What Was Happening
A customer in Putney SW15 had recently purchased and assembled an Anycubic Kobra 2 as their first 3D printer. The assembly had gone smoothly and the printer moved correctly, but every print came out looking wrong. The walls were thin and weak — the customer described them as “see-through” in places. There was also heavy stringing between separate features on the model, leaving fine threads of plastic draped across every gap.
The customer had been trying to fix the problem for a week. They had adjusted temperatures, tried different filament brands, tightened belts, and relevelled the bed — all without improvement. The printer had been working this way since its very first print, which initially made the customer suspect a hardware defect. They contacted us to determine whether the printer was faulty or whether something else was wrong.
Our Diagnosis
Since the problem had been present from the first print, we started by checking the slicer configuration rather than the hardware. The customer was using Cura and had loaded a profile downloaded from a 3D printing forum, described as “optimised for the Kobra 2.”
The first thing we noticed was the nozzle diameter setting. The profile was configured for a 0.6 mm nozzle, but the Kobra 2 ships with a 0.4 mm nozzle as standard. This single error accounted for most of the under-extrusion. With the slicer set to 0.6 mm, the toolpath was spaced for a wider extrusion width than the 0.4 mm nozzle could produce. The result was lines that didn’t overlap properly, creating the thin, weak walls the customer was seeing.
We also checked the nozzle temperature. The profile had PLA set to 220°C — approximately 20°C higher than the optimal range for most PLA brands. At 220°C, PLA becomes extremely fluid, which increases oozing from the nozzle during travel moves and produces the heavy stringing the customer described. The combination of over-temperature and incorrect nozzle diameter explained both symptoms perfectly.
The retraction settings in the downloaded profile were also wrong for this printer. The Kobra 2 uses a direct drive extruder, but the retraction distance was set to 5 mm — a value more appropriate for a Bowden tube printer. On a direct drive system, 5 mm of retraction can pull filament too far back into the heat break.
The hardware itself was in good condition. Belt tension was correct, the frame was square, the bed was level, and the nozzle showed no signs of clogging. This was purely a software configuration issue.
How We Fixed It
We started by creating a clean Cura profile for the Kobra 2 with the correct nozzle diameter of 0.4 mm. This immediately corrected the extrusion width calculations, bringing the toolpath spacing in line with what the nozzle could actually produce.
Next, we reduced the PLA nozzle temperature from 220°C to 200°C. We arrived at this value by printing a temperature tower — a calibration model that prints a section at each temperature from 190°C to 220°C in 5°C increments. The 200°C section showed the best balance of layer adhesion, surface finish, and minimal stringing for the customer’s PLA brand.
We then tuned the retraction settings for the Kobra 2’s direct drive extruder. We reduced the retraction distance from 5 mm to 0.8 mm and set the retraction speed to 45 mm/s. A retraction test tower confirmed that 0.8 mm eliminated visible stringing between the test pillars.
The flow rate also needed adjustment. With the nozzle profile now correct, we printed a single-wall calibration cube and measured the wall thickness with digital callipers. The measured wall was slightly thicker than the slicer’s target, so we reduced the flow rate from 100% to 95%, which brought the actual extrusion in line with the calculated value.
Finally, we printed a full calibration cube — a 20 mm × 20 mm × 20 mm model used to verify dimensional accuracy. The finished cube measured within ±0.1 mm on all axes, with clean, solid walls and no stringing. We saved the calibrated profile to the customer’s Cura installation and walked them through the key settings so they would understand what to adjust if they switched to a different filament in future.
The Result
The difference was immediately visible. The customer’s first print after calibration — the same model that had previously come out thin and stringy — printed with clean, opaque walls, no stringing, and accurate dimensions. Wall thickness was consistent throughout, with no visible gaps or translucency. The customer printed several test models whilst we were still onsite, all of which came out correctly. The entire diagnosis and calibration took approximately 1.5 hours.
They left with a saved profile they could reuse, which meant future prints started from a known-good baseline instead of trial and error.
Why This Happens
Slicer configuration is the most common source of print quality problems on new 3D printers, and it’s the one most beginners overlook. The physical assembly of a modern printer like the Kobra 2 is straightforward, but the slicer — the software that converts 3D models into printer instructions — has dozens of settings that must match the specific hardware. The nozzle diameter, in particular, is a foundational setting that affects every other calculation the slicer makes: line width, layer spacing, flow rate, and retraction behaviour all depend on it being correct.
Forum profiles are a common trap for new users. Someone shares a profile that works well on their printer, and others download it assuming it will work on theirs. But subtle differences — a different nozzle diameter, a different filament brand, a slightly different hotend assembly — mean the profile rarely works without adjustment. The Kobra 2’s default 0.4 mm nozzle is standard, but 0.6 mm profiles are common in the community because some users upgrade to larger nozzles for faster printing. A new user downloading one of these profiles has no way of knowing it was created for different hardware.
Temperature is similarly profile-dependent. PLA brands vary in their recommended temperature range by 10–20°C. A profile set for one brand at 220°C will over-heat a different brand that prints best at 200°C, causing excessive stringing that no amount of retraction tuning will fully eliminate.
Local Help in Putney SW15
We’re based in Putney SW15 and provide 3D printer setup and calibration for customers across the area. New printer setup is one of the most common jobs we handle — getting the slicer configured correctly from the start saves weeks of frustration and wasted filament. We work with Anycubic, Creality, Prusa, Bambu Lab, and most other consumer FDM printers.
If needed, we can also create and test material-specific profiles for PLA, PETG, and TPU so you are not recalibrating from scratch each time.
Prevention Tips
- Always verify the nozzle diameter in your slicer matches the physical nozzle on your printer. This should be the first thing you check when setting up a new slicer profile or downloading one from the internet. It’s the single most impactful setting in the entire slicer.
- Print a temperature tower before committing to a temperature for a new filament. Every PLA brand has a different sweet spot. A five-minute calibration print saves hours of stringing troubleshooting.
- Be cautious with community slicer profiles. If you download a profile, check the nozzle diameter, retraction type (Bowden vs direct drive), and temperature values before printing. Don’t assume it matches your hardware.
- Print a calibration cube after any slicer change. A 20 mm cube takes 15 minutes and immediately reveals whether your dimensional accuracy and extrusion are correct.
- Keep your slicer updated. New slicer versions often include updated default profiles for popular printers that are more accurate than community-created ones.