The cut list and the Check panel
These are the two panels that decide whether a design survives contact with glass. One tells you what to order; the other tells you what will fight you at the grinder. Neither will change your drawing for you.
The cut list counts the way you order
Lengths are broken down by line kind, because that is how the material is bought, and the two joining methods are counted differently for a real reason.
- Foil wraps each piece, so an interior seam is foiled on both sides and counts twice.
- Came is one channel with a piece in each side, so it counts once.
- The outside edge counts once either way.
- Guides are not in the list at all, because they are not made of anything.
The size the list is measured against is the design's real extent: the extent of its pieces, not of every corner. A line drawn past the border leaves a stub that is not glass, and counting it would overstate the panel.
Check tells you what glass will refuse to do
A general drawing tool will happily let you draw a shape that cannot be cut. Every check here names the problem, says why it bites at the bench, and suggests a fix. None of them applies one.
Sharp interior angle
- Usually
- The angle inside the piece is tight enough that the score will run past the corner when you break it.
- Fix
- Open the angle, or accept that the piece will be cut in two and joined by a seam.
Tight inside curve
- Usually
- The curve is tighter than a grinder bit can follow. Measured as a radius over a run of vertices, not per corner, so how finely you drew the curve does not change the answer.
- Fix
- Ease the curve, or split the piece at the tightest point.
Narrow neck
- Usually
- The piece is thin enough somewhere that it will snap while you foil it. Measured from the middle of each edge straight across to the far wall.
- Fix
- Widen it. Anything under about 1/4 inch (6 mm) is asking for trouble.
Line divides nothing
- Usually
- The same region is on both sides of it, so it is drawn but cuts nothing. The commonest mistake on a first pattern.
- Fix
- Extend it to meet another line, or remove it. Tidy loose lines clears them all.
Trusting it
A false alarm on a rectangle teaches people to ignore the panel, which is worse than not having one. The geometry kernel, the piece derivation and the checks are all covered by tests that run before anything ships, and the angle test does not trust a winding convention: it checks its own answer against the fact that interior angles sum to (n-2) × 180.