The cavity mold was produced in a series of 6 individual steps, as seen to the left, with a simulated machining time of 25 minutes and 17 seconds. The steps are shown and explained in the section below.

The most difficult part of creating the CAM was producing the adaptive roughing pass and the scallop finishing pass. At first, the scallop finishing finely cut the entire dome, including the flat bottom (to remove the remaining material ridges that had been left by the roughing pass). However, by tweaking the tool that was used for the adaptive pass so that it was able to cut a flat surface without leaving ridges and changing the boundary for the scallop finishing pass so it would not attempt to scallop the now-finished bottom area, we were able to produce a good finish with a decreased machining time.

The core mold was produced in a series of 9 individual steps, as seen to the left, with a simulated machining time of 10 minutes and 53 seconds. The steps are shown and explained in the section below.

The most difficult part of creating the CAM was milling the deep pocket surrounding the center island. It was difficult to fit tools down into the pocket without hitting model material, as well as to produce a polished final surface on the vertical outside and angled inside faces. Ultimately, the settled-upon approach was to utilize a pocket clearing path that leaves 0.01" of radial stock. That radial stock was removed in two 2D contour finishing passes, one on the outside wall with the 3/32" flat end mill and the other on the inside wall with the 5 degree tapered mill. This set of steps removed material quickly yet carefully and produced two polished surfaces.

The molds were machined on Monday afternoon and took three hours to complete.

Posting the G-code

The first machining difficulty was in posting the G-code to the mill. After multiple attempts, the G-code was still uploading as an empty file. This originated from the computer that was being used to post process the CAM, which was a Mac and was, for an unknown reason, unable to produce readable G-code. To fix this, the CAM was uploaded onto the shop's public computer and G-code was produced successfully from there.

Tool breakage

The second machining difficulty occurred during the third shown step in the Core CAM, where a 3/32" flat end mill clears out the surrounding circular pocket. The tool broke halfway through this operation because, after multiple passes, the team member increased the feed rate from 30% to 100%. This change was too significant and caused the tool to snap off. The learning here was to keep the feed rate low during more intense operations (like deep-cutting pockets with horizontal travel) and to pay close attention to the cut, because the team member did not realize that the tool had indeed broken until the end of the intended operation.