A few brief notes on printing with Polycarbonate on a Prusa MK3S.

Most consumer PC filaments require nozzle temperatures higher than regular printers can handle. The fancier PC filaments can require 320C nozzle temps or higher. Problem is, without a few upgrades, most printers can’t handle >=300C print temperatures. Thankfully, Prusa sells “Prusament PC Blend” which prints at 275C.

Perhaps not surprisingly, slicing with PrusaSlicer, printing on a Prusa printer, and using Prusament filament, all comes together really well. The biggest problem is bed adhesion. PC prints really want to warp and pop off the build plate, even with the bed at 110C. I’ve made a couple tweaks to Prusa’s recommended setup and have no bed adhesion issues now, even with large prints.

• Use a >= 5mm brim. I typically hate brims because they never come off cleanly so there’s always extra post-processing. In this case, a brim is necessary as it helps hold down the part.
• Use the textured steel bed plate. I didn’t have much luck on the smooth plate. The trick with the textured plate is that you can smoosh the first layer down into the ridges to get better adhesion. It also provides a place for the adhesive to stick without impacting the first layer.
• Use Magigoo. Prusa recommends PVA glue and provides a stick with every spool of Prusament PC. I didn’t have much luck with it, honestly. Glue is better than nothing but I still had adhesion issues on all but the smallest prints. Magigoo, on the other hand, has worked perfectly every time and is easier to apply and clean up. I use Magigoo for everything else and I was glad to discover they offer a solution specifically for PC. The important part is to be patient when cooling the print. Let it cool for long enough and the Magigoo will “release” and the part will literally pop right off the plate.

So, the summary:

• Prusament PC blend on a Prusa MK3S, sliced with PrusaSlicer
• 5mm brim
• Magigoo bed adhesive

Warning

If you print with PC a lot, you might want to check your fan shroud. Prusa prints fan shrouds with ASA which starts to deform around 80C. I spent a week or so doing nothing but PC prints and came to realize that my fan shroud was drooping. It was almost scraping the prints. When I got it out of the hotend, I realized that the whole thing was deformed and obviously starting to melt. So, the air around the hotend must be getting pretty damn warm.

Luckily for you, it’s possible to reprint the fan shroud using models provided by Prusa themselves. PC parts might start to deform a bit around 93C or so and shouldn’t melt much at all until 110C. If the air around your hotend is getting over the boiling point, the printer is probably on fire. I reprinted mine at .15mm layers and all has been well since.