Week 7

Computer Controlled Machining

10/15/2025-10/22/2025

Group Assignment

Here's the link to our group assignment: group assignment

For the group assignment, we checked the margin/kerf for the CNC machine.

Ideas

I want to build a chair/sofa for my dorm room. Currently, I can only sit in my chair or my bed to do work, but it would be nice if I have a nice cozy sofa to relax and do some work in. Getting a good quality sofa is expensive, and especially some of the nicer ones with more features. For example, a zero gravity chair that allows reclining stands at around $2,000.

It is very enticing to build something for myself so I have a personal space to sit and relax in.

I also created some sketches to get a better feel of how the sofa will be laid out.

Ideas

I want to build a chair/sofa for my dorm room. Currently, I can only sit in my chair or my bed to do work, but it would be nice if I have a nice cozy sofa to relax and do some work in. Getting a good quality sofa is expensive, and especially some of the nicer ones with more features. For example, a zero gravity chair that allows reclining stands at around $2,000.

It is very enticing to build something for myself so I have a personal space to sit and relax in.

I also created some sketches to get a better feel of how the sofa will be laid out.

3D Model

I started 3D modeling by visualizing what my bench would look like and developing all my parts on one plane. This is a little challenging and unorganized as I constantly needed to check where each part goes and which part is still missing.

I also realized that my first design would not fit on the 4ft by 8ft stock provided. I definitely was a little ambitious in wanting to build a full sofa with good support for my seating position. Realizing that all of my parts together won't fit in the stock, I needed a smaller design

Later, I learned from Ceci that it is better to assemble all my parts before arranging them on the stock. Since I didn't model anything too complex in the earlier weeks, I need to learn how to use joint in Fusion 360 to assemble all of my parts. I also modified my design to use less parts. For example, I reduced the height of the back holster so the back support mostly holds the lower back of the body, compared to before where I had my back support trying to go higher to support my upper back and head. In addition, I reduced some materials from the side frame, changing it from a full enclosed design to a H-shaped design to open up more space for me to place connecting parts during the cut in these extra spaces. My new design takes inspiration from a previous project built by Alice Nasto.

This time, I designed all my parts and assembled them using the Fusion joint feature. I then used arrange feature to easily lay all of my components on a rectangular solid with the same dimension of the stock, which is 96 inches by 48 inches.

I also realized that I forgot to add dogbone to my inner cuts. I used the add-ins to do it but it doesn't work for all of my components. So I had to manually add the circles with radius of 0.25 inches. Ceci also told me to add straight lines tangent to the circle so it allows the endmill to enter and create the dogbone.

CNC Machining

When I started my first cut, I quickly realized that the milling machine is going in the wrong direction. It was actually moving outside of the cut area. I went back to check my manufacturing setup in Fusion and discovered that my x & y axis were pointing in the opposite direction of the stock. After consulting Ceci, I learned that my axis need to be pointing in the direction of my stock so that the machine will go in the correct direction.

In my second go, I made sure that axis are set properly.

However, the program popped a question that if I'm using tool spindle 2. Something felt wrong, but I couldn't distinguish between upcut or downcut endmills. I referenced the manual to find that the person before me used

I noticed that the endmill is downcut whereas I wanted to use upcut. I referenced the manual to replace the downcut endmill with an upcut endmill. I used two different cut settings to cut, so it would take the machine two pass to complete the cutting. Here's the setting I used for my first pass:

Here's the setting I used for my second contour pass:

The cut finally works!

Assembly

Now it's time for assembly. I first removed all the tabs and smoothened the edges of each piece.

Then, I started putting all of the pieces together based on my design.

Here is the complete look of my chair!

I was a little worried about trying my chair because I didn't know whether the structural integrity can support my weight. Fortunately, it passed the human test.

Next step is to add the special paint to protect myself from the wood splinters. I also plan to add some paddings and some leather surface to turn the chair into a sofa that I can place in my dorm room.

Resources and Acknowledgements

Tools used:

Thanks to Dan and Ceci for helping me immensely on this week's work.

Design Files

You can download the Fusion 360 files here