I've really enjoyed these courses, and I've learned a lot about operating the vertical mill as well as the horizontal mill (lathe). The courses are very hands on and we spent a lot of time operating the machines, measuring tools, measuring fixture locations, and cutting parts. I've particularly enjoyed learning much more detail about G-Code.
The WCC Industrial Technology building is well equipped. They have four Haas vertical mills and three Haas horizontal mills. And quite a few robots - I previously took ROB 101 and ROB 110. But that's another post... Here are some pictures of the machine available:
During NCT 101 we cut six aluminum parts, three on the lathe and three at the mill. These are (L-R): Andy's Cube, Stanley Cup, Bongo Bat, Chess Pawn, Turner's Cube, and Red Wing Keytag.
We made four of each part, one to turn in and one for each of our group members. After the cut the first part we measure it for accuracy and make any adjustments in the wear registers of the tooling or work offset register of the part. We document this in some paper work to practice logging the machine and tooling setup.
The final project in NCT 101 is to take a logo of our choice downloaded from the web and get it set to cut on the mill.
Most of the class projected the logo over graph paper and measured XY coordinates. These were stored in a text file which gets imported into an Excel spreadsheet which does some scaling and offsetting of the coordinates. Then the extra G-Code is added to build up a program. That's not quite my style so I ran the logo through Adobe Illustrator, auto-traced the edges and generated a vector file I could import into Rhino. I then wrote some Rhino Python code to step along the curves at the specified resolution and write the G-Code automatically. Much easier :)
If you're curious you can download the code here: CurvesToGCode.py. Note that the code output is particular for the Haas vertical mill but could easily be adapted to other machines.
First we tested the code using NCEdit, a program which is part of SurfCAM. It lets you draw motion of the mill on the computer screen so you can see if it's going to cut correctly. Once you get that right you can load a pencil or Sharpie into the mill and draw your logo on paper for a second verification.
With that complete you're finally ready to cut. Here's the mill I used - ready to go.
The logo was cut on a 12" x 12" piece of 1/4" clear cast acrylic.
The tool was actually a center drill. Oddly, its geometry works well for milling acrylic.
The spindle was set at 7500. The feed was 20. The depth of cut was a mere 0.005" per pass. I cut it in three passes.
Here's the result with the protective paper removed and flash photography to illuminate the edges: