Joining small lumber together into bigger boards is common practice in woodworking, however joining smaller scraps of plywood together is quite uncommon. This is because you need to match edge grain to edge grain, rather than weak endgraing to endgrain. In plywood is composed of alternating sheets of wood which go in different directions half endgrain, and so you are connecting ½ engrain to ½ engrain. In this exercise, I show one method to increase the surface area of the gluing to create more contact between the edges of plywood and therefore a better bond.

My principal consideration for the sine curve was minimize the amplitude an (to minimize the amount of waste material) yet still allow the end mill to fit into the gap of the curve. I chose to use a compression endmill, specialized to cut plywood – it cuts down at the top and up at the bottom minimizing the material tear. The MIT woodshop has one compression endmill – 3/8 inch – and so therefore, this was my endmill choice.

curvature analysis to see if the endmill will cut out all of the shape (Important for teselation).

Speedy Production

The cut file was very simple - Just one sine curve set up on the y axis. I swaped in different pieces of wood to the milling corner, milled it, and then swapped in the next piece. The whole process was quite fast, and allowed many different sized pieces to be milled with the same cut pattern. The limitation here is that only large pieces of wood can hold enough suction to be firm against the endmill. An extension of this exercise would be a spring-loaded vacuum suction device could fix smaller elements to the bed.

Speedy Production

The sine curve also allows for a fast milling path that does not need to decelerate or stop.

Daniel Marshall 2017.