How To Make Almost Anything Class

Lassiter's WEEK #3 Assignment

The assignment for this week was to make a 3D object using two different machines 
and two different materials.  I chose to make an aluminum box frame with a heart shape design inside,
and with red acrylic in all the spaces  such that it looked like stained glass.  The box serves as a 
candle holder.

The materials used were aluminum and acrylic, the machines used were the OMAX waterjet cutter and 
the Universal laser cutter.
I started with an OpenOffice drawing-- made the design and then took it into the OMAX Layout.  

OpenOffice file

There were some transfer difficulties... OMAX didn't see all the lines in my OO file, and there were some other minor issues, but DiFrancesco helped sort them out. We used aluminum of 1/8th inch thickness. The file cut perfectly the first time, and the fit was just right-- except for the bottom of the box, which I needed to re-work to incorporate a slight offset caused by the thickness of the material. Otherwise it worked beautifully.

Aluminum sections made by waterjet cutter.

The difficulty came in changing machines and materials. First I cut a one to one scale of the OO file on the laser cutter, using left over refelctive acrylic for my prototyping materials. I had terrible touble transferring the OO file into the cam tool-- in general we seem to be having trouble with OO files now-- they all trasfer in with some bugs. Cam translates long smears for some of the lines in the files. Additionally, cam would not scale in the .001in range, only in the .01in range-- and I needed the more precise resolution for fitting. So I had to switch to Corel Draw and rework the files a bit in order to print/cut them on the Universal. In the end I had to use Corel Draw as my software and to print. Once I finally cut the pieces successfully--I fit all ofthe interior space pieces into the appropriate slots, and as expected, they were all too small for a good press fit.

Interior pieces.

Scaling did not work for all the pieces as one file, so I had to split the master file into many little files, one per piece, and scale each piece until I acheived a press fit-- a .02in increase in size seemed to be the best place to start, and then manipulate in the .001in range to find the perfect fit. In some cases, due to the odd edges of the pieces, I had to scale down rather than up. Once I found a fit for all of the pieces, I recut them in the transparent red acrylic for the final fitting. Unfortunately I had to start the scaling process all over again, as the reflective acrylic used for prototyping cut differently than the transparent acrylic. Ack! Another problem is that the waterjet cutter cuts a bevel edge, so the holes in the aluminum pieces aren't exactly square, which makes press fit really really difficult. Ithink John said it's about 1mil difference per 5 mils of material.

Finshed Heart Box, closeup of gaps, closeup of aluminum edge detail.

After many files and many tries, I came pretty close. If you examine the box up close you will see little gaps here and there between the acrylic and the aluminum. Each piece should probably have been slightly reworked at the edges in one of the software packages to make it perfect, but time did not permit, and I like the way this looks. Already have 3 orders in for holiday presents...