1. What is focus of laser engraver?

Laser focusing is a crucial operation that via adjusting the focal position of the laser beam to make it precisely land on the surface of the material. At the focal point, the laser beam will converge into the smallest light spot. At this moment, the energy density is the highest, enabling efficient cutting or engraving of the material. If there is a deviation in the focal position, it will cause the light spot to expand and the energy to disperse, thus affecting the fineness of the engraving and the depth of the cutting. To put it in a more popular way, focusing is like "sharpening the tip of the pencil" or using a magnifying glass to focus the sunlight to ignite a piece of paper. Only when the focal point is aligned correctly can sufficient energy be generated. The principle of laser focusing is similar.

2. Why is it necessary to focus before laser engraving?

2.1 There are two circumstances:

• Focus Accuracy: Achieve an ultra-fine line width of 0.06mm (at a wavelength of 1064nm) and 0.15mm (at a wavelength of 455nm) (such as precision QR codes and micro text).
  
• Misalignment of focus: The diffusion of light spots leads to blurred engraving edges and loss of details.
  

2.2 Focusing is a "calibration" step before laser engraving, which directly affects the quality of the finished product. If focusing is skipped, the following issues may occur:

• Blurred or uneven engraving: When the focus deviates, the laser energy disperses, making it difficult to accurately ablate the surface of the material.
  
• Material damage: Excessive focus may burn the surface of the material; If the focus is too low, it may not be able to penetrate thick materials.
• Waste of time and resources: Waste products caused by focusing errors need to be remade, which increases costs.

2.3 Common misconceptions among beginners:

• The machine can be used directly after purchasing without adjustment - in fact, different materials and thicknesses require refocusing.
  

3. Guide for Focus of EM-Smart Dual

3.1 Electric focusing 

• Precise control: Users can achieve different movement steps by clicking and long pressing the keypad. Clicking achieves fine adjustment of the focus for smaller step size, while long pressing achieves fast movement of the focus for larger step size.
• Focusing speed: The key board controls the motor rotation to drive the lead screw to rotate and cooperate with the slider to move up and down. The high-precision processing of the lead screw and the precise cooperation of the pulley enable the lifting to maintain extremely high straightness and stability during the movement, thereby achieving fast and accurate focusing.
• Applicable situation: Suitable for all situation including shallow engraving, deep engraving, etc.
  

Steps:

• Machine check: Ensure machine supports the fouction of electric focusing.
• Lanuch relevant software: Find "Electric Focusing" in the software (usually lies in the menu of"setting"or"tools")
  
• Start focusing: Click "Start" button, then the laser automatically descends and springs back to the optimal height when it touches the surface of the material.
  
• Verify the circumstance: Use the scarp material to engrave a straight and short line, and observe whether it is clear and free of burrs.
  

3.2 Manual focusing

• Direct operation: Manual focusing requires users to directly control the meshing of gears through an external knob to drive the lead screw to rotate and the pulley to move up and down, suitable for scenes that require precise focus control.
  
• Applicable situation: Curved objects (such as cups), textured materials (such as leather), reflective materials (such as stainless steel), etc.

Matters needing attention:

Wear laser protection goggles when focusing to avoid accidental laser irradiation. You can also use your phone camera to zoom in on the image and observe if the focus is accurate.

4. Tips for focusing

• In situation where electric focusing is difficult to accurately focus, such as low-light environment, solid color backgrounds, and ultra long or ultra close range shooting, manual focusing is more effective.
  
• When the focus is on the surface of the material, the energy is most concentrated and suitable for shallow engraving or cutting. However, deep engraving requires layer by layer removal of materials. If the focus remains on the original surface, as the engraving depth increases, the laser beam will be defocused (the distance between the focus and the processing surface increases) and the energy will be dispersed. Therefore, adjusting the focal length downwards (such as 0.1-0.5mm) can make the focus position closer to the actual processing surface (i.e., the bottom of the formed groove) during the engraving process, maintain energy concentration, and improve the efficiency and uniformity of deep engraving.

5. FAQs

5.1 Fail to electric focusing: Usually caused by a dirty lens, uneven surface, or abnormal device connection.

Solution: Firstly, turn off the power and clean the lens with a cotton swab made of anhydrous alcohol; Or switch to manual focusing mode; Ensure that the material is flat and fixed with fixtures; You can also unplug and restart the device. Regular maintenance of the lens and avoiding operation in dusty environments can prevent this problem.

5.2 Blurred engraving effect or rough edges: Focus offset, lens contamination, loose materials, or mismatched parameters are the main reasons.

Solution: Refocus and use waste material to test engraving a "crosshair" to verify clarity; Wipe the lens with lens cleaner to avoid direct contact; fix materials to prevent movement; Gradually adjust the power (± 5% each time) or speed (such as adjusting to 1000mm/s) to find the best combination. Before engraving, it is necessary to conduct small-scale testing to avoid large-scale errors.

5.3 The effects of different materials vary greatly: wood that is prone to burning can increase the focal point by 0.5-1mm and reduce power; Acrylic needs to be aligned with the focus. Remove the protective film to prevent contamination, so that the final work can be clear and accurate. The metal coating should increase the focal point by 0.2mm and significantly reduce the power to 15% -20%.

Solution: It is recommended to establish parameter files for each material, record relevant parameters, and refer to the parameter table provided by the manufacturer to adjust according to the actual situation.

5.4 Uneven surface engraving: insufficient depth of focus (>± 0.5mm drop)

Solution: Use a rotating attachment to fix the cylinder and input the circumference, with the highest point of the surface as the focus point; Complex surfaces can be segmented for focusing and set to different Z-axis heights, gradually completed with layered engraving. Reduce power during engraving to prevent burning through, and prioritize testing the effect with light colored materials. 

5.5 Burning or yellowing of engraved edges: High focus or slow speed are common causes.

Solution: Refocus to ensure that the two positioning red lights coincide on the surface, and observe the engraving effect during the trial engraving; Improve speed and shorten laser dwell time, and slightly increase power if necessary. Metal can be cooled by spraying water on the surface, while leather requires a combination of low power and high speed.

6. Conclusion

Laser focusing is the cornerstone of engraving accuracy, and the core logic needs to be mastered through practice. Suggest establishing a personal parameter library to record the focal height and processing effect of different materials (such as wood, acrylic, metal), gradually understanding the response law of material characteristics to energy. Novices can start with simple materials, accumulate experience through trial engraving methods, and then advance to explore surface engraving or deep engraving modes. Every calibration is a process of technical precipitation. By maintaining patience and recording habits, you will grow into a true process controller through error correction. Activate EM-Smart Dual SE and let the laser accurately interpret your creativity!