Everything You Need to Know about the Formlabs Fuse 1 SLS 3D Printer

By Sean Charlesworth

Sean's take on the Fuse 1 3D printer from his visit to Formlabs' announcement event.

Earlier this month, Formlabs brought me out to the MIT Media Lab for The Digital Factory, their first digital fabrication conference in conjunction with Desktop Metal. At the event, Formlabs unveiled its Fuse 1 SLS printer and we were given an exclusive behind-the-scenes look of the machine. Here's everything we know so far about how it works and the prints you can get out of it.

Photo credit: Formlabs

The Technology

Selective Laser Sintering (SLS) uses a laser to bind together thin layers of a powdered medium (typically nylon) to form a finished model. The finished nylon model is very strong and can have relatively thin walls while retaining strength and flexibility. Any powder that is not sintered by the laser acts as support for the model allowing complex geometries to be printed successfully. Additionally, the entire volume of the print chamber can be packed with models - unlike other technologies that can only utilize the surface area of the print bed. When finished the print is encapsulated by all the loose powder in the build chamber. The print must be allowed to cool in the chamber as it will remain somewhat pliable until cool. The chamber is emptied and all the loose powder is cleaned away from the print. If the model is hollow it will need drain holes in order to remove any loose powder.

Due to the printing process, SLS parts will have a slightly rough surface texture and won't resolve very fine details as well as SLA resin prints. However, prints will be much stronger than most resin prints and cost less. In addition, parts do not need post-curing and are not UV-reactant like resin parts.

Typically SLS technology has only been available as large, industrial machines at $150,000+ so a four-figure benchtop unit is pretty exciting. While Formlabs isn't the first to introduce a benchtop unit at a price under six digits, they are the first U.S. based company to do so and at $10,000--a very reasonable price for a SLS machine.

How the Fuse 1 Works

Keep in mind that the Fuse 1 is still getting the finishing touches, so some details may change once it is released.

The Fuse 1 is about the size of a mini fridge with a build chamber of 165mm x 165mm x 320mm and 100 micron layer resolution. It can run off a standard 15-20A 120V circuit and uses a 10W fiber laser to sinter nylon powder. Initially available materials will be Nylon 12 - an industry standard - strong and with some give and Nylon 11 - a slightly more pliable material. Powdered nylon is added to the machine via a cartridge locked into a feed hopper on the top.

Build chamber removed with platform lowered

The build chamber is heated to bring the nylon powder close to the melting point. This process takes about an hour from a cold start. The 'print bed' is actually a removable build chamber with a platform that moves downward for each print layer. A precision roller distributes a thin layer of powder across the print area and the laser sinters the cross-section of your model. The platform moves downward, the hopper feeds more powder and the process repeats. The build chamber can be completely filled with parts top-to-bottom and side-to-side with no need for supports as the loose powder does that job. Also, additional models can be added to the print job during the print process!

Sintering in action

The Fuse 1 has an internal camera that monitors the print bed, and it's very satisfying to watch the laser sinter each layer. There's a large touch screen up top that allows full control of the printer as well as viewing models loaded for printing. Connection is via ethernet or Wi-Fi via an updated version of their excellent PreForm software.

Cleaning/Reclamation Station

Once the print job is done the build chamber can be removed and allowed to cool as the prints will be warm and slightly pliable. Eduardo Torrealba, Project Lead for the Fuse 1, said that the industry standard is to let the cartridge cool for the same length of time the print took but they have been doing it in half the time with no issues.

Now we get to one of the downsides of SLS printing: the mess. The parts need to be dumped out of the build chamber along with all the loose powder that acted as support. There will be users who come up with their own systems for dealing with this but Formlabs has provided an option with the cleaning and mixing stations. The cleaning station shown in our video is not the final version and is still under development. It will interface with the build cartridge to monitor the temperature for proper cooling of parts and then raise the platform - pushing out the models and powder into the cleaning area. The perforated bed will allow loose powder to fall through as you clean the parts with brushes and air power. A dust mask is a recommended safety precaution but I suspect the finished product will be fully enclosed.

Fuse 1 with the Mixing Station

Reclaimed powder will filter down to an empty cartridge that can be moved to the mixing station where it is combined with new powder for reuse. A typical mix of 50/50 new and used will give good surface quality while a higher mix of used, up to 70%, can be used at the expense of some surface quality although strength will remain the same. I appreciate the fact that Formlabs has provided an option for the post processing AND made it an option as it will run an additional $10,000. For those trying to start up a small print service or business they may buy just the printer and come up with their own post processing system. For those wanting the full setup it will run $20,000 which includes the Fuse 1, two build chambers, the cleaning station, mixing station, 10 kg of powder, extra empty cartridges for the mixing station and a pro service plan. The internet has expressed some concerns about handling the nylon powder, breathing it and potential dust explosions. Formlabs has been working on the Fuse 1 for over three years and they assure me all safety precautions are being considered and addressed.

Print Quality

The prints coming out of the Fuse 1 look great. Those familiar with SLS prints typically see them in white, Formlabs is using a dark gray which absorbs more of the energy from the economical fiber laser for better fusing. We saw very strong prints such as the drill housing and bike pedal which can be put into direct service. A big advantage of the SLS method is really nice print-in-place parts such as chains, pivots, joints etc that come right out of the printer working.

Brian Chan's Iron Man Gauntlet - fully funcitonal right out of printer

The Iron Man gauntlet by Formlabs engineer Brian Chan is an excellent example of what can be achieved with SLS. It comes out of the printer fully assembled with working joints and has some really thin, yet strong features. Take the time to check out Brian's impressive work on other projects such as the 3D printed violin and his articulated creatures.

Chainmail Bodice - collapsed to print fully-assembled CREDIT: Nervous System

Another great example is the chainmail bodice by Nervous System which not only prints out with all the links connected, but is collapsed and packed to fit within the Fuse 1 print volume.

Fuse 1 vs EOS Print

Formlabs offered to do a sample print for me, so I sent my Buckaroo Banzai jet car which I have printed many times on the professional EOS SLS printers. While this print is optimized for SLS printing - hollowed, proper wall thickness, etc - it is also a bit of a torture test with lots of different angles and cross sections, as well as fine detail. Formlabs managed to squeeze the job in just days before the Fuse 1 unveiling and overall it's a great print. It had to be shrunk down slightly to fit in the build chamber and notice the black deformation on the front bumper - it was printed on an earlier prototype machine that had the limit switch adjusted differently, so the print stopped with only a few layers to go.

Dark Gray Fuse 1 - Black EOS

The Fuse 1 print (dark gray) took approximately 22 hours to print, is strong with no warping of large flat surfaces and most of the details resolved well (look at the tire treads). There are a few surface blemishes and irregularities but they are minor. You'll notice that details on the EOS print (black) are a bit sharper for various reasons. The EOS is an industrial machine costing well over $150,000 and the model has also been tumbled--a process using abrasives to smooth out and clean the surface even more. This can also be done with the Fuse 1 prints as well but has not been done on the Formlabs jet car. Finally, the Fuse 1 has not been released to Beta yet, so they are still tweaking settings. I anticipate that a jet car printed a few months from now will look even better.

Our Take

Formlabs have proven themselves with the Form 2--the amount of software, firmware and material upgrades over the last year has been impressive. As with the Form 2, the Fuse 1 is well thought out with great attention to detail and usability and I look forward to seeing how it progresses over the next few months. Obviously, at a $10,000 price point, this is not a machine for everyone and a powder printing system can be messy. But under the right circumstances this machine is a perfectly reasonable and obtainable expenditure.

Small businesses who want to prototype or even manufacture parts, such as small print services, architecture firms, makerspaces, etc can make great use of a machine in this price range and it should pay for itself quickly. Another factor to keep in mind is that while you may not be able to afford the machine, at this price point local fabricators and print shops will have them which will make SLS printing more accessible and cheaper for you to use as a service. You might be able to walk into a local shop and talk to an actual person to get your prints done.

While the complete $20,000 system with cleaning and mixing stations, extra build cartridge and service plan is ideal, it's nice that there is an option to buy just the printer for those adding more to the print farm or those on a tighter budget who want to develop their own post-processing systems. The final material cartridges are still in development but pricing should be around $100/kg - the build chamber holds about 5.5 kg.

Fuse 1 Beta units are scheduled to go out toward the end of the year with production units shipping sometime in 2018. Stay tuned as Tested will be getting a system to try out--Zorg ZF-1, anyone?

Check out our behind-the-scenes video of the Fuse 1