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Raster Engraving

Raster engraving fills areas with back-and-forth scanning lines, similar to how an inkjet printer works. It's ideal for creating images, text, and filled designs on materials like wood, leather, and anodized aluminum.

Overview

Raster operations:

  • Fill closed shapes with scanning lines
  • Support variable power for grayscale images
  • Work with both vector shapes and bitmap images
  • Use bidirectional scanning for speed
  • Create permanent marks on many materials

When to Use Raster

Use raster engraving for:

  • Engraving text and logos
  • Creating images and photos on wood/leather
  • Filling solid areas with texture
  • Marking parts and products
  • Creating grayscale artwork

Don't use raster for:

  • L Cutting through material (use Contour instead)
  • L Precise outlines (raster creates filled areas)
  • L Fine line work (vectors are cleaner)

Creating a Raster Operation

Step 1: Prepare Content

Raster works with:

  • Vector shapes - Filled with scanning lines
  • Text - Converted to filled paths
  • Images - Converted to grayscale and engraved

Step 2: Add Raster Operation

  • Menu: Operations Add Raster
  • Shortcut: Ctrl+Shift+R
  • Right-click: Context menu Add Operation Raster

Step 3: Configure Settings

Key Settings

Power & Speed

Power (%):

  • Laser intensity for the engraving
  • Lower power for lighter marking
  • Higher power for deeper engraving
  • Typical range: 20-60% for engraving

Speed (mm/min):

  • How fast the laser scans
  • Faster = lighter, slower = darker
  • Typical range: 2000-5000 mm/min

Starting values (wood engraving):

  • Power: 30-50%
  • Speed: 2500-4000 mm/min
  • Always test on scrap material!

Line Interval

Line Interval (mm):

  • Spacing between scan lines
  • Smaller = higher quality, longer job time
  • Larger = faster, visible lines
Interval Quality Speed Use For
0.05mm Highest Slowest Photos, fine detail
0.1mm High Medium Text, logos, graphics
0.2mm Medium Fast Solid fills, textures
0.3mm+ Low Fastest Draft, testing

Recommended: 0.1mm for general use

Resolution Match

For images, line interval should match or exceed image resolution. If your image is 10 pixels/mm (254 DPI), use 0.1mm line interval or smaller.

Scan Direction

Scan Angle (degrees):

  • Direction of scan lines
  • 0 = horizontal (left to right)
  • 90 = vertical (top to bottom)
  • 45 = diagonal

Why change angle?

  • Wood grain: Engrave perpendicular to grain for better results
  • Pattern orientation: Match design aesthetics
  • Reduce banding: Different angle can hide imperfections

Bidirectional Scanning:

  • Enabled: Laser engraves in both directions (faster)
  • L Disabled: Laser only engraves left-to-right (slower, more consistent)

For best quality, disable bidirectional. For speed, enable it.

Overscan

Overscan Distance (mm):

  • How far beyond the design the laser travels before turning around
  • Allows laser to reach full speed before entering the design
  • Prevents burn marks at line starts/ends

Typical values:

  • 2-5mm for most jobs
  • Larger for high speeds
  • See Overscan for details

Grayscale Images

Raster operations can vary laser power based on image brightness:

Image Preparation

  1. Convert to grayscale - Color images are converted automatically
  2. Adjust contrast - Increase contrast for better engraving
  3. Increase brightness - Dark images may over-engrave
  4. Resize - Match your desired output size

Power Mapping

  • White pixels Laser off (0% power)
  • Gray pixels Proportional power (e.g., 50% gray = 50% of max power)
  • Black pixels Maximum power setting

Example:

  • Max power setting: 60%
  • 50% gray pixel 30% actual power
  • 100% black pixel 60% actual power

Resolution

Image DPI vs Line Interval:

  • 254 DPI = 10 pixels/mm use 0.1mm line interval
  • 508 DPI = 20 pixels/mm use 0.05mm line interval

Higher resolution images require smaller line intervals for quality.

Tips & Best Practices

Material Selection

Best materials for raster:

  • Wood (natural variations create beautiful results)
  • Leather (burns to dark brown/black)
  • Anodized aluminum (removes coating, reveals metal)
  • Coated metals (removes coating layer)
  • Some plastics (test first!)

 Challenging materials:

  • Clear acrylic (doesn't show engraving well)
  • Metals without coating (requires special marking compounds)
  • Glass (requires special settings/coatings)

Quality Settings

For best quality:

  • Use smaller line interval (0.05-0.1mm)
  • Disable bidirectional scanning
  • Increase overscan (3-5mm)
  • Use lower power, multiple passes
  • Ensure material is flat and secured

For faster engraving:

  • Use larger line interval (0.15-0.2mm)
  • Enable bidirectional scanning
  • Minimum overscan (1-2mm)
  • Single pass at higher power

Common Issues

Burn marks at line ends:

  • Increase overscan distance
  • Check acceleration settings
  • Reduce power slightly

Visible scan lines:

  • Decrease line interval
  • Reduce power (over-burning creates gaps)
  • Check that material is flat

Uneven engraving:

  • Ensure material is flat
  • Check focus consistency
  • Verify laser power stability
  • Clean laser lens

Banding (dark/light stripes):

  • Disable bidirectional scanning
  • Check belt tension
  • Reduce speed
  • Try different scan angle

Material Settings

Material Power Speed Line Interval Notes
Birch plywood 35-45% 3000-4000 mm/min 0.1mm Nice contrast
Cherry wood 30-40% 3500-4500 mm/min 0.1mm Rich dark color
Leather 25-35% 3000-4000 mm/min 0.1mm Test on scrap
Anodized aluminum 40-50% 4000-5000 mm/min 0.1mm Removes coating
Cork 20-30% 3500-4500 mm/min 0.15mm Very forgiving

Settings vary by laser type and material quality. Always test!

Advanced Techniques

Crosshatch Engraving

Run raster operation twice at different angles:

  1. First pass: 0 (horizontal)
  2. Second pass: 90 (vertical)

Creates deeper, more uniform engraving with crosshatch pattern.

Variable Line Interval

For large areas:

  • Use fine interval (0.05mm) for detailed areas
  • Use coarse interval (0.2mm) for solid fills
  • Combine multiple raster operations

Dithering

For photo engraving:

  • Convert images to dithered black & white
  • Creates halftone-like effect
  • Better detail than pure grayscale on some materials

Troubleshooting

Engraving too light

  • Increase: Power setting
  • Decrease: Speed setting
  • Check: Focus is correct
  • Try: Multiple passes

Engraving too dark/burning

  • Decrease: Power setting
  • Increase: Speed setting
  • Increase: Line interval
  • Check: Material is appropriate

Inconsistent darkness

  • Check: Material is flat
  • Check: Focus distance is consistent
  • Verify: Laser beam is clean
  • Test: Different area of material (grain varies)

Image looks pixelated

  • Decrease: Line interval
  • Check: Source image resolution
  • Try: Smaller line interval (0.05mm)
  • Verify: Image isn't being upscaled

Scan lines visible

  • Decrease: Line interval
  • Reduce: Power (over-burning creates gaps)
  • Try: Different scan angle
  • Ensure: Material surface is smooth

Technical Details

Scan Pattern Generation

Rayforge converts filled shapes to scan lines:

  1. Determine bounding box
  2. Calculate scan lines at specified angle and interval
  3. Clip lines to shape boundaries
  4. Add overscan extensions
  5. Optimize scan order (reduce travel time)
  6. Generate G-code

Bidirectional Scanning

Enabled (faster):

 Scan line 1
 Scan line 2
 Scan line 3

Disabled (more consistent):

 Scan line 1
  (return)
 Scan line 2
  (return)
 Scan line 3

G-code Example

G0 X-2 Y10          ; Move to overscan start
M3 S102             ; Laser on at 40% power
G1 X52 Y10 F3000    ; Scan line at 3000 mm/min
M5                  ; Laser off
G0 X52 Y10.1        ; Move to next line
M3 S102             ; Laser on
G1 X-2 Y10.1 F3000  ; Scan back (bidirectional)
M5                  ; Laser off