May 12, 2023

Formlabs Form 3+

The Formlabs Form 3+ is a stereolithography (SLA) 3D printer geared to professionals. Formlabs describes the Form 3+ (starts at $2,499; $4,249 as tested) as an industrial-quality desktop 3D printer, particularly good for rapid prototyping by product designers, as well as parts production. Indeed, it is capable of printing high-quality parts, and the Complete Package that we tested provides a full 3D printing solution (except for resin and sandpaper). You may find that there is a considerable learning curve in mastering the Form 3+, however. Formlabs' customer service is responsive, though, and helps to resolve problems as they crop up, which means the Form 3+ can be a powerful and reliable tool for your workbench.

I first encountered Formlabs at World Maker Faire New York more than a decade ago, when the company's first 3D printer, the Form 1, was in crowdfunding. I remember a representative showing me a 3D-printed chess set made on the Form 1; the print quality of the pieces was impressive, especially compared with the rough-hewn look of prints from many of the mostly filament-based printers typical of its day. It seemed to me that Formlabs was on to something special, and the Form 1+ was one of the first 3D printers—and the first SLA printer—that I reviewed. My experience with it convinced me of the promise of stereolithography in terms of print quality and resolution, while also revealing this method's many challenges.

Stereolithography was the first 3D printing technology to be developed. In an SLA printer, an ultraviolet laser shines into a vat of UV-curable liquid resin, tracing a cross section of the object to be printed on the resin, and in the process curing (solidifying) the resin layer by layer until it forms the printed model. A translucent (but opaque to ultraviolet light) orange hood covers the Form 3+, preventing the resin from being accidentally cured through any appreciable exposure to sunlight. (One can briefly open the cover, say to remove or attach the build plate, without any apparent ill effects to the resin.)

Compared with filament-based printers—also known as fused filament fabrication (FFF) or fused deposition modeling (FDM) printers—the printing process for SLA models is inverted. The build plate—the surface to which the object being printed adheres during the printing process—is suspended upside-down from an arm above the resin tank, into which it is dipped time and again as each layer is printed.

While the Formlabs Form 1+ and Form 2 are traditional SLA printers, printers in the Form 3 series—including the Form 3, Form 3+, Form 3B, and Form 3BL (the latter two geared to the healthcare industry)—use low-force stereolithography (LFS). LFS is an SLA variant that drastically reduces the forces exerted on parts during the print process, according to Formlabs. It does this by combining a flexible resin tank with an improved light processing unit (LPU) where the laser beam is generated. LFS is said to produce smooth parts with fine details and sharp points.

In addition to the printer and build plate, the Form 3+ includes a finishing kit containing two small tanks for dunking prints, plus tools and nitrile gloves for handling the resin and isopropyl alcohol (IPA). That's everything found in the Basic Package, while our test unit is the Complete Package, which adds washing and curing units (which Formlabs calls Form Wash and Form Cure). Formlabs sells the Complete Package for $4,249 directly, but you should check with your preferred 3D printing supplier to see if a lower negotiated price is available.

When a print is completed, the build plate ascends to the top of the printer, and the build plate with its object still attached can be unlatched and placed in a holder at the top of the Form Wash, which holds approximately two gallons of IPA. Alternatively, you can place an object that has already been removed from the build plate in the wire basket, as shown in the photo below, for the wash process. Both the printer (when the hood is in place) and the Form Wash (when closed) are well-sealed, so I hardly ever noticed fumes from either the resin or alcohol during the printing process.

Once the top of the Form Wash is closed and the user starts a wash by pressing a button at the bottom, the machine will churn the alcohol, rinsing the object. When the 20-minute rinse cycle is done, the user can remove the object and place it in the Form Cure. The unit heats the object to 140 degrees F, then cures it with UV light, a process that takes about an hour.

Setting up the Form 3+ is simple, at least in principle. You attach the build plate to its arm, which is done by pulling a lever up, sliding the plate into place, and then depressing the lever. You then plug in the printer and turn it on. Next, tap the printer icon at the top left of the LCD screen, and you'll see a diagram of the printer showing the status of the resin cartridge, build platform, and resin tank.

The resin tank comes in a tray, with a lid made of the same UV-opaque orange polymer as the printer's hood. To install it, you open the hood, remove the tank from its tray and take off the lid, then insert the tray into the lower part of the printer, working it toward the back until it clicks into place. You then seat the mixer bar (which stirs the resin) on its carriage on the left edge of the tank.

Finally, you take a resin cartridge and put it in the cartridge receptacle at the back of the printer, opening the top valve by pressing it down (as you would the pressable valve found on shampoo bottles). If all is in order, the cartridge, platform, and tank on the the LCD screen will glow blue.

The Form 3+ can connect directly to a computer via USB, or over a network via Wi-Fi or Ethernet. I did all my test printing from my computer over Wi-Fi. To connect the printer to Wi-Fi, you identify your network (the same one that your computer is on) from the list of available networks accessible through the printer's settings, and enter its password, which it will save.

To prepare an object for printing, you open it in PreForm, the company's 3D printing software, which is available as a free download. Its operation is similar to Ultimaker Cura and other 3D printing programs you may have used. You load a file (in STL or OBJ format), and the object will be rendered in the virtual build area onscreen. You can move, resize, and duplicate it; change its orientation; and automatically fix issues it identifies.

It may prompt you to add supports to keep the object stable and well-formed during printing. You can add a full raft at the bottom of the print, or mini rafts around each support. You can click on the Job Setup menu to select the printer, and make sure its resin type, resolution, and other settings are correct. When you are satisfied that all is in order, tapping the printer icon in the vertical menu at the screen's left-hand edge will send the print to the printer and then launch the print.

At least this is how the printer operates in theory. In my experience, various issues cropped up along the way. For starters, the tray was not identifying the cartridge, and vice-versa. I emailed our Formlabs contact, who let me know that our test unit comes with a one-year service contract, which includes a a representative giving a 45-minute introduction to the Form 3+. So I availed myself of the introduction, which was helpful—in addition to getting a good overview, I was able to ask various questions related to the printer.

I also made two calls to the company's service line, which were equally helpful. For instance, regarding the seeming cartridge-tank incompatibility, I discovered that a tank becomes paired with the cartridge it is first used with (though it can be reprogrammed). This makes sense in that you don't want to accidentally mix resin types, but it is true even before any resin has been poured into the tank. This is compounded by the fact that the tank and cartridge must each make an electrical connection with the printer, and the tank connection in particular proved balky; it required several attempts until it was properly seated, and a little more force than I would have applied had I not been told that it might be necessary.

Another issue was in getting the tank to fill during the priming process in preparing for the first print. I was told that I would save a lot of time if I manually poured some resin into the tank after removing the cartridge from its bay in the back of the printer, and once the resin reached a certain level, reseating the cartridge. Although I did this, the resin still would not flow from the reseated cartridge. After another call to the help line, I shook the cartridge (more vigorously than I had in the initial setup), manipulated a valve on the cartridge's underside, and stirred the resin (with a chopstick). Now the tank filled, but very slowly. I found out that this particular 10K Rigid resin was tricky to work with, since it contains glass particles, which help its rigidity but also add to its viscosity. I shook and stirred the tank again, and squeezed the bottom valve, and this time I could print with it. I soon switched (using another tank) to the draft resin.

Formlabs sells a variety of resins in liter bottles for the Form 3+, ranging in price from $149 to $299. (Other resins, such as biomedical ones, are not suitable for this printer.) Selecting resins appropriate for your work is one task you will want to do your research on, and perhaps speak to a company representative before you buy.

Another issue I encountered was difficulty in removing completed prints from the build plate, even when using the supplied scraping tool to try to pry them up. I found some pointers to facilitate object removal from the build plate in Formlabs' online help resources—ironically, both heating and cooling the object and build plate were on the list. Of the two, putting the object and build plate in the freezer (after bagging them, to protect any food from the mildly toxic resin) for a couple of hours seemed to work the best. We did not have a chance to test Formlabs' Build Platform 2 (a $229 accessory), which allows you to flex a metal sheet that covers the platform. This lets users quickly and easily remove objects from the platform without tools, according to Formlabs.

Another related problem concerned the proper type of raft and supports, in light of the fact that prying the print off the build plate may be no easy task. Although supports can usually be easily clipped and/or pulled off the print, if the raft breaks while you're trying to remove it from the plate, supports attached to it may be wrenched in an unexpected direction, potentially breaking delicate parts such as a leg of the lunar lander shown above—I left the supports attached to that print to show what a thicket they can create. This is more of an issue with large objects than with small ones that have relatively few supports.

All told, I printed nine test objects, seven using gray draft resin and two with white 10K Rigid resin, and all at 100-micron layer height. There were no misprints. Once a print was launched, it continued until completion.

One of the objects we use for 3D printer testing has text and geometric shapes that are rendered on a sharply inclined surface. It turned out exceptionally well. The shapes and text were well-formed, and although it looked like a layer was skipped in two places, that was only apparent when I looked at it from up close.

I had originally printed the same object using supports and a full raft, but felt that the presence of supports interfered with the goal of the test, and removing supports broke some of the finest detail on the print. I reprinted the object with neither supports nor raft; such props proved to be superfluous as the quality of the reprint was magnificent. Some objects, though, require supports, and mastering their use is a learning process.

Even a Grogu (baby Yoda) print turned out surprisingly well. While larger such prints we've produced using filament-based 3D printers often have poorly formed fingers and ears, the Formlabs Grogu print was nearly perfect despite its diminutive size.

I also printed several more small objects with supports; they were easy enough to clip, and sanding removed any real trace of them.

Early stereolithography 3D printers were enormous contraptions costing in the five- or six-figure range. But Formlabs has been at the vanguard of creating relatively affordable, professional-grade desktop SLA printers. The Form 3+ supports a full low-force SLA 3D printing workflow nearly out of the box, though you have to buy the resin and a few extras such as sandpaper separately. Moreover, it produced high-quality prints in testing.

Don't expect everything to work smoothly from the start, though. You may well need to make several calls to the company's phone support representatives, who we found to be helpful overall. Mastering this powerful yet complex product takes some time—we could have easily spent a few more weeks testing it—but the results are worth the effort.