( h o w . t o . m a k e ) a press-fit construction kit

gershon dublon
responsive environments group :: MIT media lab

the press-fit lampshade

This week's assignment was to make a press-fit construction kit using the universal lasercutter. I went through several ideas for kits before arriving at the lampshade design, including interchangeable style glasses frames and planter boxes. Elements from both appear in the lampshade.

As expected, a good deal of time went into figuring out the best press-fit slot size. The laser has a kerf of 0.01'', which has to be taken into account for a good fit. Since I did my design in Adobe Illustrator, I factored in the offset manually. The cardboard was 3/8 of an inch thick, but some compression is important for snugness. Fortunately, some testing was done for the class in advance, so I had a small range of sizes to start with. Knowing that I would need a slot size in the vicinity of 0.154-0.158 inches wide, I increased the size from the minimum until the fit was just right. Since the laser cuts down the middle of the line, the slot is 0.05 inches out of the line on each side. Ultimately, the slots as drawn were 0.148 inches -- 0.158 inches with the kerf.

Next, I came up against some interesting properties of corrugated cardboard. I found that cutting against the corrugation results in weak, threadlike strands (a nice effect, but not so great for staying together), while cutting with the corrugation results in far more structurally-sound links. Both styles were incorporated into the design. The orientation of the cut was particularly imortant because many of the panels had dense textures that required removing a lot of material.

It took a long time to print some of the more detalied textures like the shape patterns and the turtles. All the textures were vector drawings, assuring that the laser would cut all the way through the material (thus letting the most light through).

After printing and constructing the outer surface of the lampshade, I designed the mechanism for attaching the lampshade to a working lamp (it hangs from strings tied to snap-on hooks) and I added some hanging pendants for decoration.

mas863 2009