How do I position a design accurately on a live edge slab or other irregular piece of wood?

The problem

Job setup assumes a rectangle with a clean corner or center to zero from. A live edge slab has neither, so a design that looks centered on screen can land off to one side on the wood.

The outline method

An educator's method puts the slab's real outline both in the software and on the machine:

1. Photograph the slab from directly above.
2. Import the photo and scale it to true size. Lay a ruler in the photo, or draw a box of a known measured dimension in the software, and stretch the image in proportion until the two match.
3. Trace the outline of the slab as a closed vector. Manual tracing with the drawing tools is usually cleaner than auto tracing a photo.
4. Lay out the design inside the traced outline, exactly where you want it on the wood.
5. Carve the outline onto the spoilboard as a shallow V-carved or profiled line.
6. Set the slab on the carved outline and clamp it. The slab is now in the same place on the machine as it is in the file, so the design lands where you drew it.

Depth on an uneven surface

• A slab that is not flat will carve deeper in high areas and shallower in low ones. Flatten the face first if the carving needs even depth.
• For areas at different heights, one educator sets up separate sheets with their own material setup, or in Aspire lowers the base height of the model for a smooth transition.
• Do not trim clearance heights too far on rough stock. The same educator cut nearly 2 hours from a 4.5 hour carve by lowering the retract from 0.2 to 0.1 inch, but warns against going below 0.1 inch because the bit can gouge uneven material while traveling.

Pro tips

• For repeat jobs, a physical fence on the table is more repeatable than typed offsets, which make it easy to confuse zero positions.
• Keep the photo on its own layer and hide or lock it once the outline is traced.
• See the entries on flattening a warped board or slab and on XY datum problems.