The lip: the millimetre that decides whether the lid closes.
A rigid box is made of pieces that fit into one another: base and lid, base and shell, tray and sleeve. The step that lets them fit is the lip. One millimetre too much and the lid rattles; one too little and it won't close.
What it is
The lip is the difference in size between the piece that contains and the piece contained, at the point where they meet. In a base & lid box it is the step the lid has to clear to come down over the base; in a magnetic box it is the edge of the shell the flap comes to rest against.
What it depends on
- The board thickness of the outer piece: the thicker it is, the more room is needed inside.
- The wrap paper and the turn-ins: the paper adds its own thickness on every side, and doubles up on the edges.
- The tolerance you want: a jewellery box closes on a cushion of air, a shoe box has to open with one hand.
- The box style: base & lid, three-piece, four-piece and magnetic do not behave the same way, because the pieces that fit together are different.
Why you don't copy it from the last job
Because the last job had a different board, a different paper or a different tolerance. Copying ‘the lip that works’ from one box to another is the most common way to end up remaking a sample. In magnetic boxes the base board and the shell board are often different (1.5 and 2 mm, for instance): the lip has to follow the right component.
How Cartis handles it
The lip is calculated from the chosen box style, the board thickness of each component and the paper. You only type it in if you want to change it; otherwise it is automatic, and it updates when you change a measurement or a board. In magnetic, double-flap, double-cover and handle boxes the two thicknesses are separate and the lip follows the right one.
Before you order the die, check three things: the thickness of the board you will actually use, the paper (and whether there is an inner liner paper) and the tolerance the customer expects. If any of the three changes later, so does the lip.
The guides are written by the box maker that built Cartis. If something in your practice is different, write to us: we will correct them.
See the lip on your own box.
In the demo we change board and paper in front of you: the lip updates, and so does the flat layout.