I've written in the past about my Robo R2 and how happy I am with it, and how the only reason I bought a Prusa i3 Mk3 as well was because if anything went wrong with the Robo, I didn't want to regret not buying my first choice for a 3D printer.
With that being said, the Robo has been an absolute rock star since I bought it. I'm so happy with it, and it has never let me down, save for one issue it has more regularly than I like. Prints kept welding to the print surface to the point where if anything hand any kind of surface area on the bottom, I wouldn't even attempt it on the R2. Meanwhile, over on the Prusa, the included smooth PEI sheet was a hero. You flex, the print pops off, you go on with your day. It's an utter miracle. How could this not be available for the Robo? Not fair!
Then I found out that Robo did have a removable flex plate system and their system is made by Buildtak, the company that makes the print surface, so I bought the Buildtak one (since the actual one branded by Robo was not available at the time). I got the kit, set it up, calibrated the printer, did a test, boom. Print welded. Flexed, print still welded. In fact, I had to attack the print with a scraper to get it off the bed. To say I was annoyed is more than an understatement.
So I took the Buildtak off the piece of steel, put a new sheet on, and tried again. Print welded.
Shaking in anger, I flung it at the wall and went to bed.
The next morning I woke up with an idea: what if I tried printing on the steel? Sure you can print on glass, so why not steel? I spread some Magigoo on, did a print and it worked! Okay cool! But then the next day came and I tried it again and it did not work at all. No adhesion.
Frustrated, I basically gave up and client work was done on my Prusa for a bit.
A few weeks earlier I had ordered a powder-coated PEI sheet from a seller on Amazon that was a knockoff of the Prusa one that's never available. It's well-made and coated just like the Prusa one, but it's actually available.
Then it hit me. What would stop me from trying the powder coated sheet in the Robo, since I've already put the magnets on the bed anyway? I learned the answer very quickly:
After some fiddling, I figured out how to get the larger sheet into the Robo and have it avoid the door hardware as the bed moved up and down and I did a test print. It was amazing. When the print stopped, I reached in to grab the print and it came off in my hand. I immediately went back to the same manufacturer and ordered an 8x8 one to fit the Robo. The combination of the magnetic base from Buildtak and the powder-coated PEI sheet have turned a printer that I loved into a perfect printer. Over the past 3 days I did a 45 hour print that adhered for the entire time and released with ease when it was done.
So now for the takeaways. Here's how you do it.
1. Buy the Buildtak Flexplate system. It's readily available for a lot of different printers.
2. Buy the powder-coated PEI sheet from this seller (that's the one I used, I can't vouch for others).
3, Adjust your Z-offset and enjoy the greatest thing you'll ever do to make your 3D printer better, just don't forget to clean it with alcohol regularly (or even after every use).
This is the kind of upgrade that's a bit spendy (about $120 in materials) but that I wouldn't go back to not having. In fact, going forward, if I can't get a powder-coated PEI sheet for a printer, I won't buy that printer.