HierarchyLeaves imply branches, branches trunks, and trunks roots

Hierarchical organization is the simplest structure for perceiving and understanding complexity.

Many woodworkers work from plans. Plans are printed onto paper, and often cut out and traced onto the wood. For non-visual woodworkers, these sorts of plans are not helpful.

Projects with clear or flowing hierarchies can be easier to remember. Think about components and how they fit together, and if it is random or if it can be mapped on to a structure that can be kept in memory. Maybe it has components that map onto a hierarchy that already parallels a mental model the student has internalized. This might be a project with a main section or “body,” parts that stick out like “arms,” and a top like a “head.” And instead of a visual diagram, have a completed version of the project side by side with an exploded version. The exploded version should let students manipulate the modular components and learn their shapes.

“A blind person has no use for printed plans”

A clear hierarchy that has clear relationships from one piece to another can be easier to commit to memory. Students can refer to the “exploded tactile plans” if they need too, but being able to construct and store a mental image of the completed object, its parts, and how they fit together is useful.

A picture of a wooden candy dispenser with visual labels of its component hierarchy. The candy dispenser is made of two main parts: a body and a jar. The Jar is made of glass, and joins the body by screwing into a lid glued to the body. The body is made of three stacked pieces, bottom, middle, top. Inside the middle is a wheel, inside the wheel is an axle pin, which is glued into a hole in the bottom of the body.

An ideal situation occurs when not only the project’s modular components have a clear hierarchy in relation to the complete project, but when their relationship to the rough lumber from which they are machined is hierarchical as well.

In the image below you can see how the hierarchical nesting of pieces minimizes the dimensions that need to be memorized. This particular example is from a project designed by Jeff Thompson of Blind Abilities Podcast. All of the project’s wooden parts can be cut from one piece of wood. It requires only a single thickness, one width measurement, one length measurement, and one hole saw diameter. Yet it produces many distinct pieces that all fit together.

A visualization of the exploded components of a wooden candy dispenser, showing the hierarchy of the pieces descending from one board in five rows.
Row 1: A large board
Row 2: Large board is cut into three equally sized boards.
Row 3: Two of those have holes sawn into them.
Row 4: All the parts are stacked, and there wheel must fit because it came from the same hierarchy
Row 5: A photograph of the assembled parts

The absolute measurements are non-critical. They do need to be reference from plans or memorized. Each piece only matters in relation to the other, but since they all descend hierarchically from the same piece, they retain many necessary dimensional aspects naturally. For example, the thickness of the wheel must be equal to the thickness of the centre part, but it always will be because it descends from the same “parent” board.

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