Printing with the Prusa Pro HT90: Settings, Materials, and Practical Tips

Eolas Prints

Jun 9, 2026

Engineering Materials High Temperature 3D Printing PEEK Print Settings Prusa Pro HT90

Prusa Pro HT90 printing in progress — settings and materials guide

You've decided the HT90 is the right machine. This guide covers what you actually need to know to get reliable results: how to set up the machine, which head to use for which materials, settings per material class, bed adhesion, and the most common issues you'll encounter when printing high-performance polymers.

First: Chamber Preheating

For engineering and high-performance materials, chamber preheating is not optional — it is the first step in every print. Start heating the chamber before loading filament and before starting the print job. For PEEK and similar materials, allow the chamber to reach full temperature (90°C) and stabilise for at least 15–20 minutes before printing begins. Printing before the chamber is fully stabilised is one of the most common causes of first-layer delamination and warping in high-performance materials.

For standard materials (PLA, PETG), the chamber can remain open or be heated to a lower temperature. There is no requirement to use the full 90°C for materials that don't need it.

Head Selection

The HT90 ships with two heads. Choosing the right one before printing is important — both are optimised for different conditions.

Head	Best for	Max nozzle temp
High-Flow Head	PLA, PETG, ABS, ASA, PA — standard and engineering materials up to ~300°C	~300°C
High-Temperature Head	PEEK, PEKK, PPS, PSU, PEI (Ultem) — all materials requiring >300°C nozzle	500°C

Swapping heads takes a few minutes without tools. The load cell sensor recalibrates the first layer automatically after each swap — no manual intervention needed.

Settings by Material Class

Standard Materials (PLA, PETG)

Nozzle temperature	PLA: 200–220°C / PETG: 230–245°C
Bed temperature	PLA: 50–60°C / PETG: 70–85°C
Chamber	Not required — can print with chamber open
Print speed	Up to 200–300 mm/s with Input Shaper enabled (PLA)
Head	High-Flow

The HT90 with Input Shaper is extremely fast with standard materials. Use it for high-volume prototyping in PLA or PETG and you'll see throughput that rivals dedicated high-speed machines.

Engineering Materials (ABS, ASA, PA, PA-CF, PCCF)

Nozzle temperature	ABS/ASA: 240–260°C / PA-CF: 260–290°C
Bed temperature	ABS/ASA: 100–110°C / PA-CF: 80–100°C
Chamber temperature	50–80°C recommended
Cooling fan	Minimal or off for ABS/ASA; low (10–20%) for PA-CF
Print speed	40–80 mm/s
Head	High-Flow (ABS/ASA) or High-Temperature (PA-CF with abrasive fill)

ABS and ASA benefit substantially from the heated chamber even at 50–60°C. Warping disappears almost entirely. For PA-CF, ensure the filament is fully dry before printing — PA absorbs moisture aggressively and wet PA-CF prints will be brittle regardless of settings.

High-Performance Materials (PEEK, PEKK, PPS, Ultem)

Nozzle temperature	PEEK: 370–400°C / PEKK: 340–380°C / PPS: 310–350°C / Ultem: 360–420°C
Bed temperature	120–160°C (material dependent)
Chamber temperature	80–90°C — must be fully stabilised before printing starts
Cooling fan	Off or minimal — semi-crystalline polymers need controlled cooling, not rapid cooling
Print speed	20–50 mm/s — slower than engineering materials
Head	High-Temperature (required)
Infill	40–80% for functional parts; rectilinear or gyroid
Wall count	4–6 perimeters for structural parts

Bed Surfaces for High-Temperature Materials

Standard PEI surfaces are not ideal for PEEK and Ultem — adhesion can be inconsistent and removal difficult. The most reliable options:

Garolite (G10/FR4): The gold standard for PEEK adhesion. Parts adhere well at temperature and release cleanly when cooled. Surface must be lightly sanded between prints to refresh adhesion.
PEI with PEEK adhesion promoter: A high-temperature adhesion compound applied before printing. More consistent than bare PEI for PEEK.
Borosilicate glass with PVA or PEEK adhesive: Works reliably but requires more preparation time per print.

Do not use standard glue stick for PEEK prints — it will not survive the bed temperatures involved. Standard PLA/PETG adhesion solutions do not apply here.

Drying — The Step Most People Skip

Engineering polymer moisture absorption is not a minor issue — it is the single most common cause of print failures and substandard mechanical properties. Hydrolysis at printing temperatures permanently degrades polymer chains. Parts printed with wet PEEK or PA-CF will be brittle, regardless of how good the settings are.

PEEK / PEKK / Ultem / PPS: Dry at 120°C for 4–6 hours minimum. Use a dedicated oven, not a standard filament dryer — 50–70°C is insufficient.
PA-CF / PA-GF: Dry at 80–90°C for 6–12 hours. Feed from a sealed dry box during printing where possible.
After drying, store in sealed containers with fresh desiccant. Do not leave spools of engineering materials on the printer between sessions.

Annealing Finished Parts

PEEK parts can be annealed after printing to further improve crystallinity and mechanical properties. Place finished parts in an oven at 150–180°C for 1–2 hours, then cool slowly (in the oven with the door closed). This increases crystallinity from the as-printed ~20–25% to 30–35%+, improving stiffness, chemical resistance, and dimensional stability. Allow 1–2% dimensional shrinkage during annealing — compensate at design stage for precision parts.

Common Issues and Fixes

First layer not adhering (PEEK)

Almost always caused by insufficient bed temperature, insufficient chamber preheating time, or the wrong bed surface. Check that the chamber has been at 90°C for at least 15 minutes, bed is at the correct temperature for your surface, and that you're using garolite or an appropriate adhesion promoter. Clean the bed surface with IPA before printing.

Delamination between layers

Cooling too fast — either the chamber temperature is too low, the cooling fan is running at too high a percentage, or the print speed is too fast (too much time between layer depositions allows layers to cool). Reduce fan to zero for PEEK. Slow down print speed. Ensure chamber is fully stabilised before starting.

Warping or lifting corners

Thermal gradient too high — the part is cooling unevenly. Increase chamber temperature if not already at 90°C. Use a brim (5–8mm) for large flat parts. Ensure bed temperature is correct for your surface.

Brittle parts despite correct settings

Wet filament. Dry at the correct temperature (120°C for PEEK) for the full recommended time and reprint. This is nearly always the cause.

Nozzle clogging

Usually caused by incorrect temperature (too low for the material — under-melting), retraction that's too aggressive (pulling semi-crystalline material back into the cold zone), or contamination. Perform a cold pull with the High-Temperature head at ~250°C to clear. For PEEK, a purge with a lower-temperature material (PETG or ABS) can help clear residue.

Slicers and Profiles

PrusaSlicer has official profiles for the HT90 and is the recommended starting point. Bambu Studio and OrcaSlicer can also be configured for the HT90 but require manual profile creation. For PEEK and other high-performance polymers, start from Prusa's official profiles and adjust gradually — these materials are less forgiving than standard filaments and chasing settings changes one at a time makes it much easier to identify what is and isn't working.