Computer Controlled Machining

Introduction

In this week we are required to make something big. I was so exited for this week because I took a course about manufacturing during my bachelors degree but due to the time we weren’t able to make any furniture on the lab so now in the Fabacademy I have a chance to do what ever I wasn’t able to do it during university. Firstly I was planning to make a floor shelf, I got this idea when I was browsing painterset website and I notice a shelf made by recycling wood that utilize iron connection. So, I asked myself what if I can do it fully by wood without using any screws. The first step was sketching the design then convert it to digital copy by using Fusion 360. But Again due to covid-19 and the lack of time I changed my plan and decided to make my final project design instead which is a tray table.

Group Assignment

The link if the group assignment can be found here

What I am required to do?

• Document how I design the object

• Document how I made the CAD-toolpath

• Document how I made something big (setting up the machine, using fixings, testing joints, adjusting feeds and speed, depth of cuts, etc..)

• Describe the problems that I faced and how I fixed them

Softwares I used

• Fusion 360 for the 3D design

• VCarve Software to be able to get the g-code format for the CNC ShopBot

Machines I used

• Universal Laser Machine (PSL6MW) to test the design if its fit or not using the cardboard and mdf

• ShopBot

First Design

As I mentioned in the introduction I made a floor shelf design and I tested it using the cardboard and mdf. I am going to show my attempts to make the design fit.

• Firstly I made a design using fusion 360 which is as shown in the picture below

• Then I used the laser cutting machine to cut the design and this was the result with the cardboard. The result is really good and it look as what I expected to be but when I showed it to our instructor he told me to try the mdf instead of cardboard because the cardboard is flexible but the mdf is not. and the mdf is similar to the wood that we are going to use on the ShopBot

• When I tried the mdf the result was bad I wasn’t able to insert all the shelfs. It was like I am fighting with the shelfs as you can see below

• Then I made some modification for my design on fusion then I cutted the design again. and the was the result

The design was not good I don’t really like it. I was not satisfied with it. so I was planning to make some modification to the design but as I said due to the lack of time I changed my plan and decide to make the tray table design for my final project.

Second Design

The second design that I made is my final project design (tray table). I made the 2D design using Fusion 360. I tried to made a simple and beautiful design that will satisfy me so I browsed Pinterest again to see examples of a modern table and take my inspiration from them. Below is the 2D sketch of my design.

• I used the laser cutting machine to test my design and checks if the parts are fits to each other.

Third Design:

There were some modifications on my table design (Second Design). I didn’t test the design using the Laser cutter machine this time because I already did the test for the previous design which I think is enough to make sure that the pieces are fits to each other because the third design is a modified version from the second design.

• Clearance testing for CNC

Now the real work is started. The details of what I used is listed below:

1. 18 mm wood

2. Tool diameter (Milling bit) = 6mm

3. Metal Plate used for Zeroing the z-axis

4. Caliper to check the Wood Sheet Thickness = 17.90

Machine Setup:

The machine used for this assignment is ShopBot. The machine axis must be set to zero before cutting.

1. Zeroing X/Y Axis: This CNC machine required zeroing X/Y axis.

2. X/Y axis zeroed: X and Y axis have 0mm values, this confirms the zeroing of those axis have been successful.

3. Checking the Milling Bit from Both Sides: Physically confirming the zeroed axis.

4. Zeroing Z-Axis: To zero the z-axis, the process is different and it requires a clip and a metal plate. The Clip must be connected to a metal part of the machine. The metal part which must be positioned under the milling bit. Once the process of zeroing z-axis is started, the milling bit is slowly moved towards the metal part until it touches it. This way the z-axis is zeroed.

Vcarve Settings

1. Specifying Wood Sheet’s Dimensions: The job size is made to match the wood sheet’s dimension of 2440 mm x 1220 mm

2. Wood Sheet Must Be Fixed Using Screw: Circles appropriate to the dimension of the screw must be added all over the sheet of wood on VCarve software. The pathway must then be saved and executed, once the CNC completes milling those holes, then with a drill a screw can be placed on each hole to fix the wood sheet on the CNC machine.

3. Toolpath: The setup for drilling toolpath for all the circles around the sheets which would be screwed using a screw driver. The depth of cutting will be 18.2mm.

4. Choosing The tool: The tool I used is End Mill 6mm

5. Saving Drill Pathway

6. Screw Placed On the Sheet

7. 2D CNC Machine’s Milling Bit Limitation: Require Dog Bone Fillet for Inside Cutting: CNC machines have limitations when it comes to inside cutting on a 90 degrees pathway. The solution is to use 'Dog-Bone' fillet.

8. Cutting Path and 3D View I had to use two wood sheet due to the big size of my table.

• The below video shows how I make the toolpath for the outside parts:

• The below video shows how I make the toolpath for the inside parts:

9. Do Not Forget To Add Tabs As Well: to Prevent Pieces From Flying these tabs secure each object and prevents them from moving out of their place during the milling process.

10. Press “Cut” and Loading Cut Path Files then Press “Start”

11. Do Not CLICK OK Before STARTING the Spindle!

12. Turn ON spindle

13. Press “Green” Start Button

14. Cutting In Process

15. Removing the Taps from the parts

16. Sand Paper Tool To Smoothen Edges

17. Joining Parts Using Rubber Hammer

18. Final Result

19. This is the picture of the final project table after finishing everything

Problem I faced

This week I had many problems. I will list them below.

• The first problem is that I forgot to remove the screws pathway when I started the operation so what happened is that when the machine started working it went directly to the screw so the milling bit got broken.

• The second problem is that the taps I added were very thin so when I started the operation one of the pieces went to the air so again the milling bit got broken. so I had to add more taps and make sure that the parts will not move.

• The third problem is I didn’t clicked on start button after finishing the first part of the operation so again the milling bit got broken for the third time.

My Files

CAD Design

table toolpath

table toolpath - part 2