assignment: To construct a press-fit kit using the water laser
     and multiple materials.

     details: For this assignment I decided to build a simple, portable
     abacus using both the water laser and HeNe laser. I tried using Omax
     to develop the design but found it somewhat difficult to use. I chose
     to use Illustrator instead and aside from a few hitches importing the
     .dxf files I found it much easier to work with. 

     For my first attempt to cut the parts I used an offset of .015 inches
     for both parts. After cutting the pieces I found that they did not 
     fit together as smoothly as I had hoped. After speaking with John I recut
     the inside piece using a slightly smaller offset (.014"). Again, they
     did not snap together easily. Manu pointed out that the metal showed
     a bit of a slope through the thickness and that by filing the pieces
     just a bit I could probably get them to press fit. I felt a bit guilty 
     about this as it seemed at odds with the assignment but John assured 
     me that post-cut de-burring and filing was often necessary.

     After filing the pieces to press-fit I began to cut the abacus "beads".
     Initially I had hoped to cut thin concentric rings of acrylic of different
     color and thickness to ensure that the beads would be easy to move
     individually. It soon became clear though that the dimensions of the 
     beads were such that heating effects were distorting the final part
     shapes and I resorted to a single part bead. Upon assembly this seems
     fortuitious as the beads are easy to move singly and would likely have
     been very time consuming to assemble otherwise. Further, the effects
     of laser cutting the acrylic rendered the beads somewhat discolored
     and non-uniform which actually looks more interesting than more regular 
     shapes might have.


     

     -> .dxf rendering of traval abacus

     -> .sxd rendering of traval abacus beads