Surprise: Prusa Announces Resin 3D Printer, The SL1

Long time non-resin 3D printer manufacturer Prusa Research announced a resin 3D printer.

The company has been extremely successful in recent years marketing a series of increasingly powerful desktop 3D printers that use the filament extrusion process. Originally a unique design founder Josef Prusa contributed to the open source world, he then went on to found a company that efficiently produced units based on that design.

The secret to Prusa’s success has been a combination of these elements:

• A competent machine that reliably produced excellent quality prints

• A low price for the machine, and even lower prices for kit versions

• Great post-sales service, including diagnoses, parts supply and firmware updates

• Ability to inexpensively upgrade the machine with current features

This formula works brilliantly, as the company rapidly expanded as sales of their equipment exploded. The last we heard, the company was producing upwards of 6,000 machines per month. In their recent announcement Josef Prusa revealed his team now includes 320 people. This is perhaps now one of the largest 3D printer manufacturers on the planet.

But the announcement of a resin machine is a bit of surprise, given the company’s very long – almost ten years long – experience with the other 3D printing process. How has Prusa Research been able to catch up?

It turns out they simply acquired a fellow Czech company that had already produced a resin-based 3D printer, Futur3D. This company has been developing and marketing resin-based 3D printers for several years, even appearing once in our pages for their 3DWARF model.

That machine was DLP-based, meaning a tiny DLP chip reflected light through a lens to illuminate a liquid photopolymer resin surface. One issue with this approach is that the lens tends to stretch the pixels towards the edge of the print area, slightly distorting the prints, particularly larger-sized prints.

Is this what Prusa Research is getting into?

No, it turns out the new Prusa SL1 does not use the DLP process, but instead uses an LCD approach that avoids the distortion problem. The SL1 has a full LED lighting panel directly underneath the clear resin tank. In between the panel and the tank is a fine LCD screen, with pixel resolution of 2560 x 1440 pixels, each 0.047mm square. This is exact X-Y size of the solidified voxels on the SL1, as the LCD pixels match 1:1 with the voxels as they are built.

As for the Z resolution, the SL1’s Trinamic drivers allow for movement as little as 0.01mm, although the company is recommending using 0.02mm as a standard. Either way, that’s pretty fine.

The SL1 has an unusual calibration system: the build plate is mounted on a ball joint, which, as you might imagine, can move about and thus introduce situations where one side of the plate is slightly off the tank bottom, leading to poor quality prints.

To calibrate this, the SL1 simply drops the loose plate into the tank and lets it settle on the bottom, exactly matching the tank surface. Then the operator tightens the ball joint, leaving the plate in the perfect orientation.

The SL1 also includes a resin sensor that will alert the operator to pour in additional resin, should a print be so large that it is about to consume all the material available.

One controversial aspect of resin 3D printing is the sticking problem. In most systems, including the SL1, the light source flows upwards through the bottom of a clear resin tank. This light energy causes the liquid photopolymer to selectively solidify. That’s what you want to happen, but a side effect is that this fresh layer is also slight fused to the bottom of the tank, necessitating special action.

Some machines perform a “peel process”, where the plate is tipped slightly to peel the sticky print layer off the bottom of the tank, and permit fresh resin to flow inwards for the next layer build.

Other more advanced machines use specialty tank surfaces to limit adhesion, or, in the case of Carbon, use a chemical process to eliminate sticking altogether. What does the SL1 use?

The company explains they’re using something called FEP, which is a transparent Teflon-family film commonly used by other 3D printers to reduce adhesion. While it does not eliminate adhesion, it reduces it sufficiently to allow for layer durations of only six seconds. The SL1 will take exactly six seconds to print each and every layer regardless of the model size. While FEP isn’t the best coating, it is easily replaceable at low cost. This can be done in the same tank so you need only replace the tank.

Prusa Research believes the SL1 will be successful because they will apply the same formula to the machine. Josef Prusa explains:

“Original Prusa i3 MK3 was a major step forward in terms of reliability and ease of use thanks to its many sensors and smart features. I actually said that MK3 is ‘bloody smart’. And SL1 will be no different. You can expect smart features, safety mechanisms, detailed manuals and handbooks, 24/7 live support, perfectly described functions, easy maintenance and cheap spare parts… things that are usually not found in cheap Chinese 3D printers.”

The company is also developing a combination print washer / curing station as an accessory for the SL1. Having used several very messy resin machines, I think this could be a big seller.

Prusa Research offers pre-orders for the machine right now in a couple of configurations:

• SL1 Pre-assembled: US$1,599 (Ships December)

• SL1 DIY kit: US$1,299 (Ships November)

• Washer / Cure Station: US$699

• Washer / Cure Station with printer: US$200 Discount

I’ll have more thoughts on this development in a future post.

Via Prusa Printers