PETG Starting Settings for the Original Prusa MK4
The values on this page are Prusa’s material starting guidance for the MK4 family, not a controlled print result for every PETG product. Treat them as a conservative place to begin after recording the exact product, colour, nozzle, sheet, firmware, and PrusaSlicer release.
Record the setup first
Before slicing, write down the MK4 variant, nozzle diameter and material, firmware, PrusaSlicer release, PETG brand and product, spool dry history, selected sheet, and desired result. PETG can change with formulation, colour, moisture, surface, and nozzle wear. A profile name alone is not enough to reproduce the print.
The MK4 family uses a load cell to check nozzle proximity to the steel sheet during mesh bed leveling. That automatic check is not an adhesion or print-quality test. After a nozzle or sheet change, and whenever the first layer looks wrong, inspect the hardware, run the relevant self-test, and verify the first layer on the actual sheet.
Starting values from Prusa guidance
| Field | Starting point | Boundary |
|---|---|---|
| Nozzle, first layer | 230 °C | Prusa material guidance; not an MK4/product measurement. |
| Nozzle, later layers | 240 °C | Confirm the selected product’s instructions and current profile. |
| Bed, first layer | 85 °C | Material guidance; surface condition still controls adhesion. |
| Bed, later layers | 90 °C | Use the selected sheet’s profile and verify that the result is not deforming. |
| Sheet | Powder-coated TXT or satin are the documented preferences | Smooth PEI may bond too strongly and can be damaged; do not generalize that warning to every third-party sheet. |
| Speed and volumetric limit | Start with the selected MK4/PETG profile and inspect preview flow | Prusa describes maximum volumetric speed as a limiter, not a speed booster. No MK4/product limit was measured here. |
| Cooling and retraction | Use the product/profile starting values, then test for stringing and bridges | PETG trade-offs depend on product, geometry, airflow, and desired toughness. |
For a named product, its own data sheet takes precedence over a generic material table. For example, PolyLite PETG gives product-specific values of 230–240 °C nozzle, 70–80 °C bed, 30–50 mm/s nozzle speed, and 70 °C for 8 hours drying. Those figures are not an MK4 test and must not be silently merged with Prusa’s PETG values.
Prusa’s drying table lists PETG at 55 °C for 6 hours as a Prusa/Prusament starting instruction. Check the chosen filament maker’s recommendation and spool construction before heating a spool; do not treat one drying schedule as universal.
Validate in stages
- Clean and correctly seat the selected sheet. Confirm the nozzle, sheet, material, and layer-height profile in PrusaSlicer before exporting G-code.
- Print a small first-layer pattern. Look for gaps, excessive squish, lifting, or a bond that is too strong. A successful load-cell check does not answer those questions.
- Use a temperature tower or similarly controlled comparison if the product window is uncertain. Judge stringing, layer adhesion, overhangs, bridges, and surface finish for the intended part. A tower result is comparative, not a universal optimum.
- Inspect preview flow and keep maximum volumetric speed conservative. PrusaSlicer resolves the lower non-zero print or filament limit; increase it only when the actual product, hotend, and print support that change.
- Run a small functional part, then save the resolved profile together with the PETG product, sheet, dry state, nozzle, firmware, slicer release, and observed result.
If stringing persists, do not jump straight to a large retraction change. Recheck moisture, nozzle cleanliness and installation, temperature, sheet context, and the chosen test result one at a time.