Semicolon Trophy

April 2018

Acrylic 

 8" x 6" x 3"

This trophy was a light hearted 'award'  commissioned by Vincent Zeng.  For the  Assistant Dean of Outreach in the School of Computer Science at Carnegie Mellon University. It is made from 1-3/4" acrylic disk that was milled on an CNC router, polished to a high gloss and then the text was laser engraved. The base involved more traditional wood working techniques.

My client and I worked through a number of concepts and eventually settled on a chintzy design that resembled a participation trophy.

Because this was milled out of a disc of acrylic this simple mockup made in Adobe Illustrator helped to maximized the stock we were using. It also allowed me to confirm with the client the text and the layout of the final piece. 

A 3D model of the final part was constructed that included a circular jig to act as registration and work holding to ensure that the round part did not shift during milling.

Toolpaths were generated in Fusion360's CAM suite consisting of a roughing pass with a flat end mill to clear the bulk of the material, and then a faster finish pass with the same endmill to improve the surface finish. A contouring pass was then taken to free the part from the remaining stock.

Here is the part on the router table inside the work-holding jig. The entire job took ~45 minutes due to reduced feed and speed rates in order to allow for a better surface finish.

After the part came off the table it was sanded and polished with an abrasive plastics polishing compound to get the faces and edges back to perfectly clear. 

The final step in the process was to laser-etch the text. Another jig was cut to properly register the part in the laser cutter and the laser settings were fine tuned on some of the off-cuts from the acrylic milling. 

 

Ethan Gladding