Two-sided pieces, such as ornaments, gift tags, coasters and signs, only look right when the back lands exactly behind the front. The laser cannot see through the part, so alignment comes from a reference that does not move: a jig, a fixed origin and a test you can measure.
1. Cut a jig the part cannot move in
Fix a sacrificial sheet of card or MDF to the bed and cut a pocket the shape of the part from it, using the same outline as the part. Do not move the sheet until both sides are done. For a true-scale outline of a common part, start from the free outline library.
2. Lock the origin
Run every job for both sides from a fixed origin, such as LightBurn's Absolute Coords or a User Origin you set once and leave, never from Current Position, which moves with the head. If the origin is fixed, the pocket and the art share one coordinate system.
3. Flip about the right line
Decide the flip axis first, usually left to right. A part whose outline is symmetric about that axis drops back into the same pocket after the flip. An asymmetric part, such as a tag with an off-centre hole, will not: cut a second pocket from the mirrored outline at the same origin. Design the back to read correctly, and place its elements by mirroring their position about the pocket's centre line, not by mirroring the art.
4. Prove it with targets
The free layer registration target has four crosshair targets centred 80 mm apart. Burn them on a scrap blank, flip it in the jig and burn them again. Crosshairs that land on each other mean the setup is right; an offset tells you the direction to correct. If the burned spacing is not 80 mm, the job is scaling on import or the machine needs its steps checked, and no amount of jig work will fix that.
5. Engrave both faces, cut last
When the parts are cut from a sheet, engrave both faces before cutting the outlines free, so the part never moves independently of its reference. Keep the scrap with the aligned targets beside the machine as proof of the setup, and re-check it whenever the jig is rebuilt.
Frequently asked questions: Workflow
Why is the second side offset from the first?
Almost always because the reference moved: the job started from the laser head's current position instead of a fixed origin, the jig shifted, or the part did not seat fully in its pocket. Burn registration targets on scrap to find out which, before you blame the machine.
Do I mirror the artwork for the back?
No. Design the back to read correctly from the back. What flips is position: anything off-centre on the front lands on the opposite side of the centre line after the flip, so place back-side elements by mirroring their position about that line, not by mirroring the art.
Does this work on a fiber or galvo machine?
The same principle applies: a fixture that holds the part in the same place in the marking field, and a target marked on the fixture to check it. Keep the part flat and at the same focus height for both sides.