Laser Cutter - A PressFit Shark

Concept

Assemble a 3D model (a hammerhead shark) as a series of 2D panels.

Background

I wanted to try using some pre-production software from Autodesk for automatic decomposition of an arbitrary 3D model into 2D slices.

Full Disclosure: This software was acquired from a company founded by MIT graduates Saul Griffith and Jack Bacharach. Some of the ideas were partly developed during their time at the Media Lab and at the CBA.

The Software

The software is designed to open a 3D model (STL or OBJ) and allow the user to specify stock parameters, kerf etc. The software then "slices" the model into a series of 2D panels - either on one axis or on two. One axis slicing produces panels that can be glued together. Two axis slicing produces a waffle layout with notches where the panels can be inserted into each other.

The STL file (a triangular mesh) and the proposed slices rendered in 3D

The software will then layout the panels on a 2D sheet. This output is EPS. In addition to the cuts, text is rendered on the cardboard that describes the part number that should fit into the slot. The cuts and text are rendered as two different colors.

A detail of the EPS file, each notch has the part number that should be inserted.

The Laser Cutter

The EPS file was loaded into Corel Draw which has printer drivers for the laser cutter. The text was imported as red and the cuts as blue. All of the geometry needed to be selected and converted to "hair line" (to convert to vector output). The feed speeds and power were then set per color. Nice!

The laser cutter and a short movie of the shark body being cut

Results

I was impressed with the text as rendered on the cardboard. It scaled nicely to many different sizes. The notches fit snuggly.

The shark during assembly and a detail of the very fragile tail.

There were some parts that had notches that were too small to utilize. These parts fell off.
The notches made for part 13 destabilized these parts. They were longer than necessary.

Enhancements

Notches
The notches going half way through the part was difficult to work with for the bigger pieces. The density of slices can be reduced where the notches are long. The notches need chamfers for auto alignment. I am curious if a chamfer that runs the entire length of the notch is better than a short chamfer at the end of the notch.

Some analysis (optimization) to pick the best slice direction (the one that creates the maximum number of sound parts and connected components).

Future things to Try

With more laser cutter time, I would like to try a few more models. The elephant is calling my name.

I wonder if I could make a "skin" for the model by shrink wrapping. I am thinking vacuum melt some plastic bags on the model.