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Calibrating Your Workspace

Ensure your laser cuts accurately to the dimensions you design.

Goal

Verify and calibrate your laser's dimensional accuracy so that a 100mm square in Rayforge cuts as a true 100mm square on your material.

Prerequisites

  • Rayforge installed and connected to your laser
  • Machine homed and ready
  • Test material (cardboard, plywood, or acrylic scrap)
  • Ruler or calipers (digital calipers preferred for accuracy)
  • Basic understanding of machine settings

Why Calibration Matters

Laser machines use stepper motors with a configured steps-per-millimeter setting. If this setting is incorrect:

  • Parts won't fit together properly
  • Dimensions will be consistently off (e.g., 100mm design cuts as 98mm or 102mm)
  • Assembly projects will fail

Calibration ensures: 1mm in Rayforge = 1mm on your material

Step 1: Check Current Machine Configuration

First, verify your machine dimensions are configured correctly in Rayforge.

Open machine settings:

  1. Navigate to Settings > Machine > Profile
  2. Check Work Area dimensions:
  3. Width: Should match your laser bed width (e.g., 300mm)
  4. Height: Should match your laser bed height (e.g., 400mm)
  5. Check Origin Position:
  6. Top-left, bottom-left, or center (must match your actual machine)
  7. Check Y-axis Direction:
  8. Does Y increase upward or downward? (must match your machine)

If dimensions are wrong: Correct them now and save settings.

Step 2: Create a Test Pattern

Create a simple test pattern with known dimensions.

Design the test:

  1. Create a new project in Rayforge
  2. Add a square workpiece:
  3. Width: 100mm
  4. Height: 100mm
  5. Add a second rectangle workpiece:
  6. Width: 50mm
  7. Height: 100mm
  8. Position them with some spacing

Why these dimensions?

  • 100mm is easy to measure
  • 50mm tests both axes independently
  • Multiple shapes verify consistency

Step 3: Configure Cut Settings

Set up appropriate cut settings for your test material.

For cardboard test (fast and cheap):

  • Operation: Contour
  • Power: 15-20% (just enough to cut through)
  • Speed: 1500-2000 mm/min
  • Passes: 1

For plywood test (more accurate):

  • Operation: Contour
  • Power: 60-80%
  • Speed: 300-500 mm/min
  • Passes: 1-2

For acrylic test (most accurate):

  • Operation: Contour
  • Power: 80-100%
  • Speed: 150-200 mm/min
  • Passes: 1

Step 4: Preview and Frame

Before cutting, verify the job will run in the correct location.

Frame the job:

  1. In Rayforge, click Frame Job (or use keyboard shortcut)
  2. Laser head will trace the outline of the job boundary
  3. Verify:
  4. Position is correct on your material
  5. Job fits within work area
  6. No collisions with clamps or obstacles

If position is wrong: Adjust job origin or reposition material.

Step 5: Cut the Test Pattern

Run the calibration test cut.

Safety first:

  • Ensure ventilation is running
  • Have fire extinguisher ready
  • Stay near the machine (never leave unattended)

Run the job:

  1. Click Start Job in Rayforge
  2. Monitor the cut closely
  3. Wait for completion
  4. Allow material to cool before removing

Step 6: Measure the Results

Carefully measure the cut pieces to determine accuracy.

What to measure:

  1. 100mm square:
  2. Measure width (X-axis): Should be 100.0mm
  3. Measure height (Y-axis): Should be 100.0mm
  4. 50mm x 100mm rectangle:
  5. Measure width: Should be 50.0mm
  6. Measure height: Should be 100.0mm

Measurement tips:

  • Measure from cut edge to cut edge (ignore kerf)
  • Take 3 measurements and average them
  • Use calipers for best accuracy (rulers are less precise)

Record your results:

Target: 100mm x 100mm square
Actual: ___mm x ___mm

Target: 50mm x 100mm rectangle
Actual: ___mm x ___mm

Step 7: Calculate Calibration Error

Determine how far off your machine is from true dimensions.

Calculate error percentage:

Error (X-axis) = (Measured Width - Target Width) / Target Width * 100%
Error (Y-axis) = (Measured Height - Target Height) / Target Height * 100%

Example:

Target: 100mm x 100mm Actual: 98.5mm x 101.2mm

X error = (98.5 - 100) / 100 * 100% = -1.5%
Y error = (101.2 - 100) / 100 * 100% = +1.2%

Interpretation:

  • X-axis is cutting 1.5% too small
  • Y-axis is cutting 1.2% too large

Step 8: Determine if Calibration is Needed

Decide if your accuracy is acceptable or needs correction.

Accuracy thresholds:

Application Acceptable Error Action
Artistic/decorative ± 2mm (2%) Probably OK as-is
General projects ± 0.5mm (0.5%) Calibrate if outside this
Precision/assembly ± 0.1mm (0.1%) Calibrate, verify hardware

If within tolerance: You're done! No calibration needed.

If outside tolerance: Proceed to Step 9.

Step 9: Adjust Firmware Settings (GRBL)

Correct dimensional errors by adjusting steps-per-mm in firmware.

Understanding Steps-Per-Millimeter

Your machine's controller needs to know how many motor steps equal one millimeter of movement.

Default GRBL settings:

  • $100: X-axis steps/mm (typical: 80-100)
  • $101: Y-axis steps/mm (typical: 80-100)

If parts are too small: Increase steps/mm If parts are too large: Decrease steps/mm

Calculate New Settings

Formula:

New steps/mm = Current steps/mm * (Target dimension / Measured dimension)

Example:

Current X steps/mm: $100 = 80.00 Target: 100mm Measured: 98.5mm

New X steps/mm = 80.00 * (100 / 98.5) = 81.22

Current Y steps/mm: $101 = 80.00 Target: 100mm Measured: 101.2mm

New Y steps/mm = 80.00 * (100 / 101.2) = 79.05

Read Current Settings

In Rayforge console:

  1. Open Console tab
  2. Send command: $$ (two dollar signs)
  3. Firmware will respond with all settings
  4. Note current values for $100 and $101

Example output:

$100=80.000
$101=80.000
$102=80.000
...

Update Settings

Send new values:

In the Rayforge console:

$100=81.22
$101=79.05

Wait for "ok" response from firmware.

Save Settings

GRBL automatically saves settings to EEPROM, but verify:

$$

Check that $100 and $101 now show the new values.

Step 10: Verify Calibration

Cut another test pattern to confirm accuracy.

Repeat the test:

  1. Use the same test pattern (100mm square, 50mm rectangle)
  2. Cut on fresh material
  3. Measure results again
  4. Verify dimensions are now accurate

Expected results:

Target: 100mm x 100mm
Actual: 100.0mm +/- 0.2mm x 100.0mm +/- 0.2mm

If still off: Repeat calibration process. Large errors may require multiple iterations.

If now accurate: Calibration complete!

Advanced Calibration

Belt Tension and Mechanical Issues

If calibration doesn't solve dimensional errors, check mechanical components:

Symptoms of mechanical issues:

  • Errors vary between tests (not consistent)
  • One axis much worse than the other
  • Dimensions change based on speed

Check:

  1. Belt tension:
  2. Should be tight but not over-tensioned
  3. Loose belts cause backlash and dimensional errors
  4. Pulley set screws:
  5. Ensure pulleys are tight on motor shafts
  6. Loose pulleys slip and cause errors
  7. Linear rails:
  8. Should move smoothly without binding
  9. Clean and lubricate if needed
  10. Stepper drivers:
  11. Verify current settings are correct
  12. Underpowered motors can skip steps

Kerf Compensation vs Calibration

Kerf is the material removed by the laser beam (typically 0.1-0.3mm).

Kerf is NOT a calibration issue:

  • Kerf makes parts slightly smaller than designed
  • Kerf is compensated in Rayforge settings (see Overscan & Kerf)

Calibration corrects:

  • Systematic dimensional errors across the entire workspace
  • Steps-per-mm configuration errors

If your 100mm square measures 99.8mm: This might be kerf, not calibration error.

Testing at Different Scales

For precision work, test calibration at multiple scales:

Create test patterns:

  • Small: 20mm x 20mm square
  • Medium: 100mm x 100mm square
  • Large: 200mm x 200mm square

Measure all three:

  • Errors should be proportional (e.g., 1% error at all scales)
  • If errors vary by scale, there may be mechanical non-linearity

Troubleshooting

Dimensions Off by Large Amount (>5%)

Possible causes:

  • Wrong firmware settings
  • Wrong machine profile in Rayforge
  • Mechanical issue (loose pulley, belt)

Solutions:

  • Verify machine work area dimensions in settings
  • Check \(100/\)101 settings in firmware
  • Inspect mechanical components

Dimensions Inconsistent Between Tests

Possible causes:

  • Loose belts or pulleys
  • Stepper motors skipping steps
  • Material warping or movement during cut

Solutions:

  • Tighten belts to proper tension
  • Verify stepper driver current settings
  • Secure material better, use flat material

One Axis Accurate, One Axis Wrong

Possible causes:

  • One axis has incorrect steps/mm
  • Mechanical issue on one axis only

Solutions:

  • Calibrate the problem axis separately
  • Inspect that axis's belt, pulley, rails

Still Inaccurate After Calibration

Possible causes:

  • Measurement error (using inaccurate ruler)
  • Kerf not accounted for (measure outer edge to outer edge)
  • Severe mechanical issues

Solutions:

  • Use digital calipers for accurate measurement
  • Re-check calculation of new steps/mm
  • Consult machine manufacturer documentation

Best Practices

  1. Calibrate when:

  2. Setting up a new machine

  3. After replacing belts or pulleys
  4. If dimensional errors are noticed

  5. Periodically (every 6-12 months)

  6. Use good test materials:

  7. Flat, stable materials (not warped)

  8. Acrylic or plywood preferred over cardboard

  9. Large enough to measure accurately

  10. Measure carefully:

  11. Use calipers, not rulers

  12. Take multiple measurements and average

  13. Measure edge to edge, not including kerf

  14. Document your settings:

  15. Record $100 and $101 values

  16. Note any mechanical adjustments

  17. Keep calibration test results for reference

  18. Re-verify periodically:

  19. Test dimensional accuracy on actual projects
  20. Re-calibrate if you notice consistent errors