The edge that dented

The Lil' Duggie is a pocket-size aluminum dugout, and before it goes to a factory, the prototypes get used the way you would use one: opened, closed, carried, opened again, every day. After a few weeks of that, the edge along the seam, where the lid meets the body, started to dent. On the bare aluminum prototype it pushed the metal into a small raised lip. On the anodized one it wore a bright line through the color.

A dugout you open every day has to survive being opened every day. That is exactly what daily use is for: finding the problem before you ever hold one.

How the lid works

The Lil' Duggie has no hinge. To open it, you lift the lid off, give it a quarter turn, and set it back down across the top, where a magnet holds it out of the way. When you are done, it goes back on and the magnets pull it closed.

That magnetic snap is part of the feel, and it stays. It is also where the problem started.

What went wrong

The edge where the lid meets the body was drawn with a 0.3 mm radius. That is a very small rounding, close to a sharp corner. It makes a clean, tight seam when the lid is closed.

The trouble came when the lid was set open. It does not come down flat. It arrives tilted, and the magnet pulls it down with real force. The first thing it touched was that thin 0.3 mm edge. Then, as the lid settled onto the magnet, it rocked back and forth across that edge on each side. Every open was a small hammer blow on the least protected part of the piece. Over time, the metal moved.

The anodized prototype. The same impact has worn a bright line through the color along the seam.

The metal was softer than we asked for

There was a second cause. We had the prototype material tested. The chemistry came back as 6061, the alloy we specified. The hardness did not. 6061-T6 should measure about 60 on the Rockwell B scale. These parts read 50 to 55. The alloy was right, but it had not been heat-treated to the T6 condition we specified, so it was softer than it should have been, and the dents were worse than they would be on the right material.

Nothing in the paperwork would have caught it. That changes now. Every shop and factory we work with will supply certified 6061-T6 with a mill test report on file, a document that traces the metal to its source and states its strength. And we will pull random samples and test their hardness ourselves, rather than take the paperwork on trust.

Harder metal makes the problem smaller. It does not make it go away. The shape was still putting the impact in the wrong place, so the shape is changing too.

Designing for the way the lid lands

To fix the edge, we first had to know exactly how the lid hits it. We filmed the lid landing in super slow motion. It arrives tilted at 30 to 40 degrees before the magnet snaps it down, then rocks briefly as it settles. Our engineer laid that motion from the video over the side-view drawing, which showed exactly where on the edge the lid lands and where it rocks.

The lid landing, slowed eight times. It lands tilted, then rocks as the magnet pulls it down.

The new edge is built around those numbers. The near-sharp corner is gone. In its place, each side of the seam is a rolled shoulder, a curve shaped so a lid arriving at 30 to 40 degrees, and steeper, meets a curve the whole way down and rolls onto the magnet instead of striking a corner. Closed, the two curves meet in a fine, defined line, and the seam still reads clean.

The new seam. Each edge is a rolled curve, and the two meet in a fine line when the lid is closed.

A second version is being tested alongside it: the same seam, plus a shallow thumb scoop across the middle of each face, sized to cover the zone where the lid rocks. It gives your thumb a place to start when you open the lid, and it lets you find which way is up by feel, in a pocket, without looking.

The same seam with a shallow thumb scoop across the middle of the face.

Neither one is chosen yet. The test decides that, and so does how each one feels in the hand.

How it will be tested

The next round is four complete Lil' Duggies: two with the new seam alone, two with the seam and the scoop. Each pair has one set with N38 magnets and one with N42, a slightly stronger grade, to see whether a softer snap is easier on the edge without losing the feel.

All four are machined from certified 6061-T6 with a mill test report, and finished in clear anodize with no bead blast. That is not the final finish. It is the finish that hides nothing: any mark on the edge will show.

Then they go on a test rig: a hinged arm that swings the lid down onto its open position, again and again, following the same set of angles and drops for every piece, so the two versions are compared fairly. Each set has to be opened 1,000 times, with a check partway through and another at the end.

When the results are in, they will be posted here, with photographs of the edges.

A seam is a small thing. It is also the part you touch every time you open it.

— None Better