PlywoodSheetArraying

The following diagram represents an attempt to arrange pieces of the plywood rib on to raw sheet stock. This set of images explores the arrangement of raw sheets, sticking to a method of orthogonal rotation. Each image contains a data set containing the amount of sheets needed as well as the cost. The goal of this taxonomy is not to choose the most economic system, but rather to study the relationship between pieces, arrangement, effect, and cost.

This study examines two different plywood sheet sizes. The first is a 4 'x 8' sheet that is common among most types of plywood, including marine grade fir, exterior grade fir, and Appleply, all of which are being considered for this project. The second is a 5' x 5' sheet, which is the standard sheet size for Baltic and Finnish Birch plywood. These types of plywood are know as 'multiply', which means that they contain more plys per given thickness than a comparable sheet of 'regular' plywood. These thinner plys are also of higher quality, and are free of gaps and voids, yielding a much more stable panel. Both Finnish and Baltic Birch are products of Scandinavia.

Both types of panels are being studied due to questions of availability and durability.

• Finnish Birch is most desirable due to its solid construction and use of Type I phenolic glues, which are water resistant. Sheet size = 5 x 5
  
• Baltic Birch is very similar in composition, and although it can use Type I glue, it often uses a Type II non-phenolic glue, which doesn.t hold up to moisture as well. Sheet size = 5 x 5
• Appleply is also a multiply product that is made America. It is unknown as to what type of glue is used. Sheet size = 4 x 8
  
• Marine grade fir is softwood plywood that is made with gap free treated plys and Type I glue. It is very strong and water resistant. It is often used in small boat construction.
• Exterior Grade fir is a softwood plywood that uses Type I glues. Rated either exposure I or exterior, it will hold up fairly against the elements but is often not very stable.

The machining of the ribs will be done with either a laser cutter or a cnc router. It is desirable to have flat sheet stock for both machines. The cnc router available has a deck size of 6' x 12' and can handle any type of wood. The laser cutter has a deck size of 4' x 8' but, the fabricator prefers using Baltic Birch because of its superior machining ability. The default birch sheet stock doesn't fit in the machine. This exercise explores different possibles of pre-cutting raw sheet stock in order to find an effective method of which to array them.

This second set of images looks at the possibility of cutting the raw sheet stock into many smaller pieces and arraying them tangentially along the curve of the rib. In this manner, the grain of plywood will actually 'grow' along the length of the rib. Additionally, this grain will function in a manner that is in line with its structural capabilities, spanning continuously parallel between supports. An area of special interest is the connection between the individual pieces. With the iterations on the left, the pieces were array 3' on center. Doing so yielded interesting, non-uniform overlaps. One iteration was chosen for a manual arraying process, in which pieces were placed with minimal overlap. Material reduction was 2 sheets. These overlapping zones have the opportunity to become specialized joints, as a byproduct of material normally considered to be waste.

The next step will be to analyze the relationship of the number and arrangement of pieces to possibilities in sub-structure self joining, primary structure connections, and cost.