Prusa SL1 SLA 3D printer build and first impressions

 I ordered this printer almost a year ago, but then the MINI appeared and I decided to get a MINI too, so my new order was delayed due to the MINI massive backlog. It was delivered last March, just at the beginning of the pandemic, so I thought I would have plenty of time to devote to it. But I was wrong and it has been sitting inside the box in our home's hall for several months. 

To be honest, I knew the resin will be smelly so I was not eager to build this printer unless I had a use for it. That and the almost unavailable Isopropilic Alcohol (IPA) that was needed kept the project on hold. But given I finally got a good deal for IPA on Amazon something needed to be done.

So last Saturday morning I started unpacking the several layers of foam with parts and went ahead building the Prusa SL1 printer. I would say it was simpler than the MK3, with lots of folded metal and machined aluminum parts and just a few 3D printed parts. Lots of screws and a good number of active parts and electronics. All in all, a fun build that took me around 4 hours. 

Most of the calibration done afterward was automatic so I just needed to sit there and watch. So the next logical step was to print something and for that, I tried to get my wife involved. So we looked on Thingiverse for some nice earring that she liked and I loaded it onto PrusaSlicer software. 

The SL1 printer has a USB port that you can use, similar to the MINI, to bring a file from the computer to be printed. But the SL1 comes with both Wifi and Ethernet network connections. I managed to configure the wifi but despite the external antenna it got a poor signal in this room, so wifi turned useless. I took the Ethernet cable out of the MINI sitting next to the SL1 and plug it into the latter. Then, I went on to search for it within PrusaSlicer software and the printer IP address was found. But when pressing the "Test" button I was told the API key or password was wrong.

I was not aware of any password or API key, so I went to the manual looking for help but I found nothing about it. But I noticed a menu entry on the printer about "Login info", where a username (maker) and password (*******) were provided. I placed that password in the password box on PrusaSliced and, voilá, the connection test was now successful. The printer was now happy to talk to PrusaSlicer. So I assumed I could just send the print job directly through the network (without the use of the USB Pendrive). And I was right, it worked nicely and fast. I could see the upload progress on the SL1 display.

However, the upload process does not lead to starting the print. So after a few seconds, I went to the home menu, selected print, and now I could see my project in the list of available files ready to be printed. I went ahead and a few hours later my project was printed. 

But it was not all so easy, at the beginning of the print I could hear a release noise every time a layer was printed. It was the noise of the last layer detaching from the FEP film every time the resin vat was tilted before the print platform was pulled up to the next layer. But after a few layers, I no longer could hear any noise. That led me to think that maybe the parts detached from the print platform and remained attached to the FEP film. I suspected my first print would end up in a failed print and I was feeling guilty for not doing one of the sample objects as a first print job, as recommended. 

You know, the problem with this printer is that firmware does not allow you (now) to pause a print and raise the print platform so you can visually check whether the part is properly stuck to it or to the vat bottom (which is one common fail mode). It appears that feature was present in older versions but it was removed later, as it created a mark on the current layer (I guess due to backslash in the Z-axis motion system). 

Luckily, after around one hour and a half, the print platform could be seen and it was obvious the print was working nicely. Some of the printed parts, now halfway, were hanging in there as they should.  But when the print was over I did not want to take care of the mess of cleaning up so I left all inside the printer till the next day. 

I bought the Prusa CW1 washing and curing station together with the SL1 printer as a bundle, as I was well aware of the mess SLA postprocessing is. But the CW1, contrary to the SL1, is not sold as a kit but it is a ready-made unit that works out of the box. With it, you can make the post-processing a bit less messy and more convenient. Still, the smell of the resing and the need of using gloves and wipes is guaranteed. And while I am printing something with the SL1 as I write this entry on the same table, I know I cannot do that often, as the smell is very noticeable and unpleasant. 

My first 3D printed parts with the SL1 came out ok but not perfect. I printed them at 35 microns. The resolution is good but one of the parts is slightly bent. Supports removal was easy but it left some tiny wounds on the object's surface. 

Conclusion

I think the SL1 is a polished product, with a nice touch-sensitive UI and good networking capabilities. As an SLA printer it seems quite ok, but I am afraid I am not yet a fan of the SLA process. I find FDM, while lower resolution, better in almost any other way (and also cheaper). 

All that said, I am aware that there are a lot of other SLA printers that are way cheaper than the Prusa SL1. And while they do not share all its features, I know many users are happy with them. Anycubic Photon is perhaps the one that I know more owners of, most of them happy. 

I have to be using the SL1 longer to make a more elaborate impression about this printer. I would say it is the most sophisticated printer on Prusa Research products so far and I love the display and its responsiveness. Way better than the MINI, which way better thab the MK3's. 

And while the SL1 has the smaller footprint of all Prusa printers, the advantage is lost if you add in the CW1 unit. Still they look cool next to each other.