Monochrome LCD Screen

The update was prompted, Prusa Research says in their release blog, by the Original Prusa SL1S Speed’s key feature: a monochrome LCD screen. Monochrome LCDs are lauded in MSLA 3D printers for their fast curing (due to increased UV exposure) and longer lifespan compared to RGB screens – which featured on the SL1.

The company claims the Original Prusa SL1S Speed’s new LCD screen will last four times as long as RGB displays. It’s also replaced the SL1’s UV LED panel with an LED array it says is “four times more powerful.” According to Prusa, users will see layer cure times as fast as 1.6 seconds for opaque 405nm resins (“more than three times shorter exposure than the SL1”) and even 1.4 seconds for transparent material.

Prusa seems to be targeting industrial users with this new release, having dedicated a paragraph of the release blog post to what the faster curing means for heavier industrial resins, specific industries, and where the SL1 is already being used in industry and academia.

Fast Tilting

Printing speeds were not improved on the Original Prusa SL1S Speed by curing time alone, oh no. Prusa also looked to platform movement and decided it just wasn’t keeping up. Vat tilting and platform movement are “nearly three times faster” on the SL1S Speed, the company says.

Vat and build platform motion certainly take a lot of printing time, but getting the motions right is crucial. Do it wrong and parts will remain adhered to the vat too stiffly and break or come off the build platform – causing prints to fail.

Tilting mechanisms on resin trays are great because they limit the surface force exerted on a part at one time. Where parts are removed by the build platform’s Z-motion alone, the full surface is tugged off the vat at once. When tilting is employed, only small sections of the part undergo force in succession.

Print Volume

At 5.96”, the Original Prusa SL1S Speed’s LCD screen is bigger than the SL1’s and has a 25% larger build volume to match. This brings the SL1S Speed’s print volume to 127 x 80 x 150 mm. Prusa says that it can reach over half the total build height, 80 mm, in just an hour of printing, given the right conditions (transparent resin with low layer heights) and points out the usefulness of this speed for prototyping. This means you’ll be able to use the full 150 mm build volume in just two hours, which Prusa says specifically further down in the blog post.

Ball-Screw Z-Axis

The Z-axes on resin printers like the Original Prusa SL1S Speed see more use during regular operations than with FDM printers. Between each layer, even with tilting mechanisms, the Z-axis needs to rise, releasing the last cured layer, and come back down, pushing the part back against the vat.

If Z-motion is inaccurate, you’ll see some real quality drops. Ball-screw-driven axes are expensive but undergo less friction than the leadscrew-based motion typically found on FDM printers and more affordable resin printers. Less friction is already great for longevity but, in a system like resin printing, limiting friction where other forces are present can make a big difference to accuracy – so we’re happy to see a high-quality Z-axis on this new printer.

Swappable Resin Tanks

If you aren’t already engrossed in SLA 3D printing, it might not be immediately apparent that materials aren’t the only consumables. As UV light passes through an FEP film on the lower side of the resin vat the film degrades, becoming increasingly clouded. At a point quality will start to suffer. For some 3D printers, this means replacing the whole vat. For others, just the FEP. Prusa’s given both options with their upgrade here, offering affordable vats with an easy-to-replace FEP film and a tank cover for safely storing materials away from daylight.

This is just a quality-of-life upgrade, to be sure, but it’s a big one. When you’re locked into using a single vat one way or another, changing materials is a cleaning nightmare. Even if you have multiple tanks ready to go, storing them securely and away from the sun’s curing UV rays can be a nuisance. Prusa Research has redesigned their tanks with a graphite-PA6 compound that comes with a lid for secure storage and stacking (stacking!). They’re available for just ~$25 a pop. Opting to replace the FEP film is even cheaper at ~$15 for 3 pieces, but Prusa also says that non-proprietary FEP is fine.

Further Features

• Angled Build Platform -The build platform on the Original Prusa SL1S Speed now has an angled top – “by popular demand,” Prusa says. As SLA printers operate, some resin is inevitably tossed around inside by suction, stirring, or whatever forces are present. Some of that resin can end up on top of build platforms; beveled platforms allow the resin to drip down and back into the vat. It’s a small touch, but a nice quality-of-life upgrade from the SL1’s flat platform.
• Activated Carbon Filter – Nobody wants a smelly printer. Activated carbon filters go a long way in absorbing odors and contaminants, so working nearby the Original Prusa SL1S Speed shouldn’t crinkle your nose too much. Keep in mind: though activated carbon filters are present in air purifiers this does not mean it removes all toxins here. It’s best to keep 3D printers away from spaces you spend a lot of time, and definitely not where you sleep.
• Fully web controllable – The SL1 was Prusa Research’s first fully web controllable 3D printer and that feature has, of course, carried over to the SL1S Speed. The company’s web UI, Prusa Connect Local, is an OctoPrint-like interface convenient for starting workflows remotely. Bear in mind, however, its current form will only function over a local connection (LAN). This won’t be a system that lets you start or stop print jobs from home like some professional web interfaces – at least until Prusa makes that available.