The offcut drawer, mapped: photograph the bed, mark the corners, cut the next job from the leftovers."
Sheet goods end their lives in an offcut drawer: half-used plywood and acrylic pieces, unlabelled, too shaped to plan around. The scrap-nesting guide turns the drawer into a material library: photograph the scrap in the machine, mark it up on a picture that maps to the real bed, and nest the next job straight onto the leftovers.
A photo has no scale until something in it declares one. The app's choice is elegant: a bank or ID card — 85.60 × 53.98 mm, the ISO/IEC 7810 ID-1 size, identical anywhere in the world. Lay the card on the scrap, take the photo, and the true scale arrives free. The same card-check sits behind the app's true-size screen for stencils and templates.
Mark the bed's four corners in the photo and a normalised direct linear transform maps photo pixels to machine coordinates. The app's tests hold it to account: a deliberately tilted synthetic photo maps back to within 0.2 mm. And the map has to earn its existence — marks are refused when they're crossed by perspective, near edge-on, too close together, or ill-conditioned, because a confident wrong map wastes a whole sheet at once.
| rule | value |
|---|---|
| the photo's resolution | 5 px/mm, capped at 2,400 px on the long side (a 300 mm bed is 1,500 px) |
| rotation snap | 15° |
| the laser's origin | front-left by default, selectable per machine |
The app states its own limits in plain words: "a photo can be off by a millimetre or two, more near the edges and with a card." The spec's target — 1 mm of accuracy over 300 mm — has not yet been measured against a real bed's photo, and the guide is straight about what that means: treat the 1 mm as the floor, not the promise. Clearances stay generous on scrap work, which is the mode where generous clearances cost nothing — and the habit pays twice, because the bed photo doubles as the record of what you already own.
Photograph the bed, nest the offcuts, cut nothing new that the drawer already holds. — the bench crew
