G-code to Turn on Extruder Temperature: A Comprehensive Guide

Controlling extruder temperature is a foundational skill in 3D printing. You can optimize print quality, troubleshoot issues, and experiment with different materials through precise G-code commands. Whether you’re a novice or an experienced maker, understanding how to set and adjust extruder temperatures will significantly enhance your results. This guide will provide an in-depth exploration of using G-code for temperature control.

What is G-code and Why is it Important?

G-code is a standardized programming language that directs CNC machines and 3D printers. It consists of simple yet powerful instructions that control every movement, operation, and setting on your printer.

Purpose of G-code

G-code is the “bridge” between your slicing software and the printer’s firmware. It controls:

• The motion of the print head (X, Y, and Z axes).
• Heating elements like the nozzle and bed.
• Extrusion rates and speeds.
• Environmental adjustments like cooling fan speeds.

For example, when preparing a 3D model, slicing software converts it into a G-code file. The printer then interprets this file to execute instructions.

Why Focus on Extruder Temperature?

Extruder temperature is critical for:

• Proper Layer Adhesion: A well-heated filament will stick firmly to the bed and previous layers.
• Material Flow: Different filaments demand specific temperatures for smooth extrusion.
• Print Quality: Incorrect temperatures can lead to under-extrusion, oozing, or even print failure.

By using precise G-code commands, you can gain complete control over the extrusion process, ensure consistency, and reduce common printing issues.

Key G-code Commands for Extruder Temperature

The two most critical G-code commands for extruder temperature management are M104 and M109. Both serve unique purposes and are used at different points in the 3D printing process.

M104 – Set Temperature Without Waiting

The the the M104 command sets the extruder temperature to the target value but doesn’t pause the printer while heating. It is ideal for preheating during the initial setup.

Example:

M104 S200

Explanation:

• M104 adjusts the hot-end temperature.
• S200 sets the target value to 200°C.
• Other printer operations continue while the nozzle heats.

M109 – Set Temperature and Wait

The M109 command halts all operations until the extruder reaches the desired temperature. This is best for ensuring the nozzle is ready before printing begins.

Example:

M109 S200

Explanation:

• M109 adjusts the hotend temperature.
• The printer pauses until the target temperature (200°C) is reached.

When to Use Each Command:

• Use M104 during preparatory steps to save time.
• Use M109 right before extrusion to ensure optimal printing conditions.

How G-code Interacts with Firmware?

Firmware, such as Marlin or Klipper, is the software embedded in your 3D printer. It translates G-code into machine-level commands to drive hardware components like motors, heaters, and sensors.

Understanding Firmware Roles:

1. Interpreting G-code:
   The firmware reads G-code commands to determine actions (e.g., heat nozzle, move axis).

2. Safety Features:
   Advanced firmware includes safeguards:

   • Thermal Runaway Protection: Prevents overheating by shutting down components if anomalies are detected.
   • Preheating Thresholds: Limits temperatures to predefined ranges to avoid hardware damage.

3. Customizations:
   Firmware like Klipper allows users to modify settings for unique printing needs, such as faster execution or precise thermal control.

Example of Interaction:

When running the command M109 S200, the firmware:

• Activates the heater cartridge to reach 200°C.
• Utilizes the thermistor to monitor and stabilize the temperature.
• Returns control once the target temperature is confirmed.

Why Temperature Control Matters?

Maintaining the right extruder temperature can be the difference between a failed print and a masterpiece. Here’s why:

Filament Behavior at Different Temperatures:

• PLA:

  • Ideal Range: 190–220°C.
  • Too Low: Poor adhesion and stringy prints.
  • Too High: Excessive oozing and loss of detail.

• ABS:

  • Ideal Range: 230–250°C.
  • Too Low: Layer separation and weak prints.
  • Too High: Warping and degradation.

• PETG:

  • Ideal Range: 220–250°C.
  • Too Low: Under-extrusion.
  • Too High: Sticky, blobby layers.

Common Temperature-Related Issues:

1. Under-extrusion (low temperature): Results in weak layers or gaps.
2. Stringing (high temperature): Filament forms unwanted strands between parts.
3. Nozzle Clogs (incorrect temperature): Filament fails to melt or burns inside the nozzle.

Troubleshooting Tips:

• Verify thermistor placement to avoid false readings.
• Clean the nozzle regularly to maintain consistent extrusion.
• Use temperature towers to identify the optimal settings for each material.

Best Practices for Start G-code in Slicers

Start G-code prepares your 3D printer for a successful print by defining its initial actions.

Guidelines for Effective Start G-code:

1. Coordinate Heating:

   M190 S60      ; Heat bed to 60°C
   M104 S200     ; Preheat nozzle to 200°C
   M109 S200     ; Wait for nozzle to reach 200°C
   

2. Home the Printer:

   G28           ; Home all axes
   

   Ensures proper positioning.

3. Prime Filament Flow:

   G1 E10 F100   ; Extrude a small amount of filament
   

Advanced Customizations:

• Conditional Statements:
  Use if/else logic to adjust settings based on filament type or pre-defined rules.
• Multi-Material Prints:
  Incorporate commands to switch nozzles or change filament mid-print.

Common Mistakes to Avoid:

• Forgetting bed leveling commands (G29) for automated printers.
• Incorrect sequence of heating commands leading to filament oozing.
• Overlooking nozzle priming, causing extrusion delays.

Practical Applications and Tips

Preheating:

Before printing, always preheat the nozzle and bed to ensure smooth adhesion and extrusion.

G-code Example:

M190 S65 ; Heat bed for PETG
M109 S240 ; Heat nozzle to 240°C

Dynamic Temperature Adjustments:

Mid-print temperature tweaks can optimize results:

• Lowering temperatures after the first layers can reduce stringing.
• Increasing temperatures gradually for tall, single-column prints enhances stability.

Using Temperature Towers:

Generate a test print that cycles through temperature values to determine the material’s optimal extrusion range.

Frequently Asked Questions

What is the difference between M104 and M109?

M104 sets the temperature without waiting, while M109 waits until the nozzle reaches the target temperature before proceeding.

Can I adjust temperatures mid-print?

You can use it M104 to adjust the temperature, but small changes are recommended to avoid defects.

How do I troubleshoot uneven temperatures?

Check your thermistor for proper alignment and ensure firmware limits are set correctly.

Should the bed or hotend be heated first?

Heat the bed first (M190), then the hotel (M109).

How does G-code work with slicers?

Slicers generate G-code by converting 3D models into a set of printable instructions.

What happens if I do not correctly set the temperature before a print?

Incorrect settings can lead to poor adhesion, under-extrusion, or nozzle clogging. Always verify temperatures before starting.

What does the G28 command do about the printer’s temperature settings?

The G28 command homes the printer’s axes, ensuring proper positioning before heating or printing begins.

How can I ensure my printer’s nozzle temperature is accurately set for PLA?

Use the M104 command to set the temperature within PLA’s recommended range (typically 190–220°C) and M109 to wait until the target is reached.

How do I use Simplify3D to adjust the extruder temperature in my G-code?

In Simplify3D, you can adjust extruder temperature settings in the ‘Temperature’ tab of the slicing settings. You can also create temperature towers for testing.

What is the purpose of the G92 command regarding the extruder?

The G92 command sets the current position of the tool head or extruder to specific coordinates, useful for resetting the extruder position after a tool change or at the start of a new print.

How does the M190 command interact with the extruder temperature and the heated bed?

The M190 command waits for the heated bed to reach a specified temperature before proceeding. It’s often used alongside extruder temperature commands to ensure both are correctly set before printing.

Can I set a new extruder temperature while a print is ongoing?

You can use the M104 command to set a new temperature during a print. However, drastic changes may affect print quality.

Conclusion

Mastering G-code for extruder temperature control unlocks a new level of precision in 3D printing. By implementing commands like M104 and M109 and customizing start G-code routines, you can achieve consistently high-quality prints across all materials. Take the time to experiment, troubleshoot, and fine-tune your settings, and you’ll be rewarded with flawless and reliable results every time.