The technology behind 3D printing continues to evolve, offering more precision and automation. Among these advancements, you might notice a curious behavior in some printers where the extruder heats up before the leveling process starts. While this might seem insignificant, this small step is critical in ensuring print quality and operational efficiency. This guide explores the reasons behind this process, its technical foundations, and tips to help you optimize and troubleshoot your 3D printer settings.
Why Does the Extruder Heat Up Before Leveling?
Importance of Pre-Leveling Heating
After leveling, heating the extruder ensures the printer operates in realistic conditions. Components such as the nozzle and bed can expand when heated, altering their dimensions. Preheating ensures calibration accounts for these changes, helping to prevent inaccuracies during the print process.
Consider this scenario: if the leveling process is done with cold components, the subsequent heating for printing might introduce thermal expansion that shifts the nozzle height or alignment. This can result in adhesion failure or uneven layers. Printers can achieve precision right from the first layer by heating the extruder and bed before leveling.
Optimizing Adhesion for the First Layer
The first layer is the foundation of any successful print. Adhesion issues such as warping, lifting, or detachment often stem from improper temperatures. A preheated extruder ensures that the first layer bonds adequately with the surface. When the printer levels are cold, the filament may not flow or adhere properly, leading to failed prints.
How Printer Firmware and G-code Manage Preheating
Firmware-Driven Precision
Like Marlin or Prusa, printer firmware manages hardware behavior during printing. These systems can schedule preheating before calibration to ensure consistent conditions. For instance, the firmware manages the thermistors that regulate bed and nozzle temperatures, guaranteeing accurate measurements during the leveling process. Advanced firmware can even modify heating profiles based on filament type, offering tailored precision.
G-code Commands in Action
Everything in 3D printing, from movement to temperature control, is dictated by G-code commands. Key commands related to preheating and leveling include:
M104: Sets the extruder temperature.M109: Waits for the extruder to reach the target temperature.M140: Sets the heated bed temperature.M190: Waits for the bed to reach the target temperature.G28: Homes the printer’s axes.G29: Activates auto bed leveling (ABL).
Modifying your slicer’s start G-code allows you to dictate when the extruder heats relative to the leveling sequence. For example, placing M104 before G29 will initiate preheating before bed leveling starts.
The Impact of Preheating on Print Quality
Preventing Adhesion Issues
When the extruder temperature is optimal, the filament flows smoothly and adheres properly to the bed. If preheating is skipped or delayed, the under-melted filament can warp or fail to stick, compromising the print’s foundation.
Avoiding Extrusion Problems
Temperature inconsistencies can lead to under-extrusion, leaving gaps in layers or over-extrusion, resulting in filament blobs. Preheating prevents such anomalies by ensuring the nozzle is at the correct temperature from the start.
Enhancing First-Layer Accuracy
Preheating ensures the components (nozzle and bed) are dimensionally stable before calibration. This improves nozzle positioning, resulting in an even, precise first layer. A well-set first layer significantly reduces the chances of post-processing errors.
Troubleshooting and Optimization Tips
While extruder preheating often works seamlessly, specific issues may arise. Here’s how to troubleshoot and optimize for a smooth printing experience:
Common Issues and Solutions
1. Extruder Heats Before Bed Reaches Target Temperature
This might cause the nozzle to ooze filament, creating stringing or blobs before leveling.
Solution: Use the M190 command to prioritize bed heating before starting nozzle preheating. Sequence your start G-code as:
M140 S[bed_temp]
M190 S[bed_temp]
M104 S[hotend_temp]
M109 S[hotend_temp]
2. Delayed Print Start
Sequential heating of the bed and extruder can increase startup time.
Solution: Use parallel heating by placing M104 and M140 together, followed by M109 and M190. This allows both components to heat simultaneously, saving time.
3. Heating Conflicts in Firmware
Some firmware imposes standard heating sequences that override custom G-code.
Solution: Check your firmware documentation and adjust settings to align with built-in logic. Ensure firmware updates are applied for better G-code compatibility.
Optimizing Auto Bed Leveling (ABL)
Preheating is critical when your printer uses ABL because temperature changes affect bed topology. Use the following tips:
- Verify that your firmware includes commands like
G29to measure the heated bed’s topography. - Adjust the Z-offset in the printer’s settings if preheating introduces flaring or flattening in the first layer.
- Regularly recalibrate when changing filaments or bed surfaces.
Expanding Technical Details for Enthusiasts
Role of Auto Bed Leveling in Precision
ABL sensors such as BLTouch or inductive probes measure bed irregularities and adjust leveling accordingly. These sensors can factor thermal expansion into their calculations by preheating before leveling, ensuring consistent Z-offsets.
Advanced G-code Modifications
Experts can refine their G-code sequences to account for specific scenarios:
- Adding temperature “stabilization pauses” with commands that hold temperatures steady for better calibration accuracy.
- Using
M420 S1to enable pre-saved leveling meshes after startup.
Frequently Asked Questions
What is the purpose of the extruder heating before leveling?
Heating ensures accurate calibration by accounting for nozzle expansion and provides optimum adhesion conditions for the first layer.
How can I adjust the G-code to prevent heating during leveling?
Modify your start G-code by placing extruder heating (M104, M109) after leveling (G29). This delays nozzle heating until leveling is complete.
Why does my printer extrude filament when heating the nozzle?
This occurs due to oozing, where filament melts and flows out of the nozzle during preheating. Reducing retraction distance and adding stabilization pauses can help.
What temperature should the nozzle and bed be during leveling?
For standard filaments like PLA, the nozzle is typically set between 190°C and 220°C, and the heated bed is between 50°C 60°C. Check each filament’s guide for exact values.
Can preheating affect leveling sensors like BLTouch?
Yes. Temperature-related material expansion can shift the trigger height of sensors. For maximum accuracy, always calibrate at operational printing temperatures.
What should I do if the firmware overrides my G-code?
Review the firmware’s heating logic and ensure your G-code aligns with its sequence. Updating the firmware may unlock more customization options.
Why might the extruder heat before the bed reaches the target temperature?
The G-code sequence often determines this behavior. Setting M190 before M109 will prioritize full bed heating before the extruder starts preheating.
How can I adjust my settings to save time during startup?
To reduce delays, use parallel heating by combining M104 M140 commands followed by M109 and M190. This will allow the bed and extruder to heat simultaneously.
How do Auto Bed Leveling sensors work during pre-level heating?
ABL sensors measure the bed’s topography and adjust Z-offsets. Heating before leveling ensures the measurements account for thermal expansion in the bed and nozzle.
What should I do if preheating causes the filament to ooze or string?
You can reduce oozing by adding a cleaning command or adjusting the G-code to heat the extruder only after completing the leveling routine.
What is the correct sequence of G-code commands for optimal preheating?
An optimized sequence typically starts with:
M140– Set bed temperature.M190– Wait for the bed to reach the target temperature.M104– Set extruder temperature.M109– Wait for the extruder to reach the target temperature.
Use these in the correct order for efficient heating and leveling.
How do temperature changes affect print quality during leveling?
Temperature variations can lead to material expansion and contraction. Preheating ensures dimensional stability, improving first-layer adhesion and print accuracy.
Can I calibrate my extruder during the preheating process?
Yes, you can use G-code commands like G92 (for extruder position) and G1 (for precise extrusion adjustments) to calibrate while the printer reaches operating temperatures.
How do I ensure my extruder and bed reach the proper temperatures?
Verify temperature settings in your slicer software, maintain clean thermistors, and inspect heater connections. Update firmware if required for better temperature control.
The Bottom Line
Preheating the extruder before leveling might seem small, but it’s vital for achieving high-quality prints. This feature optimizes adhesion, accounts for thermal expansion, and ensures precise leveling, laying the groundwork for success. Tailoring your printer’s firmware and G-code can enhance your workflow further, making each print smoother and more efficient.
Understanding and leveraging pre-leveling heating lets you control every aspect of your 3D printing process. Whether you’re a hobbyist or an advanced user, experimenting with these settings will help you unlock better precision and reliability in your prints.
Source:
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Prusa3D Forum: This forum discusses configuring hot-end heating after auto-leveling, including G-code sequences to optimize preheating and minimize filament oozing.
Link to source -
Ultimaker Community: A discussion on auto bed leveling while the nozzle and bed heat up, providing insights into simultaneous heating and its impact on print quality.
Link to source -
3D Printing Stack Exchange: A detailed explanation of simultaneous heating of the extruder and bed, including G-code examples and efficiency tips for preheating.
Link to source
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