Week 7. Computer Controlled Machining - Noah, Andrew, Tyler, Cooper, Wilson¶

This weeks assignment was to

do your lab's safety training
test runout, alignment, fixturing, speeds, feeds, materials,
and toolpath for your machine

Our Files ¶

Work Distribution¶

Cooper: Runoff testing, Runoff documentation
Andrew: Thickness gauge, documentation
Noah: Runoff testing, Materials documentation, Safety documentation, Fixturing Documentation
Tyler: Runoff testing
Wilson: Thickness gauge, documentation

Safety Training¶

Before we even touched the shopbot, we watched the lecture for this week and received a detailed safety training from our local instructor, David Taylor. He went over all safety involved with operating our machine. The main resources he used were from this google site and this workflow. When going to mill, we would follow the workflow exactly, as it described everything required for setting up the machine and software, aswell as useful troubleshooting tips. Our shopbot also has useful add-ons. The two ones that keep us most safe is colored grip tape on the floor to tell us where its actually safe to stand, and a spindle power interlock that allows us to disconnect the spindle (bit rotating motor) from any way that it could be powered

Materials¶

We have 2 different “classes” of milling machines at our lab, we have the big ones with the small shopbot (2’x4’) and the large shopbot(4’x8’) and the smaller bantam tools milling machines.

Materials that we cut on our larger machines¶

-Wood (oak, walnut)
-Plywood 
-Softwoods (pine, cedar)
-Foams

The shopbot can also cut alot more than this, but we just don’t use those materials in our lab.

-MDF
-Acrylic
-Plastics
-Metals

Of course, every different material requires different feeds, speeds, bits. Some even require dust collection due to the harmful nature of their chips to humans or the cut.

Fixturing¶

In order to cut wood (and another materials) safely, we had to secure it to the shopbot. Last year, as part of our engineering class, we made cutting boards. For holding that in place, we used a jig with clamps in the corner, then avoided cutting near these clamps. In order to cut bigger wood, like the 48x96 inch wood sheets we used for all of our projects this week, we couldn’t use a jig. Instead, we used brads. Specifically, plastic brads shot in through a nail gun. These are essentially nails, but without the destruction that comes when a bit runs into them, as they are made to be easily cut by a router.

Runoff¶

To test runoff we used a runoff tester on several bits to find out how much more depth was needed when cutting a board since measuring to board isn’t enough sometimes since the tools are never exact. To figure out how much room was needed we tested the spin of three different bits while measuring them with the runoff tester. We tested the 3/8ths on the big shop bot and the 1/4th on the small one. In both tests we found that the meter moved to 5 thousandths of an inch. This was later applied when cutting out our designs since we knew that their was a small margin that needed to be added.

Thickness Gauge¶

Mr. Dubick wanted us to create a standardized thickness gauge for the lab after learning from ShopBot representatives that this method of measuring board thickness was highly effective. Previously, our designs varied significantly in size and shape, so he aimed for consistency.

We used Aspire to design the gauge and generate toolpaths, incorporating gaps that gradually increased in size. To ensure the drill bit could reach the interior corners, we added dogbones. We also engraved text to indicate the size of each gap.

1/2" Wood settings 3/4" Wood settings

Next, we generated the CNC toolpaths, adding tabs to prevent the parts from shifting or flying off during cutting. Additionally, we programmed the bit to ramp into the material rather than drill straight down, which helped extend the bit’s lifespan and maintain lower temperatures.

1/2" Wood settings 3/4" Wood settings