Why a jig beats placing blanks by eye
A batch of 40 name tags on a laser is a positioning problem, not an engraving problem. Camera preview gets you close, but a tag that sits 1 mm off on a 50 mm keychain is visible, and you will not see it until the name is burned in. A laser engraving jig fixes every blank to a known spot so the same job runs again and again with only the blanks changing.
There are two ways to get a jig: download one of the many free laser engraving files and hope the sizes match, or make one for the blanks you actually bought. The second takes ten minutes and removes the guessing. The jig generator builds the pocket layout from your measured blank, your laser’s bed and the clearance you choose.
The cut-in-place trick
The single most useful idea for laser jigs: cut the jig on the bed and do not move it afterward.
When the laser cuts the pockets, the pocket outlines are created in the machine’s own coordinate system. If the jig stays put, the engraving job that follows uses the same coordinates, so each design lands in the middle of its pocket. Any error in camera calibration, bed squareness or job origin affects the jig and the artwork equally and cancels out.
What breaks it:
- Lifting the jig to clean under it, or bumping it while swapping blanks. Tape all four corners or pin it.
- Running the jig cut from one origin mode and the engraving from another.
- Changing the lens or field size on a galvo between the cut and the engrave (LightBurn notes that changing lenses means repeating setup and calibration).
If you need to remove the jig, give it a hard reference: butt it against a corner stop screwed or taped to the bed, and engrave origin marks on both the jig and the bed. The generator puts origin marks on its engrave layer for this.
Kerf: the pocket is bigger than the line
A laser cut removes material. LightBurn defines kerf as the material removed by the tool, and its width depends on material, thickness, speed and power. On a pocket, the beam runs along the drawn line, so the hole comes out larger than drawn. The amount is small but matters on a jig:
| Source | Laser | Kerf stated |
|---|---|---|
| University of Waterloo lab listing | Epilog Fusion M2 40, 75 W CO2 | 0.1–0.175 mm, material dependent |
| University of Waterloo lab listing | Trotec Speedy 300, 80 W CO2 | 0.1 mm, material dependent |
| LightBurn vernier kerf test, worked example | Any | 0.0575 mm (illustration of the calculation) |
Two ways to deal with it:
- Kerf offset in software. LightBurn’s Kerf Offset moves closed shapes outward with a positive value and inward with a negative one, and inverts the direction for shapes inside other shapes on the same layer, so holes come out the right size. xTool’s kerf offset accepts −1 to 1 mm, and xTool says the theoretical value is 0.5 × the laser spot diameter, but advises testing on your material.
- Fold it into clearance. Leave kerf offset at zero and pick the clearance from a test-fit coupon cut on the same laser. Whatever the kerf is, the coupon already includes it, and you never have to remember which layers carry an offset. The jig clearance guide has starting values.
Sacrificial jig materials
| Material | Good for | Notes |
|---|---|---|
| Corrugated cardboard | One-off batches, quick tests | Cuts in one fast pass; flutes can crush, so not for heavy blanks |
| 3 mm MDF or plywood | Reusable jigs for a product you sell every week | Holds pocket shape; can bow with humidity, so tape the corners |
| Cast acrylic | Long-life jigs, two-layer jigs | Clean edges; melts slightly at the cut edge, so test clearance on acrylic specifically |
For a deeper comparison, including 3D-printed jigs, see best material for jigs.
The blank should be at least as thick as the jig sheet, or the sheet’s top edge sits higher than the blank. That matters less on a laser than on a UV printer, but on a diode or CO2 laser with a short focal depth, a tag that sits 2 mm below the jig surface can be noticeably out of focus if you focused on the jig. Always focus on the blank.
Setting the origin in LightBurn and xTool Studio
LightBurn has three Start From modes:
- Absolute Coordinates outputs graphics at the location that matches their position in the workspace. LightBurn notes this requires a laser with a fixed origin; machines without homing switches must be homed manually.
- Current Position places the job relative to wherever the head is when you press Start. Avoid it for jigs; a nudge of the head moves the whole batch.
- User Origin places the job relative to an origin you set beforehand. It works for jigs if you set it once and do not change it.
For galvo lasers, LightBurn states that galvos always use Absolute Coordinates. The workspace corresponds to the lens field, and the field position can be fine-tuned with Offset X/Y in Galvo and Basic Settings. As long as the jig stays under the lens, the coordinates do not drift.
On camera-based machines that run xTool Studio, you place the design over the camera image of the bed. Cut the jig with the camera image, leave it in place, and drop the artwork onto the same pocket positions. Re-take the camera image before each batch so you can see that every blank is seated.
Frame before every batch
Framing traces the outline of the job before the laser fires.
- On galvo lasers in LightBurn, framing uses a red dot that fires through the same optics as the marking laser. Bounds traces the smallest rectangle, Hull follows the outside of all graphics closely, and Contour traces the exact shapes. Contour is slowest but shows whether each name sits inside its tag.
- On xTool’s F2 Ultra UV, framing in xTool Studio moves the laser dots along the object boundaries in Rect, Outline or Polygon mode, and you can select specific objects to frame just those.
If the frame is off by the same amount on every pocket, the jig moved or the origin changed. If it is off by more at the edges of a galvo field, check focus height first; LightBurn’s framing docs point to focus and red dot settings when framing location or scale is off.
Numbering and order lists
For personalized batches, mistakes happen when the operator loads blank 7 where blank 8 should go. The generator engraves a number next to every pocket in stroke-font text on the blue layer, and exports a CSV of pocket centers in the same order. Sort your order list to match, and load and unload in that sequence.
Holding the jig on a honeycomb bed
Honeycomb beds let air through, but they also let thin jigs flex and lift. Honeycomb pins (small pegs pushed into the cells around the jig edge) hold it flat and act as reusable corner stops. Because cell sizes differ between machines, measure your honeycomb before cutting or printing pins. On steel honeycombs, magnets work too, as long as they do not sit inside the engraving path.
A worked example: 2 in round keychains on a Glowforge
Glowforge lists a cutting area of about 495 × 279 mm (19.5 × 11 in) for the Pro, Plus and Basic. For 2 in (50.8 mm) round keychain blanks with 0.2 mm clearance per side, 4 mm webs and an 8 mm margin round the plate (so the outer cut never runs along the edge of the bed):
- Pocket diameter: 50.8 + 2 × 0.2 = 51.2 mm. Pitch: 51.2 + 4 = 55.2 mm.
- Usable area: 495 − 16 = 479 mm by 279 − 16 = 263 mm.
- Across 479 mm: (479 + 4) ÷ 55.2 = 8.75, so 8 pockets.
- Down 263 mm: (263 + 4) ÷ 55.2 = 4.8, so 4 rows: 8 × 4 = 32 keychains in a square grid.
- Staggered rows nest each row into the gaps of the one above, so the row pitch drops to 55.2 × 0.866 = 47.8 mm and 5 rows fit: 5 × 8 = 40 keychains per run, 25% more from the same sheet.
The ready layout is on the Glowforge Pro 2 in keychain combo page, and other machine and blank pairs are in the combo index. Pricing a 40-piece run is covered in pricing batch laser and UV jobs.
Step by step
- Tape a sacrificial sheet flat to the bed and focus on it.
- Generate the jig in the generator from your measured blank, with clearance taken from a test-fit coupon.
- Engrave the pocket numbers, then cut the pockets from Absolute Coordinates or a saved User Origin. Leave the sheet in place.
- Load the blanks and refocus on the blank surface.
- Place each design on its pocket center in the same file and frame the job.
- Engrave, swap blanks in numbered order, and repeat.