7.Computer controlled machining¶
Overview¶
This week was all about learning Aspire, our labs ShopBot, and wood working with joints and sanding
Group Work¶
Our group assignment for this week was to complete our lab’s safety training and test runout, alignment, speeds, feeds, materials and tool paths for our machine. Click here to go to the site. My group this week was the boys boys boys Fab Academy: Andrew Puky, Noah Smith, Cooper Cumbus, and Wilson Zheng. I was chosen as the group leader which meant I was in charge of assigning tasks to every person, helping out in all areas of the design, and taking the blame if we broke anything. But I specifically helped Cooper out in the runoff testing. For runoff testing, we measured the accuracy of our cutting tools as they spin. I used a runoff tester to figure out how much adjustment was needed when cutting, as the measurements we in the design files alone are not always precise. We tested 2 different specific bits that we used the most. This includes the 3/8” compression bit on the large ShopBot and a 1/4” bit on the smaller shop bot. We found that there was a consistent variation of 5 thousandths of an inch. This small adjustment with the offset helped us make our cuts much more precise and improved the quality of our projects.
Fusion/Aspire¶
Overview¶
In Aspire I had to create a piece of wooden furniture or something similar that used press fit joints and used more than 1 meter volume of ply wood, either 1/2 inches or 3/4 inches.
Process¶
I decided to create a stool for my project, however I encountered some problems along the way that hindered the final result’s effectiveness. A. Step one was to look a previous documentation for ideas on how to create my project. Specifically Ginny Foster.
B. Next the goal was (in Fusion 360) to create the general design for the project aka how I wanted it to look. I decided to create two legs that fit into each other with one top holder to keep the legs together and provide an adequate place to put stuff.
C. I had to be sure to create a parametric value of the thickness of the desired wood. I decided to use 1/2 wood which was a mistake that I will talk about later. So any openings that relied upon the thickness of the wood would remain the same no matter the size of all the other pieces of the design.
D. After creating a working model in Fusion 360 I had to move the design into Aspire to help create the files for the ShopBot milling machine. I exported the Fusion files as a DXF file which I could then import into Aspire.
E. In Aspire, specifically material setup, it is very important to choose cut from machine bed not material surface, remove any offsets at all, and put the correct dimensions for the machine bed. The reasons for these changes are to ensure that the shope bot cuts exactly where I want it to cut, in the correct x, y, and z positions.
F. After importing the the DXF file I removed any unnecessary lines that Fusion might have accidentally sent out, like dimensions lines or construction lines.
G. Finally I had to add the dog-bone bit to the design so that the pieces of wood could fit together correctly. Unfortunately the tool I was using (3/8s compression spiral bit) was too big to create the bit in my design, so I had to use the T-Bone bit instead which is why they are a thing, when the bog-bone is too small.
H. Finally I had to create the tool paths for all 3 pieces of wood. This was a pretty complex process with lots of tiny steps so pay extra attention. First I needed to make my cut depth 0.005 inches greater than the material so I could cut through the wood entirely. Then I selected 3/8” compression Spiral bit as my bit for the tool path. I had it do 2 passes to ensure a clean cut. I added 4 tabs to each piece of the design to ensure stability whilst cutting. I added ramps for smoother movements on the machine. And then I had my cut.
ShopBot Milling¶
Overview¶
The Desktop Max Shopbot Cutting in the Charlotte latin lab is a machine that can be dangerous but only if it is not treated with respect. Be sure to follow ALL rules when learning how to use it, and follow the darn workflow.
Process¶
A. Pull up the Latin ShopBot workflow on the Fab gmail account. It will specifically walk you through how to cut out wood using Aspire. Find it here
B. First, I needed to open the Aspire file on the computer that should be connected to the CNC Shopbot machine.
C. Then, we needed to hold the wood down to the machine using plastic brads. Bradding the wood down to the wooden bottom make sure that the wood will still stay in the same position, preventing any errors while cutting.
D. Next, I had to do an air cut to make sure that the cut would not break the machine. I also had to change the machine bit to the 3/8” compression spiral bit since that is the one I chose to use.
E. Now it was time to cut out my plantar. I clicked start and watched the CNC machine very carefully for any problems at all. Luckily all my preparations had resulted in a good cut.
F. Once finished, I vacuumed the wood dust.
G. I had to use the crowbar to remove my pieces carefully using a motorized small saw. I specifically used the motor to remove the tabs I put in place.
H. Next I needed to actually assemble my design. First I placed the legs on top of each other then tried placing the top counter in its spot. However the problem with this plan was that I did not account for how tight the wood would be on all four sides. I should have given more clearance to allow a better press fit. To fix this I decided to and sand down any extra large pieces and to wedge it together.
Hero Shot:
