Introduction: LINEA Waterjet Studies
Materials come together all around us; on the furniture we sit in, in the products we use, and within the spaces we inhabit - interacting by way of joints, overlaps, reveals and so forth. In their simplest form, these intersections are revealed as single lines. These studies use the interface, between two parts of a single material (in this case 3/16” hot rolled steel plate), as a locus for various expressions of a single line ‘joint’. Modulations in the line (stitching, zig-zagging, etc.) give assorted functionality to the parts - from a sliding to ‘latching’ to interlocking. By adding multiple layers, additional fastening options become possible.
The LINEA Studies are not meant to be practical solutions to any perceived problem, but rather speculations on the relationship between expression and functionality of the ‘joint’.
3/16” hot rolled steel plate
Drill press / countersinks
Step 1: PROCESS
Before designing the joints themselves it was necessary to run several tests with the waterjet to find the optimal offset between the theoretical edge and the actual edge after cutting ( a number of factors can contribute to the difference in the two - the nominal nozzle dimension/kefr vs. the actual, the speed/quality of the cut, the flow of the garnet, and the limitations/accuracy of the machine itself). Edges were offset into each piece from the centerline by .001”. This was done five times at .001” each time resulting in gaps of .002”, .004”, .006”, .008” and .010”. At a middle range cut quality (a balance between quality and speed) .010” was found to fit the pieces together without any manual filing or cleanup.
Once the offsets were found, then the samples could be designed and cut. Several types were designed to explore different methods to join the pieces:
Step 2: Puzzle-piece Type Joints
A. Simple sliding joints, where piece could mate by pushing together unobstructed in one axis perpendicular to the edge.
B. A variation on the sliding piece simply rotates the sliding vector so the pieces slide together at an oblique angle.
C.Yet another ‘sliding’ connection ‘hooks’ one piece into another allowing for a hanging type of assembly.
D. Another type locked together in a ‘puzzle-piece’ manner so sliding wouldn’t be an option.
With any of these variations, by adding a backing plate and welding to one piece, a mechanical fastener is used to fix the ‘loose’ piece in place (the bottom backing plate is tapped and the top piece is countersunk for a flat head cap screw). Fit is self-registering with the ‘puzzle-piece’ nature of the connection making assembly of a joint an intuitive process
E. A more 3-dimensional joint type used a single flat-head cap screw to ‘lock’ all the pieces together - 2 puzzle-piece top plates pushed apart into tension by the fasteners bevel and a perpendicular piece tying the assembly together with ‘tenons’.
Step 3: Zipper Joint
Lastly, a ‘zipper’ joint was explored through the use of a parametric script to control variables of the joint. Countless variations are possible with this system - from seams between co-planar pieces to box-joint type connections between perpendicular planes.
Step 4: Prototype
The previous types were designed as ‘generic’ joints with no specific application intended, though one can imagine a range of possibilities - from tabletop surfaces to demountable hanging systems to interlocking joints of flat pack furniture. Scaled up and the joints could become more architectural.
As an exercise to test some of these ideas, a hypothetical three-dimensional joint (corner) condition was designed. An interlocking plate assembly was welded between two upper struts while a vertical ‘leg’ fit into a hole (and was welded) on one of those pieces creating a complete corner. A bottom plate with a hole pattern matching that of the ‘removable’ strut was welded beneath the opposing assembly. It was tapped to receive two fasteners, which hold the removable piece in place. All welds on the top/outer surfaces were ground flush to give the tubes and plate a monolithic aesthetic. The steel was subsequently given a black patina.
Step 5: Conclusions / Speculations
This was a very simple and quick exercise and only the beginning of possibly many more variations and types. All of these tests were done with simple 2D cutting while the Omax waterjet at Pier 9 is capable of 5-axis cutting, making many new types of 3D joints possible. I developed some of this potential in the joints of the Oblique Tenon Stools, but would like to further experiment with these techniques.