6. Large format CNC (computer controlled Machining)¶
This week’s tasks:
a) Learn how to use the CNC machine
b) Design something and cut using the machine
CNC Machine¶
A CNC (Computer Numerical Control) machine is a manufacturing tool that uses computerized systems to control the movement of cutting tools or machinery. It operates based on instructions from a computer program, allowing for precise and automated manufacturing processes.
We noted down the specs of the machine, safety precautions as well as conducted a test that you can find in the group assignment [here.] (https://fablabbh.fabcloud.io/asterisk/2024/batch11/Group%20work/cncA/)
Individual assignment¶
After familiarizing myself with how the machine works, we were asked to “build” something using either a 12mm plywood or MDF board. First, we have to setup the workspace by securing the wood material you will use.
So I decided to make a short stool that my mother requested to make. I had made several attempts until I achieved a design that was able to cut and fit together.
Design 1¶
The first stool design i made was inspired by a 3-legged stool i found on pinterest. The first thing I did was make the measurements of it on AutoCAD.
INSERT AUTOCAD PIC-DIMENSION
I then brought my 2d design to Fusion to model it and see if the dimensions are proper for a stool. This is my first time working with “parameters” which I realized is a very important thing when it comes to modelling anything especially designs that require to be a specific dimension. By setting parameters, you are able to modify without altering every part of your model.
Here for example, I set a parameter for the thickness of the wood to be 12mm so that if I do any change to the design such as scaling it up or down, the thickness of the wood remanis the same.
I mainly worked with mirroring in fusion. So I designed half the profile of the leg and mirrored it then copied the same design for the other 2 legs.
For all the pieces, I made an extrusion of “wood” using its parameter that i set to 12.
Here, I used another parameter which is the stool height to be a specific height. So that when I do decide to change the height, I can simply change it in the parameters.
Then I rotated the leg to a certain angle as to how it would stand which was hard to figure out so I just eye-balled it.
Nevertheless, I laid the drawing flat to get it ready for exporting.
But first, to make sure the pieces fit together, we used the laser cutter to cut a mini version of it to serve as a test.
The material used for this is plastic which is a much thinner material than the wood that will actually be used for the final product. And the joints were able to fit together,though tight.
After modelling the stool on Fusion and testing it, I separated each piece which comprise of the 3 legs, the seat itself and a support that will be attached in the center to keep them all in tact. To start, we have to lay the material which I will be using that is MDF wood and securing it to the board using nails.
Once the design is ready, import the file as a dxf into VCarve Pro to input the settings to make it ready for cutting. Now I’m ready to cut it on the CNC. The size of the canvas is the size of the wood we’ll be working with, so we try to maximize the space.
It mentions that it will start printing using which tool and what material thickness
upon gathering all the pieces, we tried to assemble them. The two legs of the stool fit perfectly, but it was tricky to connect the third leg due to the angle and the rigidity and thickness of the wood.
After several tries and trying to make the third leg connect with the 2, unfortunately, it ended up breaking.
Design 2¶
Because I faced a lot of issues fitting the joints in the first stool design and lack of time, I had a back-up design that was much simpler and easier to fit together. I made the model using this youtube tutorial to make a quick design to cut.
The stool comprises of only 3 parts; the legs that interlock together and the seat that goes on top. After making the circular seat, you sketch on the front plane half of the leg to mirror to the other side. These are the dimension I used
For this design, I also worked with parameters. You can notice how the dimension can refer to the parameter plus an equation. In this case, wood thickness/2 since it will extrude both ways from the z axis
After making the first leg, I copied and rotated it to make the other leg
Now, we edit the profile of the legs to make the slots that will be the joints. These are all the parameters I used
To make the slot on top of the seat, I used the radial tool to create however many of the sketches I made. In this case, 4 with these measurements
In order for the joints to be able to fit more easily, I created a dogbone fillet for the inside of the slots
I gave the stool inner edge a fillet so it doesn’t look very harsh.
Now that all the parts are ready, I once again lay them flat and exported each as a dxf to send it to the machine to cut
I realized, it was easier to apply dog-bone fillets in Vcarve itself as it has built-in option to choose an edge to transform. So i went ahead and did that for all inner edges
Then we do the usual step of arranging the pieces onto the board. This time I will be using plywood to have a more wood-y finish than MDF
Process of cutting
Joining them together
Finishes¶
Sanding it down using sandpaper
Here is how it looks all put together
I decided to give it some color by using a wood stain.
This is the stain I used which I highly recommed. It has a very nice undertone and is definitely buildable
I tried to stain the pieces all at once so they all dry together. I’d like to give a special thanks to my friend Fatima for helping me out in this long process. I then left it to dry for over 24 hours
I think the stool turned out pretty neat after staining it rather than its bare finish