HS-Dt-S1-Ivan

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Design Folder - Ivan

Unit Question (UQ)
The DT lab is overflowing with cardboard. How can cardboard be used to make a stable chair with back support capable of holding a 150 lbs person without using any fasteners, glue or tape?

Unit Question Interpreted
Cardboard is used often but also wasted very easily; people usually consider cardboard to be used once and throw it away. However, these cardboard can be used to create useful objects in our life, such as a chair. A chair is an essential object to many people, and it is definitely one of the most common and useful tool. In out DT lab, we also have a lot of cardboard kept and not used. Therefore, why don't we use those cardboard to create a stable chair that can actually hold a person?

Design Brief
A chair is part of our life, especially to students like me, and it can be made out of cardboard, which is a good material that is overflowing in our DT lab. I am making this chair for anyone who needs a place to sit, only if he or she is not too heavy, and to demonstrate that we can view materials in different ways and reuse them. The main problem of this unit is to not use ant fasteners, glue or tape while creating a chair; to do is I will use different kinds of joints that will attach pieces of cardboard together and hold is strongly.

Design Specification

 * 1) It must be in a form of a chair
 * 2) It must hold a 150 Ibs person
 * 3) It must have a back support
 * 4) No fasteners, glue or tape should be used
 * 5) It should be in the appropriate size
 * 6) It should be comfortable and ergonomic
 * 7) It should be attractive
 * 8) It must be simple to not use too much time

Investigation with Notecards
The first thing I had to think about was what can I do to make this paper to hold a lot of wieght? The first idea was a cylinder as shown on the left image; the cylinder was able to hold a lot more weight then I expected, but there were points of failures observed as we experimented. However, if I make the cylinder more strong and durable, I believe I can use this as part of my design. The second idea, which came from Mr. Muller, is using slits, as shown on the right image. Cutting each pieces halfway through and attatching them together created a strong connection, especially in the center where they meet. This joint is pretty durable and depending on how you use these slits, I think you can also come up with various designs. These are the first two methods that can be part of our chair designs.

. In class, Mr. Muller told us about using 'foldings' in various ways and also told us that a triangle is the most stable geometric shape. After listeneing to this, I tried folding a square notecard in different ways and made a form that looks like a pyramid but with no sides. However, since it was not able to have an object on top of it, I cut the top flat and that is what the image above shows. There was still one more problem with this and that was the bottom part of it which will keep open up since it is folded. First, I didn't know how to solve this but to test the durability of the design, I taped the bottom part and put some objects on top of it. Surprisingly, it held a lot of heavy objects, a lot more than the cylinder and the slits did. After finding out the durability of it, I had to come back to fixing it's main problem with using no fasteners, glue or tape. I just didn't want to fix the problem but also make the structure even more stable, and Mr. Hassan gave me a hand for this. I used the slits to connect each edge to the side next to it; it is hard to explain it in words, but the images below shows how it looks like.

The left image is a picture from the side and the right image is how it looks from the top. It is a small structure but it does hold a lot of weight as it shows in the image below.

1) First Chair
To create the first prototype, I used the method of cutting slits (also inspired by a video on YouTube). The structure of this chair basically consists of two pieces, which are the side of the chair, on each side that has slots, and I have several slots connecting these two pieces. The slots will be the seat and the backrest where the weight will be added to. The prototype was a failure to me because it was not really stable and the slots were not straight, even though I measured and cut it correctly. Additionally, the back rest was weak because it did not have a strong connection with the seat, so it seemed like it will easily tear off. I failed to turn the two dimensional image into a three dimensional object; the problem was that I did not precisely measure the width of the part that I cut, and for the backrest, it was not strong or sustainable at all; I had to come up with a new idea for the backrest.

2) Second Chair
My second prototype is a lot more simpler and there are basically two pieces that makes up this chair, the base and the covering, which is also a backrest. The base is the structure I created during my investigation with note cards that is shown above. The covering, which is also a backrest, basically covers the base, so that it looks like a cube, and additionally creates a backseat by folding. I expected the back rest to be weak at the first place, but the main purpose of this prototype was to create a chair using the structure I made, trying to test its strength and stability. The base was pretty successful, but the problem of this chair, as I expected, was the backrest. I was not able to come up with a supportive and sustainable backrest yet, and that is what I am going to work on.

[[image:aisd-dt/Paper_Chair_3-1.JPG width="312" height="237"]] [[image:Paper_Chair_3-2.JPG width="333" height="266"]][[image:Paper_Chair_3-3.JPG width="318" height="244"]]
For my final prototype, I blended the structures of the two previous prototypes. The base is the structure I used as the base for my second prototype; I covered it so that it will look like a cube, which will have a flat surface that is easier to sit on. Then I built two same pieces for the side of the chair just like the first prototype. I made them to fit into the gap that the base had at the side, and then connected the two with slots. Additionally, I added two more vertical piece at the backrest to provide more strength, hoping that it will be supportive enough. Basically, the chair is divided into two major sections, the seat and the backrest, as shown in the second image above. The chair was not a success though. The problem I had was the connection between the backrest and the base; the bottom part of the backrest was too weak that it seemed like it will tear off if someone actually sat on the real chair of this prototype. Still, the strength of the backrest was fine and I could even strengthen it more by adding more vertical pieces too it. Now, the only thing I should do is to strengthen the connection of the backrest and the seat.

Guiding Questions

 * 1) What size should my chair be?
 * 2) What is the average height of a chair?
 * 3) What is the height of the seat and the backrest of a chair that people find comfortable?
 * 4) What is the ratio of the length of the seat to the backrest of a comfortable chair?
 * 5) How do people prefer to sit on a chair?
 * 6) How long will it take to create with cardboard?
 * 7) What should I be careful of when I use a cardboard?
 * 8) What is the difference in properties between paper and cardboard?
 * 9) What is the best way to fold or cut a cardboard?

Quarter Scale Model
I had several issues that I faced while I started to use cardboard to create my quarter scale model. One of the main problems is that folding a cardboard is not as easy as folding a paper. This was critical to me since the structure I planned to use for my final chair needs a lot of folding and precision. I learned how to "score" a cardboard, which helped me to fold the cardboard in straight lines, but the problem was that it was still less precise than the note cards because the cardboard is much thicker than the note cards. I tried several times, but I failed to build the structure I wanted to. In other words, I had to abandon my design and come up with a new one.

Final Design/Plan
To come up with a new design I used SketchUp to see how my design looks like and the images below shows my final design and plan. The dimensions are written for the quarter scale model, not the dinal model, so to find out the dimension of my final model, you should quadruple the dimension shown in the images. It was hard to show all the details in SketchUp, but the design is showing four rectangular prisms, at a height of 10cm, with a slot in each of it for the base. There are two more rectangular prisms, but two times longer than the ones used for the base, and these also have a slot inside but it is facing a different direction. As a result, there are six rectangular prisms that forms the shape of a chair, and I was thinking of putting them together with one large piece that will cover around all the prisms. The dimension is from the chairs in the DT class, which I found pretty comfortable, and I think the proportion is fine. One of things I am concerned is that it might not be ergonomic because the backrest is perfectly perpendicular to the seat, and there is no one I know who sits on a chair perfectly straight in 90 degrees. Also, I was thinking of not covering the seat because I thought it was unecessary, but maybe it might be a bit uncomfortable when it is made in the actual size.

[[image:Quarter_Scale_Model_-_1.JPG width="451" height="342"]] [[image:Quarter_Scale_Model_-_2.JPG width="464" height="351"]]
This is the final design and my quarter scale model, and I'm pretty sure these images will provide a better understanding to my design. As explained above, there are four rectangular prisms for the seat, two longer prisms for the backrest, and a covering that keeps everything together. The difference you will see from the SketchUp design is that there is a small triangular shape at each side on the covering. I added this to provide more support to hold the pieces together and that it will be stronger when you lie back.

To create a rectangular prism without using any fasteners, I created locks to connect the end of two sides. Then, for the seat, I cut out two pieces that will each fit into the prism diagonally, like in the left image, and cut a slit on each of the piece to connect them, which will make the entire thing fit into the prism. For the backrest, I also cut out two pieces but in a way that will fit differently. I had to make the "X" facing where the weight is added to the chair. The covering is just one large piece that surrounds all the other pieces and keep them together as I explained for the design.

The chair turned out to be pretty strong, more than it needs to. To experiment the strength of the chair I tried standing on the chair, and surprisingly it was able to hold my whole weight. Also, I asked all the other people in the class to try it, and the chair was capable of holding every one of them. Clement and Cherub obviously weigh more than 150 pounds, which means my quarter scale has already achieved the goal of "holding a 150 lbs person without using any fasteners, glue or tape."

Final Chair Creation
I started on creating the columns for the seat, which is shown above, and I had to face some problems while creating this. First, I wasn't able to fold the cardboard as I wanted to; because cardboard has grids on it and some already are folded, it didn't fold perfectly and didn't maintain the shape. Also, it was a lot harder to lock the cardboard. For the quarter scale, I just had to cut a line and put the lock into it, but since the cardboard is a lot thicker, I had to create a bigger hole and struggled on putting the lock into it.

After I created four of the columns for the seat, I realized that they didn't maintain the shape at all. Each of them had a side that sticks out due to the scoring for the lock, and since they are all slightly different in dimension, the columns didn't maintain the shape at all when they were all put together. Additionally, I faced another problem during the creation. In order to complete the chair and put all the pieces together, I needed a piece that covers all the pieces and keeps them togeter, but I was not able to find a cardboard that was big enough for it. Now I have two more guiding quiestions which are:
 * How do I maintain the shape?
 * How should I keep all the pieces together?

After