Manual First Layer Calibration on the Kobra 3 (No Wizard)

The first layer is everything. If it's wrong, nothing sticks right. Here's how to manually calibrate without the built-in wizard.

What You Need

• A piece of A4 paper (about 0.1mm thick — good feeler gauge)
• 10 minutes
• Patience

Step 1 — Home All Axes

Run G28 from your host software (Orca Slicer console, OctoPrint, or LCD menu).

Step 2 — Disable Steppers But Keep Heated Bed

M84 X Y Z  ; disable X/Y/Z steppers only — keep E engaged
M140 S60   ; heat bed to print temp

Wait for bed to reach temp. Cold bed = false Z offset.

Step 3 — Move Nozzle to Test Points

Test 5 points: center + 4 corners. Move manually:

G0 X125 Y125 Z0  ; center
G0 X20 Y20 Z0    ; front left
G0 X230 Y20 Z0   ; front right
G0 X230 Y230 Z0  ; back right
G0 X20 Y230 Z0   ; back left

At each point: slide paper under nozzle. Should feel slight drag — not locked, not free.

Step 4 — Adjust Z Offset

In Orca Slicer or LCD: find Z Offset (Baby Step Z).

• Paper slides freely = nozzle too high → decrease Z offset (more negative)
• Paper won't move = nozzle too low → increase Z offset (less negative)
• Typical range: -0.1 to -2.5mm

Adjust in 0.05mm increments.

Step 5 — Print a Test Square

Print a 100×100×0.2mm single-layer square at 30mm/s. Look for:

Save the Value

Once happy: save Z offset in firmware (M500 via console or save in LCD menu).

Notes

• Re-calibrate after: nozzle change, PEI sheet swap, moving the printer
• PEI should be clean (IPA wipe) before every calibration
• First layer at 30mm/s always, regardless of print speed setting