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 my Prusament PC Blend sat in its box. Despite years of 3D printing under my belt and mastery of PLA, PETG and even rubbery TPU, I had been put off by horror stories of warping and adhesion issues.

Until, that is, my first Fiverr 3D print gig. With the customer specifically requesting polycarbonate (PC for short), it was time to unbox the 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. Sometimes even bend it. My reality was that you would get a few layers before an edge warped and the nozzle ended up pushing a blob 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 as it is called in Prusa land. 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 though that I needed to use a layer of gluestick, with prints easily popping off once cold. I did not even need to use some 3DLac I bought to save the day. With the 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 hygroscopic, 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.

It has great impact resistance too, which is why it is used for bulletproof glass. In its purest clear form or coloured, it can have a level of flexibility (like PET-G). This is why it is particularly good for automotive applications.

Where it fall down is that it is not especially UV resistant so you may see some colour discolouration if used outside. It is also a nightmare to print until you get used to its fussy ways.

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. A thicker, taller and highly squished first layer is a wise idea.

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
• Dry the filament before printing at 60-70°C (8 to 12 hours)
• Squish the filament (low Live-Z)
• A textured or satin sheet is preferable to avoid damage
• Consider a gluestick layer to protect the bed surface regardless of sheet type
• Print slowly to ensure stronger layer adhesion (15-40mm/s)
• Use an enclosure and skirt 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
• 15-40% infill (I like honeycomb or gyroid, personally)
• Magnets 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, two is super strong

What about printing PC on the Creality K1?

Using the default smooth bed, polycarbonate can be printed but it can be finicky. Ensure the first layer is super slow (15mm/s) and start with two perimeters and 25% gyroid infill maximum. If you can make that work, add another perimeter and increase the infill for even greater strength. Remember that infill strength can actually decrease beyond a certain point.

Another essential tip is to use the Z Offset option (settings > expert > Z Offset). You may need to enable root mode (but not actually root). For the first layer, set to the lowest setting of 0.005mm. For layer two and beyond, 0.0010 or 0.0025 works well. Or stick to the default 0.0050.

I found IPA (99% proof) reduces bed adhesion in conjunction with 3DLac spray. As is usually the case, what works best is a mixture of warm water and dish soap then dry with something lint free such as a paper towel or clean microfibre. I did not use a gluestick or 3DLac – waiting until the print is fully cooled pops off without causing damage and the adhesion is excellent. Just be warned that you could damage your bed if not careful.

One issue with polycarbonate is that, certainly Prusament PC Blend and a few other brands I’ve seen, is that it requires a bed temperature of 105°C – sometimes more. The K1 is limited to 100°C when using its touchscreen. It can, however, manage up to 115°C if controlling via Klipper (how to root guide here).

When I say 115°C, I mean you will get an error and printing stops if you even reach that maximum for a millisecond. Perhaps a change to a configuration file could get round this or perhaps it is a hardware maximum. Either way, stick to 113°C to ensure no hiccups as the bed fluctuates by around 0.5°C. If you do get the error, fortunately, prints can be resumed.

As for the K1 enclosure temperature, polycarbonate prefers consistency. With the nozzle at 275-285°C and the bed at 113°C, the enclosure stabilises around 48°C. Ample for Prusament PC Blend, but not so much you need to run the rear fan (and risk warping) to avoid overheating the K1 components. If using Klipper, set the maximum chamber temperature to at least 52°C just to be on the safe side, though this will depend on room temperature.

I also find that checking the print calibration function each print ensures consistency. This could, however, be coincidental. With polycarbonate, it is best not to take any chances.

Despite the enclosure, printing polycarbonate on the K1 can benefit from a skirt for most or all of the model.

As for cooling, I found 20-30% at most ensured great print quality without causing warping. The standard Prusa Prusament PC Blend profile in PrusaSlicer is perfect though for the nicest finish I slow the default print to 50-65%.

In addition, I ran the first ten layers without the extruder fan.

Polycarbonate (PC) is a scary filament to master and one I would not personally attempt without an enclosure and/or a draft-free environment. Enclosure temperature seems secondary to fluctuations and sudden cold spikes. So long as you get a good squished first layerGood luck!