How to 3D print polycarbonate (PC) filament

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Here is how to 3D print polycarbonate (PC), one of the strongest and most heat-resistant filaments you can 3D print at home.

For a long time it sat in a box, waiting for its time to shine. However, despite years of 3D printing under my belt and mastery of PLA, PETG and even rubbery TPU, that time never came.

Until, that is, my first Fiverr 3D print gig. With the customer specifically requesting polycarbonate (PC for short), it was time to unbox the Prusament Jet Black PC Blend I bought alongside my Prusa MK3S+. How difficult could 3D printing one of the toughest filaments around really be?

Initially, challenging was an understatement. Even with the print bed at 110°C and the 0.4mm nozzle at 275°C, absolutely nothing wanted to stick on the smooth sheet. A 5mm brim, skirt and the Prusa PC printing profile did nothing to help with adhesion.

This was odd because I had been lead to believe that PC could pull away the top layer of the print bed if not careful. My reality was that you would get a few layers before an edge warped and the nozzle ended up pushing it around.

So I swapped to the Prusa textured sheet. Glue, no glue, bed to 120°C, nozzle temperature to 285°C to account for the steel nozzle – it all should have helped. Sadly, the print still went for a walk a few layers in.

What was usually fine for PETG just did not work. So, as the 3D printing joke goes, I messed with the Live-Z. I squished the filament to way beyond the usual level. Too much, in fact, based on a 100x100mm calibration square, so I dialled it back for a gloriously flat and smooth first layer.

This time, things stuck. Not so much I needed to use a layer of gluestick, with prints easily popping off once cold. It was enough that I did not need to use some 3DLac I bought to save the day. With a deadline looming, relief was an understatement.

It was the same story with the smooth PEI sheet. Once the Live-Z is dialled in, prints stick happily though I would advise a layer of gluestick to help protect the surface.

From here on out, the jet black Prusament PC Blend played ball. Even after 12 hours of drying at 60-70°C, I did still notice a few air bubbles caused by some residual moisture. Polycarbonate is highly hydroscopic, after all, though the Prusa blend is much less prone to it.

Apart from that, it came out neater than I expected and was consistent. Not quite PLA smooth, with some minor stringing, but still. More importantly, it was strong. Where I can usually break PLA and PETG with my bare hands, polycarbonate laughed off the challenge.

Except, that is, the supports, which (much to my surprise) were super easy to remove. More so than other filaments I have used. They did not even really leave any scarring.

No wonder PC is used in high-strength applications such as automotive. Knowing what I do now, I was wise to order it alongside my 3D printer. But totally unwise to leave it so long without giving it a go. It really is a beast of a filament for functional parts.

Why use polycarbonate (PC) filament?

If you want to maximise prettiness, PLA is the better option. Polycarbonate and its carbon fibre variant is built to be strong. To survive where other filaments would fail. PLA starts to get soft at 60°C while PETG is not much better.

Polycarbonate in Prusament PC Blend form, by comparison, can stay in shape up to 113°C. A modest claim by Prusa, while other filaments may do even better at the expense of printing fussiness. PC is also impact resistant and even has electrical insulating properties.

What it does best, however, is survive. In various tests, including one by CNCKitchen, PC came out top in various strength categories, beating ABS and PETG.

Just make sure you use a skirt or, even better, an enclosure as drafts can and probably will warp larger prints (some people use magnets at the corners to help). Now for some pointers that made printing with PC successful for me.

Prusament PC Blend printing pointers

• Nozzle temperature: 265-285°C (275 with steel nozzle is great)
• Bed temperature: 120°C (115°C is sufficient)
• I found 275°C and 120°C worked best in my enclosure
• Use a 5mm brim at minimum
• At least a few layers of skirt can help with drafts
• Dry the filament before printing (8 to 12 hours)
• Squish the filament (low Live-Z)
• A textured or satin sheet is preferable to avoid damage
• Consider a glue layer to protect the bed surface regardless of sheet type
• Print slowly to ensure stronger layer adhesion (40mm/s)
• Use an enclosure to reduce warping from drafts
• Fan speed should be 20% at maximum (30% for bridging) but consider 0% for first layer
• The Prusament PC Blend default is reliable but can be too fast (hello warping)
• Try to reduce the extrusion to 0.97 (97 per cent) if you get blobbing
• Prints that get pushed off the bed can also be a sign of a too low Z-level
• 25-40% works well for infill (I like honeycomb, personally)
• Magents can be used for large prints but be mindful when using a steel nozzle
• Too many perimeters can increase chance of warping and is not necessarily needed