Ultimate PETG Profile & Tuning Guide (PrusaSlicer / OrcaSlicer) - Ender 3, Neptune, Bambu & Bed-Slingers

🧵 PETG Print Profile — v4

After extensive testing and tuning, I’ve updated my PETG profile to v4. The goal of this profile is simple: PETG that prints almost as seamlessly as PLA while maintaining maximum mechanical strength.

This profile is primarily tuned for bed-slinger printers with Direct Drive extruders and 0.4mm nozzle.

⚙ Profile Highlights

• ⚙ Compatibility: Designed for PrusaSlicer 2.9.3 and above.

• ⚠ Material: This profile is optimized for standard PETG, not High-Speed PETG.

• Printer Type: Profile is for bed-slingers with direct-drive. ( Acceleration values are for printers with linear rods/rails which can handle up to 3000mm/s2) 👉 For full details about my Ender 3 Pro setup, visit my GitHub.

• Layer Height: The Arachne perimeter generator's Minimum Perimeter Width has been reduced from 85% → 40%. This allows finer details to print cleanly, with a practical lower limit of 0.16 mm layer height.

• Scarf Seam is configured in the profile but disabled by default. I recommend using it when appropriate, especially for circular parts where there is no travel in and out.

•  0.25 mm nozzle owners: Check the linked Prusa Forum thread.

🔁 Retraction & Z-Lift

PETG benefits significantly from proper retraction and Z-lift. These are the values used in my profile:

Lifting is a must for PETG. With Ramping Lift enabled, the lift movement is faster than normal Z-lifting.

• Maximum Ramping Lift: 0.3 mm

• Ramping Slope Angle: 12°

This results in approximately 1.44 mm of travel distance to achieve the 0.3 mm lift height.

I use: -0.02 mm deretraction extra length. This helps eliminate small gaps immediately following a seam by compensating for low nozzle pressure.However, this is printer-dependent, so your specific machine may not require this value.

🚀 Travel Speed & Acceleration

I set:

• Travel Speed: 300 mm/s

• Travel Acceleration: 3000 mm/s²

Higher travel speeds reduce the amount of time filament has to ooze during long travel moves. This can result in cleaner retraction towers, especially when testing long-distance moves.

If your machine is capable of handling higher values, you can increase them further.

👉 Test your retraction using the Full Retraction Test Model.

Use a retraction test model with towers at varying distances. With a properly tuned setup, you should be able to achieve zero stringing across all gaps.

🌡 Temperature & Cooling

PETG generally bonds best when printed hot with minimal cooling. Excessive cooling can reduce layer bonding and make the finished part more brittle.

The Consistent Surface cooling/speed logic keeps outer perimeter speed more stable, helping prevent VFA (Vertical Fine Artifact) visual artifacts.

See the linked Prusa Blog article about VFA Nerfing & Consistent Surface for more details.

🪡 Scarf Seam & Seam Settings

Scarf Seam is configured in the profile but disabled by default. I recommend using it when appropriate, especially for circular parts where there is no travel in and out, such as certain support geometries.

The configured settings are:

• Scarf Seam Placement — Everywhere: Applies smooth, ramped seam transitions across both outer and inner geometry.

• Scarf Seam Length — 2 mm: Kept short to prevent excessive PETG oozing/stringing during the slow ramp transition.

• Max Segment Length — 0.25 mm : Divides the 2 mm ramp into 8 micro-segments, providing maximum flow resolution.

• Scarf on Inner Perimeters — Enabled : Applies Scarf Seam transitions to inner perimeters as well.

• Scarf Only on Smooth — Enabled  : Sharp 90° corners revert to a standard seam to preserve crisp edges.

• Seam Gap Distance — 9 % : Relieves nozzle pressure immediately before seam closure.

• Staggered Inner Seams — Enabled: Shifts inner-wall seam points to avoid creating a vertical weak line and helps prevent internal bulging.

🧱 Infill Settings

• Only Retract When Crossing Perimeters: Disabled : This helps prevent nozzle buildup.

• Gyroid — 15%: Choose an infill pattern that minimizes unnecessary nozzle travel over the infill.

• Top/Bottom Pattern Both Concentric and Monotonic Lines work well for reducing nozzle buildup.

• Infill Anchor Length — 150% / 250% : These values help prevent the ghosting/hull-line effect.

🔩 Nozzle Recommendation

I strongly recommend using a hardened steel nozzle for PETG.

PETG sticks significantly less to hardened steel than to brass, resulting in:

• Cleaner outer walls

• Fewer stray blobs

• Less material sticking to the nozzle

🔥 Drying Your Filament

PETG must be dry for clean and consistent printing. Even a brand-new roll straight out of the box can contain enough moisture to affect print quality.

Dry PETG for 6–8 hours at 60–65 °C before printing. The easiest method is to use your heated bed together with a filament box.

👉 Check the linked video for a simple step-by-step drying method.

If you are running Klipper, simply set your bed temperature and increase the default timeout for the drying period.

Example:SET_IDLE_TIMEOUT TIMEOUT=21600

🎚 Extrusion Rate / Flow Rate

Correct flow rate is essential for achieving a smooth surface finish. With PETG, it is especially important because excessive flow can quickly cause nozzle buildup and surface blobs.

I use a two-step approach to dial in the flow rate.

🧱 Step 1 — Static Wall Test

1. Print a single-wall calibration cube using a 0.8 mm wall for a 0.4 mm nozzle.

2. In Print Settings → Advanced → Extrusion Width, set all extrusion widths to 0.4 mm.

3. Measure the printed wall thickness using a caliper.

4. Calculate the approximate flow rate.

Example

If the measured wall thickness is 0.83 mm:

0.80 / 0.83 = 96 %

So the estimated flow rate would be approximately:

96 %

This gives you a rough starting point.

In general, PETG flow rates typically end up somewhere between:

90 % – 100 %

💡 Seam measurement tip

Use the “Aligned” seam setting during this test. The wall section immediately after the seam may have a slightly different width than the rest of the wall. Do not include that section when taking your measurements.

⚙ Step 2 — Fine-Tune (Optional)

For a more precise result, I use OrcaSlicer's built-in calibration tool:

Calibration → Flow Rate → Pass 2

If you don't want to install OrcaSlicer, my experience is that the ideal flow rate for a smooth surface is usually approximately:

~2% lower than the static wall cube result.

⚖ Z Offset

Correctly setting the Z Offset is crucial when printing PETG.

A properly tuned Z Offset helps provide:

• Excellent first-layer adhesion

• Better surface quality

• Less material buildup on the nozzle

You can test your settings using the first-layer STL I shared for calibration.

🧩 Supports

Top/Bottom Contact Z Distance 0.24 mm

This is just slightly higher than the configured layer height, which is: 0.20 mmThe referenced video suggests 0.28 mm, while 0.24 mm has been working well for me.

👉 Watch the linked video for an explanation of why this setting works well for PETG supports.

⚙ Speed & Acceleration

Bed-slinger printers equipped with linear rails can handle 4000 mm/s² acceleration and above, depending on the machine. However, I prefer to stay in the safe zone for stability and print quality.

If your machine is capable of handling higher acceleration values reliably, feel free to increase them.

🧠 Linear Advance

To find the correct Linear Advance (K-factor) value, I prefer using the Ellis3DP Pressure Linear Advance Tool.

For PETG, my K-value typically falls between:

0.065 – 0.08

The exact value depends on the filament supplier. Keep in mind that the K-value is hotend-dependent, so your result may vary.

I left the shared profile at: 0.08

Location:  Filaments → Custom G-code

The included G-code is intended for Klipper.

💡 Important

Always run your Linear Advance test after dialing in your flow rate. Otherwise, the Linear Advance results will not be accurate.

📏 Shrinkage Calibration

Before calibrating shrinkage, first verify your X/Y e-steps.

1. Verify X/Y movement

Use a caliper fixed to the printer or guide rails. Printable mounts are available for this purpose.

Command the axis to move exactly:100 mmThen verify that the actual mechanical movement is exactly 100 mm.

🧭 Do not rely on measuring 3D-printed parts.

Mechanical measurement is far more accurate for verifying axis movement.

2. Calibrate PETG shrinkage

Once the X/Y movement has been verified, print a calibration cross (“calicross”) and check the resulting shrinkage. .Make sure this is done after adjusting the flow rate.

Typical PETG shrinkage: ~0.2 %

🌉 Bridging — Still Being Tested

I am still refining my PETG bridging settings, but these are the results I have found so far.

Excessive cooling can make PETG brittle, so I recommend combining:

• Moderate cooling

• Lower bridge speed

A linked test video demonstrates that using 150% flow during bridging can produce excellent results, with each extruded line bonding neatly to the previous one. (Second part of the video) 

The 150% flow suggestion is still being tested.

Current profile settings

💡 Bridging Flow note: 150% is the suggested value from the referenced test, but the current profile uses 0.97 and the 150% setting still requires more testing.

🧪 Quick Reference

For a quick starting point, the most important values are:

🏁 Final Notes

This profile is the result of extensive tuning specifically aimed at getting clean, strong and reliable PETG prints from a Direct Drive bed-slinger.

PETG is highly sensitive to:

• Moisture

• Flow rate

• Retraction

• Nozzle temperature

• Z Offset

• Travel behavior

• Cooling

So while these settings provide an excellent starting point, your exact filament, hotend and machine may require small adjustments.

If you achieve different or better results with these settings, feel free to share your findings so the profile can continue to improve.

Happy printing! 🧵🔥