Week 7. Computer Controlled Machining
In this assignment, we will explore the world of CNC by Making Something BIG. We will learn the machine and understand its possibilities. Since I came from a background on construction industry, I am very much excited this week.
Assignment Tasks:
- Group Assignment: Lab’s safety training. Test runout, alignment, fixturing, speeds, feeds, materials, and toolpaths for your machine.
- Individual Assignment: Make Something BIG. Design, mill & assemble. Joinery without fasteners or glue will give extra credit. Also including curved surface will give extra credits.
Group Assignment
Detailed Study Report on our Group Assignment Page.
Learning Process
Learning process start from the the fundamentals of CNC machining, including the different types of machines, tools, and materials used.
Some major CNC machines are:
CNC Milling Machine
A CNC milling machine uses rotating cutting tools to remove material from a workpiece, creating a finished product with high precision and accuracy. These machines are commonly used in metalworking and woodworking.
CNC Lathe
A CNC lathe uses a spinning workpiece and a stationary cutting tool to shape and form the material. These machines are commonly used in metalworking, especially for turning cylindrical parts such as shafts and bolts.
ShopBot CNC
Our Lab has a Shopbot CNC machine. It is a brand of computer numerical control (CNC) machines that are used in woodworking, prototyping, and other manufacturing applications. ShopBot CNC machines are known for their affordability, versatility, and ease of use. One of the standout features of ShopBot CNC machines is their user-friendly software. The software allows users to create designs in a variety of popular CAD/CAM programs and then send the designs directly to the machine for cutting. The software also includes a range of features that make it easy to customize designs and adjust cutting parameters to achieve the desired results. ShopBot CNC machines are a reliable and affordable option for anyone looking to get started with CNC machining.
Unfortunately our LAB was closed due to some maintanence work and we were not able to complete our assignemnt on time. However we managed to finish our Group Assignment and which was detailed in our Group Assignment Page which is linked below.
Group Assignment
Detailed Study Report on our Group Assignment Page.
Individual Assignment
Make Something Big was the tagline for this week’s assignment. So I began brainstorming various products and eventually came up with an idea that came to me a few months ago when one of my friends came to my house with his pet “Ponnu,” a sweet little cat. We had the idea to build Ponnu a small cat house at the time. So, while I was looking for inspiration, this idea struck me, and I decided to make one right away.
The plan was to create a furniture-like product with a space for its bed and a space for its food tray. I made a design with this possibilities in mind and end up with this one.
Because I was already familiar with Sketchup, I created this concept design there before moving on to Fusion 360 to create the detailing. My biggest challenge on this design was the curvature and the joinery for that big piece with curve. So I searched and found some interesting tutorials which explains the theory behind the curvature of plywood (Link has been added in the Reference section below).
Finally I made a design like this in Fusion 360.
The plan was to make three pieces and join it together and placed on four legs with 100mm high.
a. Bottom Panel
b. Centre Panel
c. Top Panel
Unfortunately, this week our lab faced some maintenance and the wood shop was closed for few weeks, so we were unable to complete this task that week. After a few weeks, we returned to the workshop and got to work in batches.
I first did test cuts in ShopBot because I want to perform the kerf bending on plywood. I was learning more about the characteristics of plywood with each failure. And that was informative.
In Fusion 360, I created a design just for testing the kerf bending and joinery.
The pocket depth for kerf bending was set at 16 mm, meaning that the leftover 2 mm is equal to the thickness of one ply in the sheet. And made this cut in the horizontal direction of the veneer, which I believe that the right way for bending the plywood smoothly.
The milling was perfect, but the bending is so hard, feels like it will broke. Also joinery falied. By mistake I selected outside milling and inside milling wringly while setting the tool path.
Second time I milled in vertical direction of the veneer. This time I realised that the both it will work but horizontal is more smooth. I wanted to test the maximum bending strength on this part and I applied maximum pressure and it broke. But this time the joinery was perfect. Since the quality of plywood was not good it peeled of the remaining parts as well while applying pressure.
After all these test cuts and experiments, my time was running and by this time I was having a rough sketch on my final project. So as instructed by my tutor I decided to finish my project design which is convertible furniture.
Design of Convertible Furniture
The design I conceaved was very simple egg shaped side table with back side has a curved panel. Top and bottom comes with a egg shell design connected using 2 vetical panel with pocket joinery and dog bone. Th top panel is a seperate one connected to the linear actuator cyclinder comes from the gear box.
How to use Fusion 360 is explained in Week 2
3D Model for Final Project
Embedded the 3D model from Fusion 360.
Once the design is made, now we can mill everything and assemble to become a furniture. For that first we need to arrange every panels to a flat sheet and then project the sketch of that arrangement and export as dxf file.
After that we need make sure all pocket joints have dogbone so that the panels fix properly.
Dogbone Plugin for Fusion - Github Doc
Youtube Link for Dogbone Tutorial
Once the DXF file ready we can create tool path using V carve software.
Step 1: Open the V carve software and create a New file.
Step 2: Once the new file is opened, we need to mention the size of the board and thickness. Also the units and orientation if needed. By default it will the set.
Step 3: Select Import - Import Vectors for importing our dxf file from source.
Step 4: Once the dxf file is imported and placed, its time to create the tool path. Starting from drilling. In drilling tool path we can set the drill depth. Since I dont need full hole, I provided 10mm Cut Depth. This hole is for M4 screw insert.
Step 5: Next is profile toolpath. First we will set for inside cuts. For inside cut we dont need to provide tabs.
Step 6: Next is again profile path, but outside. In this case we must provide tabs, else the cut piece may slip away and chance for damaging the bit.
We can 3D simulate the toolpath and check whether everything is fine.
Step 7: Once all toolpath is defined, now we can save the toolpath.
Step 8: Now is the time for milling. Lets open the ShopbotEasy software. First we need to setup the machine. Switch on the machine and check whether the control is on. But do not switch on the spindle until everything is clear.
Step 9: We can now set Zero on every axis. First we go with Z-axis. This can be set automatic.
Video showing Z-axis setting.
Step 10: Now we can set X & Y - axis. This needs to be set manually. Use keypads to move the spindle towards the end of plywood.
Step 11: Now set X & Y - axis to zero.
Step 12: Once all axis is set now we can upload the toolpath.
Milling in Shopbot
Assembling the furniture
Back Panel we made using Zund. The grove for kerf bending is made using Zund. Because of the bed levelling of shopbot we had several issues in making groves.
This is what happened when we made grove in shopbot. So my instruct0r suggest me to use Zund.
And finally we bend the plywood.
Hero Shot
Downloads
Help Taken & References
Chat GPT used for doubt clearing and content helps.