Chair CIM 24 IP

First Thoughts:

Going into this project I want to do something that will stand out and be unique, I want to focus on making a really cool stool that can also serve as a piece of art. Functional art is a big interest of mine and I feel like the Willow School philosophy is extremely art-centric, so it should work out for the best.

Problem:

Efficient and orderly seating is a must in heavy traffic zones such as the 1st floor hallway. Challenges such as cluttered hallways lacking seating negatively impact lunch because designated seating spaces promote clear pathways. This is especially important because the lunch line lingers well into the 1st floor hallway that many students use to eat, and kids will sit in the worst and most problematic ways possible. There are additional hazards surrounding blocking heavy traffic zones such as: impeding exits, adding extra difficulties to people with movement issues (wheel chairs), it is inefficient, and can be unappealing to visitors or potential students (messiness).

• Wood - 405mm by 405mm plywood sheet
• CAD Software - Fusion 360, used to sketch and model designs
• CNC - used to cut out the exported DXF files, uses a drill bit with instructions in the form of g-code
• CNC Software - Carbide Create, used to put specific cutting instructions in for the CNC to operate in the form of g-code
• Cutting Tools - chisel needed to cut through the tabs, drill bit used on the CNC (specialized for wood cutting), and sand paper to get rid of rough edges

Initial Steps:

These are some of the stools I saw from a brief search, they're all very unique and have very cool features. When looking for prior solutions I looked up chairs and searched for the most compact and eye catching ones. Once I gathered my images I examined the strengths and weaknesses of a few to determine what qualities I should focus on when designing a chair.

Strengths and Weaknesses:

(chair composed of vertical pieces)

Strengths: Extremely aesthetic design, very stable since it has a lot of contact with the ground. Would work very well on many different surfaces, and mobile since it is so small.

Weaknesses: It is not material efficient in the slightest, I tried designing one of these chairs and it required an immense amount of wood. Not very easy to assemble since there are no notches or joints that are visible. 

(gear shaped stool)

Strengths: Extremely sturdy and durable, it uses very thick wood which means it will be around for a long time and will last through wear and tear. Space efficient, very small footprint since it is a stool.

Weaknesses: Does not look lightweight despite its small size. Uses extremely thick wood which will not be an option for the project. Lacks back support for the user. Not easy to put together, it is a piece of art with all of its screws hidden away in pockets.

The objective is to solve the problem by designing a chair that will blend in with the rest of the hallway, optimize efficiency, and mitigate hazards. It will tackle the need for extra seating in the hallway, and help to cluster students  together in certain locations. It will focus on space efficiency, aesthetic, and functionality while also being comfortable. 

Criteria

Space efficiency - must have a small footprint to fit in the narrow hallway

Stability - should easily support any student who uses it, shouldn’t creek or bend

Durability - must be able to withstand frequent use in a popular space

Easy to put together - if more are made, they should be straightforward for anybody to assemble, preferably without any hardware or tools

Mobility - must be lightweight and easy to move in case the hall space is required for another activity (PE)

Aesthetic - must fit in with the Willow aesthetic (basically anything) and be very creative and visually appealing

Constraints:

Space limitations - the chair must be compact enough to ensure that traffic flow is not hindered

Ease of assembly - should not use fasteners like screws or any other hardware to keep the assembly time low

Weight limitations - the chair must be lightweight while still being stable and usable

Material limitations - must be cut from a 4’ by 4’ by ¾” piece of plywood, using the CNC

Stability - should not deflect or make any sort of noise/movement when a student uses it

Manufacturability - must be made in the Maker Space (CNC)

Design 1: (left)

I started designing the chair that is only composed of vertical pieces, but I'm going to put a spin on it. Instead the seat being a square/rectangle shape I will make it circular. The chair will also be convex instead of concave, I would also like to add holes in the legs so I can insert tabs to increase stability. My only concerns with it so far is the amount of material I will use, I don't think it's too much so I'm just going to pray. The blue arrow is pointing at the top view of the chair, and the red arrow is pointing to an extruded section of the chair. There are 15 individual pieces and there will be two of each except for one. This design never got past this stage because I found out that it would require too much wood and would not be material efficient.

Design 2: (right)

I started this design my using a tape measure and the normal, blue school chair I was sitting in as a reference. I started measuring and making various rectangles and dividing them up in to parts: legs, arms, and back. This gave me an idea of how long and wide each piece needed to be. I essentially made myself a large ice block and sectioned it off into three different parts, then I started to chisel at it and slowly find a design that was appealing. If I though the sketch was too flimsy I added more cross-members, and finally, I used the fillet tool to make every single part of my sketch nice and round. I then added joints and slots so the design could be assembled without any kind of hardware.

All chair pieces arranged in the most compact and space-efficient manner, then converted to a DXF file to be imported to carbide create. Then once imported into Carbide Create the stock size, thickness, and retract heights had to all be set to insure a proper cutting procedure. Next, the scale tool was used since the imported drawing was the full scale chair. A scale factor of 0.2624 was used, this number can be achieved from converting the full-scale wood thickness of 0.75 inches to mm ➡ 19.05mm, then dividing the model woods thickness of 5mm by 19.05mm ➡ 0.2624 rounded to the nearest ten thousandth. The feed rate had to be increased along with decreasing the amount of passes it takes to go through the wood.

Cutting Procedure:

Once the cutting surface was set correctly, the toolpaths had to be set up. These toolpaths included an inside path and an outside path. Each max depth should have been set to 5mm, but a user error occurred and the outside depth was set to 2.54mm. Next, tabs were added so the cut pieces did not fall through after cutting. Four tabs were added per piece. The g-code was uploaded to a flash drive, then inserted into the laptop where it was then cut.

There was an error somewhere in the g-code where the piece of plywood was not milled all the way through. I am currently waiting to mill another piece, but I am last in a queue of people who have not cut a project yet. Once it is properly cut, I will be able to quickly assemble it because of it's ease of assembly component and will get right to testing.

Testing:

I will test the chair by pushing down on it with my bodyweight and moving from side-to-side to see if the chair deflects in any manner. If the chair is structurally sound I will then commence on making the full scale final product to be implemented in the 1st floor hallway.