Longer LK4 X

The Longer LK4 X is an FDM 3D printer from Longer with a 220 x 220 x 250 mm build volume.

Specifications

The Longer LK4 X represents the modern generation of Longer's product line, integrating current hardware standards to compete with contemporary desktop FDM (Fused Deposition Modeling) printers. This model is a major upgrade over the older Pro series, transitioning from Bowden-style extrusion to direct-drive feeding, and introducing automatic bed leveling.

• Hotend (Hotend): The most significant hardware update in the LK4 X is the Direct Drive Dual-Gear Extruder. The drive motor is mounted directly on the print carriage, reducing the filament path to the melt zone to just a few millimeters.

Calibration

Tuning the Direct Drive extruder and Auto Bed Leveling on the Longer LK4 X requires specific adjustments. Follow these 8 steps:

• PEI Build Surface Cleaning:

The PEI coating can lose adhesion due to finger oils. Clean the build surface with isopropyl alcohol (IPA) using a lint-free cloth before starting a print.

• Expected result: A clean surface with strong first-layer adhesion.

Common defects

• Hardware defects and mechanical weaknesses
• Heat Creep at Slow Speeds:
• Symptoms: The print starts normally, but after 30-40 minutes the extruder stops feeding, and filament swells and jams above the heater block.
• Cause: The stock hotend cooling fan fails to dissipate heat effectively from the heatsink, allowing heat to rise up the throat.
• Solution: Verify the cooling fan is running at maximum speed.

What it is used for

Best use-cases:

• Flexible Filament (TPU) Printing: The dual-gear direct drive extruder handles gaskets, phone cases, and soft components reliably.
• Rapid Prototyping: The PEI steel bed and ABL sensor reduce setup times between prints.
• PLA and PETG Parts: Offers good interlayer bonding and clean extrusion control due to the geared extruder.