This was one of those awkward transition phases for SLA printers, where inefficient RGB LCDs finally got replaced by monochrome LCD panels, thus massively reducing the required exposure time and increasing the LCD panel’s lifespan.

The closely related Creality LD-002H is a monochrome SLA printer, but as this wasn’t the one that this friend opted for we had to learn the ropes on this more old-school printer. In terms of specifications this meant a build volume of 119 mm x 65 mm x 160 mm to play with and a claimed 26.1 µm resolution. Despite some struggles along the way, this machine churned out impressively high levels of detail with whatever cheap resin we threw at it, and even the post-printing processing became easy once we added a flex plate to the build plate and tweaked the cleaning and curing steps.

Despite all these positives, we both drifted away from resin printing, mostly due to the still messy and smelly printing process. FDM printers seemed like a better deal, especially after said buddy got his mittens on a used IDEX FDM printer. I would eventually go through a rather loathsome Creality Ender V2 experience before ending up with my current-day Elegoo Neptune 4, and resin printing seemed to be a thing of the past for me. Until recently, that is.

Things Have Changed

Despite not having access to a resin printer any more, I still kept up to date on newly released hobbyist-level 3D printers of any type, as well as progress in technologies. Here I rather liked the digital light processing (DLP) types of resin printers, as they ditched the LCD and UV light source for a MEMS micro-mirror and laser setup for big power and weight savings. Unfortunately DLP resin printers appear to have fallen by the wayside again due to a variety of reasons, one of them apparently being scaling limitations with available DLP light engines and the manufacturers for the latter seemingly uninterested in this market.

Thus consumer SLA printing is still generally done with mono LCDs, which do not quite have the same efficiency and crisp edges for individual pixels as DLP, but which otherwise have come a long way, with better optics and light sources. A big push has also been towards larger build volumes, so despite new SLA printers tacking on more ‘K’s to their display resolution, the effective resolution isn’t that much better than a 2020 budget model. The real question is probably whether that’s even needed based on my own experiences printing fine details.

Perhaps the most exciting change is that with overall user-friendliness,  such as easier bed levelling, the preventing of resin smells wafting out of the printer into the room, heated resin vats for reliable print results and UV-blocking lids that you can flip open instead of having to gently lift off the printer with dirty gloves while you desperately try not to drop it whilst scrambling to find a free spot to put it safely down.

Although the Creality LD-002R lists air filtration with a carbon filter, this was more filtration of the homeopathic variety. Instead of filtering anything, the tiny, noisy fan effectively blasted unfiltered, resin-rich air into the room. Thus one of the first thing we did was disabling this ‘feature’ by turning off the fan and sealing the air hole. This immensely improved the printing experience even with less optimal airflow in the room.

Picking A Resin Printer

The selection of resin printers to pick from these past years has been nothing short of overwhelming, even if you ignore the veritable flood of slightly different variations from certain manufacturers. Here DLP printers seemed different enough even with their small build space, to the point that I almost got one. Of course the long-awaited successor DLP printers never appeared, and the small build space was somewhat rough and put me off from an impulse buy.

Thus getting an SLA printer as a friend for my FDM printer seemed like the only option, but lacking real project motivation that idea got put on the backburner. It’s really hard to justify a purchase if you cannot justify such a financial expense, after all.

That’s when I suddenly got motivation shoved into my face, in the form of Uniformation contacting me about giving their GK3 Ultra SLA printer a shot. This would be a no-strings-attached chance to have a poke at what looked to be a rather nice and capable printer, even if its price tag of around $1,300 makes it something for people who really know that this is the resin printer they want.

I had heard of this Uniformation company before, as a smaller company that scored a pretty big hit with the somewhat-troubled-but-very-interesting GKtwo SLA printer, which had also featured on my shortlist at one point. The GK3 successor to the GKtwo had been baking in the resin printing community for more than a year by the time I got contacted, with gradual improvements over that time based on community and reviewer feedback.

This is quite different from most 3D printer companies who generally push out a new model in a take-it-or-leave-it sense, so I took them up on their offer for this printer to either play with or use as a very fancy coffee table, whatever I wanted. Based on the sheer verbal abuse I have read aimed at Uniformation during the GK3 development phase on especially sub-reddits, it makes me fairly confident that all major issues were fixed, and that at the very least it’ll be a massive upgrade over the LD-002R that’s pretty much my reference point.

Setting Up

In the world of 3D printers, it would seem that the idea of a flatpack parcel with your new 3D printer – as with my Ender 3 v2 and Neptune 4 bed slingers – has come to an end. A modern CoreXY kinematics FDM printer arrives fully assembled with only few exceptions – like Prusa 3D’s DIY kit offerings – so you’re looking at a very big box that weighs a lot. The similarly priced Prusa CORE One+ for example comes in at a cool 22.5 kg without packaging.

The GK3 Ultra ups that to 35 kg, so I had a rather unhappy delivery bloke lug the ~40 kg box up a few steps from his van to where I could use furniture rollers to walk it over to its new home, next to the FDM printer in a sturdy rack. Lifting the printer into the rack was consequently also a bit of a chore, though less due to the weight and more due to the lack of any good places to grip it. I had to put on some good gloves for extra grip and to prevent the aluminium case from cutting into my flesh.

With that chore done, I could finally admire the fine mess that I had gotten myself into. First of all, the build volume is pretty massive, at 300 x 160 x 300 mm, almost fully beating the Neptune 4’s 225 x 225 by 265 mm. The GK3 Ultra is notably quite deep, at about 40 cm before adding space for the power and Ethernet cables, not to mention the provided Wi-Fi dongle if that’s more your thing.

Much of this extra space is taken up by the resin dispenser system, which I’ll cover more later. Within the rack you’ll need at least 85 cm between the two shelves if you want to put a resin bottle into the slot that’s conveniently placed on the top. Fortunately you can also pour resin directly into the vat and even make the flippy lid removable, but it’s a pretty hefty unit either way.

After liberating a lot of foam and goodies from the inside of the printer, I was finally able to start commissioning it. This involved removing a lot of protective film, running the exposure test to verify that the LCD and UV light source are working, and best of all a quick confirmation that the pre-levelled build plate was still level. Compared to the faffing about with four bolts on the LD-002R’s build plate assembly and sheets of A4 paper that I was used to, this was a massive improvement.

Time To Print

The resin that got sent along with the printer uses a special bottle style, which fits in the GK3’s resin feeding system. You slot the entire bottle into the hole on the top of the printer, from where it should automatically slot into all the tubing and widgets that are supposed to handle the resin flow. My only misgivings with this design is that each of these special cartridge-like bottles are only rated for ten insertion/removal cycles, after which you have to buy a new one.

If you use non-Uniformation resin and are pouring resin into a special bottle, then this can be a bit of a pain, if only to keep track of just how many times you have inserted said bottle before you suddenly have it start draining fully into the vat, or whatever the failure mode here is. Fortunately you can also disable this feature if you’d rather pour the resin directly into the vat, which is probably what I’ll end up doing with typical resin bottles rather than use the provided empty special bottle.

Since the only bottles of non-expired resin that I have lying around use this automatic resin feeding system, I’ll be be giving it a shot. A total of two resin types are available to me, one is the water-washable type that’s supposedly not as smelly as the standard resin that I have always used, and which can be cleaned with plain water instead of IPA.

The other type of resin is ABS-like, which as the name suggests is a ‘tough’ kind of resin, targeting similar use cases as ABS, ASA and kin. For the test I’ll print everything with both WW and ABS, as well as in PLA on the FDM printer, to test both overall workflow, printing of fine detail, water-tight parts, heat-resistance and durability.

Test Setup

For a first printing round, I have so far printed a range of parts on the Neptune 4 in white PLA, and for the GK3 Ultra I will initially just use the ABS-like (AL) clear-blue resin, to not have to switch resins just yet, which is another fun topic to cover. These prints include a range of items like bottles, a miniature figurine and a bunch of LEGO Technic-compatible parts. The latter two serve to give dimensional accuracy a good workout, along with basic durability testing.

The print results and my initial findings will be in the next article, as this one is getting on in words. I’m also more than happy to consider any requests for aspects to test and questions to answer here. Although I have so far printed FDM parts in PLA, I’ll probably also be printing some parts in PETG and conceivably also TPU. Since I only have an open style FDM printer, engineering-grade materials such as ABS, ASA, etc. are naturally not available to me, for both practical and health-related reasons.

 

Magnets are awesome, so it’s no wonder we love to add them to our 3D prints. Doing so in a way that will actually last is harder, with thermal creep being one reason a simple friction fit will loosen over time, and using super glue to hold a magnet in place can be messy. In a recent video, [Slant 3D] covers seven ways to install magnets in 3D prints without resorting to glue, along with the advantages and disadvantages of each.

With friction, the argument is that you can still use them, but you’d want to use something like cylindrical magnets rather than flat magnets to increase the friction with the thermoplastic. Using an arbor press rather than human primate hand power is also beneficial.

Rather than installing magnets halfway through a print with all the logistics that entails, you can use side slots to install said magnet into, which is much easier, but as with all embedded magnets, you get that plastic barrier between the magnet and its target.

Other methods involve using a bit of extra material that you need to push the magnet past, using something like an arbor press, so the magnets should never just fall out. A wildcard here: spherical magnets, which can be locked in using a similar method, while automatically orienting themselves to an opposing magnet.

The final tip is to never use two magnets in a magnetic lock. Instead, use a cheaper ball bearing or a similar plain metal part on one side instead. Magnets tend to be much more brittle than whatever stainless steel ball bearing or washer you can use on the other side.

Of course, people will always try to install magnets during an FDM print, but before they try to do that anyway, they really should learn about the fascinating ways in which magnets can ruin print beds, destroy nozzles, and otherwise make a total mess of a print. Magnets seem magical. Maybe they are.

One of the most crucial aspects of FDM 3D printing is ensuring sufficient material is extruded. Determining the right flow rate can be done manually, but some printers these days automatically perform this adjustment, which is very convenient. [Stefan] of CNC Kitchen investigates how to add similar functionality using existing bed-leveling sensors.

A major complication with extrusion in FDM printers is that the flow rate has to fit the printing speed. However, you can’t just immediately speed up or reduce the flow rate, as the melting filament is flexible and thus acts like a spring, especially as the extruder is exerting significant force on the filament, which adds compression.

The moment you reduce or increase the speed of the nozzle, you can get over- or under-extrusion, but the delayed response by the extruded filament means that you have to adjust for this change in advance. Ergo, the name ‘pressure advance’, also known as the K-value. Obviously, this is a parameter that differs with each material, printer, and other factors, so a direct measurement is always the best.

In the Bambu Lab X1 FDM printer, a Lidar scanner was used to scan various test patterns to automatically determine the optimal setting. This was later moved to the purge section of the extruder in newer Bambu Lab printers. On other FDM printers, the only available sensor in that area is typically the pressure sensor for bed leveling. Could this sensor make a similar measurement?

This wasn’t just an idle thought, but was inspired by the Snapmaker U1, which runs open-source Klipper, with tantalizing glimpses of how it does pressure-advance sensing in its extruder. This extruder also only contains a load cell, as do some Prusa printers. These much more open printers thus provided a test bed for some experimentation.

With load cell data available, [Stefan] measured how various extrusion rates affect the load cell, which can then theoretically be correlated with the appropriate K-values for specific transitions. He created a calibration tool for a range of Prusa printers that works with stock firmware, though this is definitely still a work in progress. There are also a couple of similar open-source projects, such as this Auto PA Calibration project by [Mark].

Overall, K-value presets tend to work pretty well, but adding a pressure-advance calibration feature to existing FDM printers is definitely an interesting idea. There’s also the prospect of lateral sensing using this same bed-leveling sensor, which could allow the printer to sense much more than just the bed.

3D printing has been around long enough that everyone’s heard at least one weird trick regarding 3D prints. [Angus] of [Maker’s Muse] puts a few to the test, and came away with one solid tip for releasing TPU from a build platform to which it has unfortunately welded itself.

Flexible filaments tend to stick too well to build plates, which is why an interface layer like a thin layer of glue stick is called for. But what if one forgets to apply it before starting a print job? That can result in a print that is well and truly stuck. Peeling flex filament off a textured PEI bed is a bad time, because the print can tear and tends to leave little bits behind.

[Angus] heard that applying isopropyl alcohol helps release things in that case, so he gives it a try. Lo and behold, it seems to work! See for yourself at 18:10 in the video and keep it in mind if you end up in a similar situation. The print doesn’t exactly fall off on its own, but it does remain in one piece which is more than one can expect otherwise.

Watching isopropyl alcohol help release a stuck print is reminiscent of the way it also removes hot glue from just about any surface. The trick is getting the alcohol to wick in underneath for best results, and the same seems to be true with releasing TPU from a build plate.

One thing to keep in mind when evaluating tips and tricks from over the years is that the landscape changes. Something that maybe seemed to have potential years ago might not make much sense today. A good example is sugar as a bed adhesive, which [Angus] tries out. What started as an experiment in getting PLA to play better with glass build plates years ago doesn’t really carry over to now, with PEI-coated magnetic build platforms pretty much a solved problem. The more likely result nowadays is just a mess.

[cmh]’s ultra-simple top cover for the Snapmaker U1 3D printer has a 3D model, but don’t let that fool you. There’s no 3D printing at all involved in this project. Rather, the model is a reference shape for making an effective top cover out of cardboard or corrugated plastic sheet (also known as Coroplast) which is what [cmh] used.

Corrugated plastic is a versatile option for things like printer enclosures. It’s cheap, a good insulator, easy to cut, and available from just about any plastics supplier. We’ve made the case that they’re a good alternative to acrylic sheets for printer enclosures, but [cmh] goes even further with a design that requires no additional hardware whatsoever. Assembly doesn’t even require more than tape, really.

He provides a cutout diagram for pieces that, when assembled, make a sort of hat that is just right to cover the top of the Snapmaker U1 without obstructing the extruders. One can even lift the front panel to access the inside without removing the cover, which is a nice touch. Should one wish to add a viewing window anywhere, just cut out a square and tape a sheet of clear plastic over the hole.

For a 3D printer, an enclosure and top cover helps retain heat, block drafts, and keep dust (or curious fingers) away from the printer’s build area. The cover doesn’t need to be completely sealed to deliver those benefits, but if you do prefer your covers completely enclosed, a carefully-chosen IKEA storage box makes a conveniently great cover for the U1.

Ceramic 3D printers, despite using the same fundamental mechanism as standard FDM printers, are much harder to find. Part of this comes down to the material properties of fired ceramics versus thermoplastics, but they’re also significantly harder to build; for example, in his ceramic printer build, [Joshua Bird] had to deal with severe material shrinkage, collapsing bridges, and the surprisingly abrasive effects of clay.

The centerpiece of the printer is the clay extruder: an air compressor pushes clay along a tube into the extruder, which uses an auger to squeeze the clay through the nozzle, while a gap at the top lets trapped air escape. The extruder has enough control for successful retractions, but rheology remained a challenge: the clay needed to be soft enough to flow through the nozzle, but stiff enough to form bridges without collapsing. [Joshua] thus pressurized the clay as much as possible, making it possible to use stiffer clay mixtures. The extruder’s greatest challenge was longevity: [Joshua] tried many 3D-printed plastic augers, but the clay abraded them all much too quickly, often in under an hour of use; a 3D-printed stainless steel extruder solved this.

Printing in ceramic isn’t a simple process: for each part, [Joshua] had to mix the clay, load it into the tube, clean the extruder, actually print the object, let it dry, fire it, apply glaze, and fire it again. The clay’s shrinkage during drying and firing destroyed many prints, but [Joshua] was nevertheless able to print a double-walled cup, a decorative climbing-themed cup, and even a chain-mail mesh.

The 3D printer’s motion system is a polar design, an adaptation of his earlier non-planar 3D printer, which might eventually make it easier to print overhangs. We’ve previously seen a similar auger-based clay extruder, an approach reminiscent of direct-granule FDM printing.

Of all innovations adopted by the maker community within the past couple of decades, one stands among the rest on top for anything regarding manufacturing. It goes without saying here at Hackaday how many projects have been reliant on using the technology to turn their ideas into reality. 3D printing has been a maker community invention and, in return, has expanded this hacky community into something that anyone with an imagination can get into. It also goes without saying that the layer-based tech imposes limits on what we can actually create: think overhangs and layer adhesion. However, there’s a possibility that a recent offshoot of this scrappy community has the power to eliminate some of these faults.

Volumetric additive manufacturing (VAM) is a young technology that has a similar start to many new tech toys, including the original SLA of the first 3D printers. That is expensive and completely stuck in the laboratory… Fortunately, that’s not where 3D printing as a whole stayed, as the RepRap project managed to bring the obscure technology to the hobbyists’ main stage. An entire group of people formed and spent countless hours until the useless pieces of poorly extruded plastic could form parts impossible to make with anything else. A cool quirk of history is that it likes to repeat: examples spur recreation, and this appears to be happening with the technology found within VAM printing.

History

Hold up for a second. While we have covered VAM here before at Hackaday, it’s not exactly the most well-known tech or the easiest to understand. So what is it? Starting from the beginning and simplest forms, VAM is similar to the more  common SLA printing. Using a light source and light sensitive resin, both of these methods can create entire physical objects by solidifying or curing specific areas of a vat or vial of resin. SLA will often use something like a laser and layer by layer “draw” the model until the entire geometry is finished. A quirk of most of many photosensitive resins is that they need to overcome a threshold before they can start curing. This allows VAM to do something a bit different. The earliest methods of VAM used intercepting lasers which allowed selective curing only where these beams were intercepted. One singular spot at a time would be able to overcome the threshold required for printing, allowing you to build up most geometries.

This works, but for more complicated models there’s more effective methods. One type has been covered here before called Xolography, still using intercepting beams, however with differing wavelengths which allows for more finite control. This is effective, but the resin is complex, requiring two-wavelength-photon-sensitive photoinitiators. Introduce the current standard in VAM printing, computed axial lithography (CAL). This method finds itself using existing methods found in traditional tomography, such as CT scanners. CAL methods are basically reverse tomography, where a model is used to create projections to be projected in printing. These projections allow dose control in each “voxel” of resin from changing the projection as the volume of resin is rotated. When ideal, this means that the entire model is printed at once. No layers needed for printing, and printing in minutes rather than hours.

Open-Sourced

Cool, but why should you care about this tech? Because you could start using it now! Just like the RepRap project before it, VAM has OpenCAL. OpenCAL was started by the same lab that originally created the axial version of the technology. UC Berkeley released the first OpenCAL around 2019 which was… well a start.

Functionally practical for only big budget research, it was far too expensive and complicated for any hobbyist with a 9-5 to realistically touch. Last year saw a new model presented at Open Sauce which used a consumer projector and common hobbyist electronics. While this was an improvement, there are three barriers to VAM printing; the hardware, software, and chemical resins make it a challenge for any individual alone. A newer version of the hardware was quickly put together for this summer. This helps with the hardware element, but there’s two new aspects being released alongside OpenCAL V2 for other unsolved problems.

 

Software: Tomo

For a little while now there have been various software packages available for allowing easier use of whatever VAM printer you might have, however these had various problems. From being undocumented to being complicated for anyone without comfort in command line , something different would be needed. A standalone application would certainly work, and low and behold that’s exactly what’s being tried here, called Tomo. Tomo allows you to use an OpenCAL printer with little thought or expertise, or ideally any other type of VAM printer.

Chemistry: Formlabs Resin

Material science is always a particular challenge for the open source community. Unlike software, you can’t distribute unlimited copies of your perfect mix of photosensitive resin without special chemical clearances and certainly not for free. Some of the first 3D printers from RepRap would use a nylon weed wacker line in place of the standard PLA of today. Unfortunately there’s less flexibility in the fine tuned resin found in VAM. This resin has to have a nonlinear photo-reaction for selective curing, be fairly transparent to the reactive wavelength, and be very viscous to prevent resin movement during printing. Formlabs, which makes resin printers and resins, has gotten into the act. Through talks between the OpenCAL team and Formlabs, an agreement for production of this special resin is being worked out, allowing for far cheaper material.

Hardware: OpenCAL

Of course this leaves the printer itself. OpenCAL is designed for a variety of different sized printing volumes, projectors, or anything else you might have in mind. Expect printing anything from this printer to finish in the span of minutes. While it can do the same small prints found in the older model of OpenCAL, experiments involving larger form factors have been attempted. But if you want more details make sure to check out the documentation here or join their Discord channel!

Future of VAM Printing

So how far can this technology really go? Could it pass traditional methods of 3D printing? Well, it’s certainly faster than traditional printing, however, there’s still plenty of trouble when trying it out. How do you remove partially cured resin off your print? How do you actually tell when the print is done? These are problems that are being fixed right now by the community, and maybe you can be the one to fix something holding it back. It’s fair to say that the community that has propped this technology up to where it currently stands is who is going to decide where it goes.