[Mon Mar 26] Box one more try

Today we continued to work on our boxes. I started with cutting my revised design made during the break. I first realized that it was 1*1 inch instead of 2*2 inches and tried to make everything to scale, but Oscar said I will run into trouble doing 1*1 inch, and doing 2*2 inches at this point is just going to bring in more troubles. Therefore, I cut one of the three pieces of my design:

It turned out that the middle part was melted before the other parts were even cut through. I asked Oscar for a better design. Although later I realized that an important reason of why that had happened was because the middle hinges consisted of three layers of short lines on top of each other (that also explained why they look darker than the other parts...)

Anyways, Oscar showed us his samples of different patterns of the middle hinges. The materials he used were all thinner than mine (he used 1/8'' while I used 3/16 ''), so I wondered whether it would work on my materials. Here is his calculation/design:

However, Oscar recommended me to do mine on 1*1 inch first. Therefore, I recalculated and here is my result on paper:

It looks like this in Inkscape:

I cut it and it can bend 90 degrees if I try hard enough, and it looks very fragile...

But that should work. I went ahead to cut one more. Then I realized that I really need a model to see how they were put together, so I ran back to my room and brought back the model from last class. As I was trying to screw the two pieces together, one of the pieces snapped...

I think I was using too much force that it went over 90 degrees. But either way, it could not have worked because each piece was clearly too long that it wouldn't close up...

Therefore, I had to shorten the pieces- exactly the thickness of the material shorter, so that the pieces could close up. I drew it on Inkscape:

I cut it and tried to put these two pieces together first, but one of them snapped again... I went to see Kelsey's box, which had a similar design and could bend very easily. I asked Oscar for help. He said once I make the hinges on 2*2 inches, it should get better. But for now, just cut all three pieces so he could help me figure it out. I did that.

It wouldn't match...

I realized that I need to adjust the position of the holes on the short end - specifically, I should move it to the longer side by the thickness of the Delrin. Except for that mistake, Oscar said this design would work and encouraged me to try it on 2*2 inches next time. I drew the design for next class:

I will get rid of the colored lines later. Hopefully this will work!

[Mar 15] Joints Again

From last class' design, I noticed that the side could move towards the inside of the box. I can solve that by doing the same design on the other side. I went to the class an hour early so I can use the caliper in the lab. This is what it looks like:

My decision matrix for this design is:

Performance: ++

Manufacture: +

Aesthetic: ++

I ran my design by Oscar and cut it. Here is how it turned out:

The third piece could not go in because the edges wouldn't fit, although the size of the hole and the split were perfect. It was pretty durable in one direction, but if I exert enough force, it could be bent towards the inside because there is no third side in a different direction. I thought that it was reasonably prettier than last designs, so the actual decision matrix is:

Performance: -

Manufacturing: ++

Aesthetic: ++

Then I asked Oscar for help and we started from taping previous models together. We realized that three adjoined sides have to overlap each other in order to match up all the holes and splits. We also found out that the six sides are identical. I can construct the box by having two three-adjoined-sides together. Oscar recommended me to start from 1-inch sides. Therefore I drew another design as following:

The purple lines and black lines were for measuring purposes and were gotten rid of before printing because the first time when I had them, the laser cutter just moved rapidly without cutting anything...

Then Oscar trained me to use the electric screw driver:

It's very useful and you can use it to unscrew too.

But anyways, I eventually put together all the pieces:

Obviously, it's just two separate pieces. Although I think performance definitely improved in this design. The decision matrix for this one turns out to be:
Performance ++
Manufacture ++
Aesthetic + (because there is a big space left at the end of the split)

Then Oscar and I discovered that we can actually make three rectangular pieces with Kelsey's design:

That way two adjoined sides can bend in the middle so makes it a movable "spring" joint. My design for next class:

The middle part looks funky but I checked color and width of the strokes and they were all good... I guess I will have to figure it out when I go to class.

My expectation for the decision matrix of this design is:
Performance +++
Manufacture ++
Aesthetic +++

Hope that I will have time to figure something out when we come back from break.

[Mar 12] Laser Cutter Training, Joints Second Try

Today we started class by a training of using the laser cutter, so that we don't have to wait for Oscar every time we want to cut something. It was a good half-an hour lecture, but the process can be summarized as followed:

1. Make sure all the drawings are in 255 red and 0.003in. Save as eps. Although do save one as svg. for our own record.
2. Transfer the eps. to the "mac-pc combo computers" that is connected to the laser cutter, then open the eps. and print.
3. Click print preview in the print window. Then click "properties" to adjust the size of the "page."
4. Click print and it will open a new software (I forgot the name).
5. Select your document from the right side. It will show up on the screen (although it's only in shades). Go to view and check the "you get what you see" option, so you can see the drawing. Then put the material in the laser cutter, find the red spot, adjust the height of the laser cutter from the material with a given red piece of plastic.
6. Click on "plug" button on the right bottom corner of the software. It will detect the position of the point of the laser cutter on to the screen. Move the picture to its relative position to the point of the laser cutter.
7. Adjust the speed and the power of the laser cutter on top. The thicker the material is, the slower the laser cutter should go.
8. Check everything and click the green go button.

We all went on and practiced. I started to try do my (2) design from last class. However, the laser cutter definitely cannot cut rounded corners, and it would also be hard to drill holes in materials, so (2) will be hard to build with the materials we have. I asked Oscar how I could make it happen. He wanted to see my product from last class, but I left it on my desk, so that was a lesson learned. Oscar wanted me to quickly redo my design, which turned out to take rest of the class time.

The problem with last class' design was that the screw was too big and I didn't use the appropriate tools. Today, I started to design with "0" screws and with the caliper. I measured the diameter of the screw to be 0.0540in and the sickness of the material is 0.1250in.

I set the diameter of the hole to be 0.054 as measured and got rid of the nut because we don't have any nuts for #0 screws and they weren't very functional anyway. Oscar showed me a way to draw things accurately with inkscape: draw rectangles and set its position and size on the tool bar.

I thought I did everything else as I did last time, but turned out I made a big mistake. Here is how it turned out to be:

The opening were not matched and I forgot to draw the hole. But this attempt was valuable because I found that the cutting was too big. I measured the opening to be 0.0630in, almost 0.010in more than what I wanted. Therefore I set the spot for the screw to be 0.0400in instead and fixed the openings so that the match. Then I realized that the height of the opening was not accurate - it should be same as the thickness of the material. It came across before but I never thought harder because last class I didn't worry about this and my opening was by luck a good match. Anyways, I set the height of the opening to be 0.125in.

Here was what I got:

A couple problems after it's assembled [I lost the picture :(  ]

1. The opening didn't match very well, so the two sides were very loose.

2. The hole was too small.

3. #0 screws don't have phillips screw head, so the screw driver couldn't stay on the screw all the time and made assembling very difficult.

4. The spot for the screw was too short.

Conclusion: switch back to #4 screws. I thought that it was really sad because that was what I had last class, but Oscar said that it was worth trying. At that point, it was 5pm so I decided to come back to it later.

[Mar 8] Designing the Box

Today we started our own design process! It sounded challenging but exciting.

Since no one e-mailed any ideas to Oscar, he decided to assign us a project - making a box. There are, of course, some requirements. The box needs to be 2 * 2 inches for each side. It could have any number of sides, although for simplicity reasons, many of us chose cubes. It needs to have 2 fixed sides, 2 movable joints that are either free or friction or one for each category for a bonus (although no one knew what that meant...) Oscar wanted us to give him a materials list. It should be aesthetic, easy to manufacture, and have high performance.


I started my design process. And here is my overall design at this point:



(1) is fixed joint, (2) is movable joint (could be free or friction, depending on how I make it), (3) is a fixed point but not as strong as (1).


I searched for laser cutting boxes, and found this wonderful design:
http://www.redtorope.com/2010/08/beer-mat-boxes/

It is a great design for fixed joints, and this is where I got my (1) joint.

(All from "RedToRope")

I loved this design because then it wouldn't require drilling a hole across the material like (2) does. It would also be very stable and somewhat aesthetic (at least it looks pretty in the picture...) I showed Oscar and he thought it was a brilliant design too so I shared with everyone else.

This is my design matrix for (1) before I tested it out:
Performance ++
Manufacture +
Aesthetic +

Then I started drawing it with Inkscape.

I measured the length of the screw with a ruler, which turned out to be a bad idea because it was not accurate enough for this kind of work. I should have used the electronic ruler. But anyway, the screw was a little more than 2.5 cm, so I made the spot for the nut 2 cm from the top of opening. Then I measured the width of the screw to be 3mm, so I made the opening 3mm wide. Then I measured the width of the nut and made the space for the nut to be that measure. I made the diameter of the little hole 3mm.

Then I set everything to the correct format, and used the laser machine to cut the design. Here is what it looks like when it's assembled:

I was in luck that the screw could just go in and made the joint very stable. Because of the measuring issues, the width of the space for the nut is too big while the length of the space for the screw is too long, so that the nut is movable and not really functional. In fact, I think I might have lost the screw that I was measuring and used the other screw when I assembled it... The hole and the space for the screw were also too small. The crew could be pushed in with a screw driver, but it was really hard and could not be put in back and forth because otherwise it would "eat up the materials" and become looser and looser.

Another problem is that a screw of this size is too big for a 2*2 inch box. It's also not very pretty. Oscar helped me find "0" screw, which should be better for this project.

The decision matrix after the experimentation turned out to be:
Performance + (Can be fixed by using caliper)
Manufacture +
Aesthetic - (Can be fixed by changing to smaller screws and nuts)

Lesson learned today:
1. Always record what materials I used
2. Always use accurate measuring tools, eg. caliper
3. Go step by step. Testing out partial designs before going on to the whole project.

That was all we had time for. I am excited to test out my (2) next class.

[March 5] Laser Cutting, Design Process

Today we started class by laser cutting our designs! I apparently didn't save my design at home to svg., so I had to redraw it, but that took shorter than I thought. I just traced the line on top of the image. After I made everything relatively smooth, I set the hairline to 0.003 inch and color red 255. Then I saved it as svg. and transported my file to the computer connected to the laser cutter.

Oscar changed the format and clicked print. I was surprised that it's just "print" instead of some fancier word. But anyway, the cutter didn't seem to like the left up corner of the "cutting board." Some part of my carabiner almost got melted but it turned out okay.

Some parts were a lot thinner than I thought it would be. Therefore, it was really bendable at the opening, which solved my previous concern, but it would not be able to take on lots of weight. It seems like a trade-off right now but I wonder whether there would be a way to get around it.

We waited until everyone had their carabiner. Then we moved on and started to talk about the design process. Simply speaking: do things scientifically step by step. Oscar introduced us three different processes (apparently there are thousands of ways to do it, depending on time, industries, locations, etc.)

The first process was presented as below (product):

This process was from the 50s. In some situations, engineers are given a problem and are told to solve it. Oscar noted that we would probably encounter problems in each stage and have to go back and refine before we can move on. This is part of engineering.

The second process was presented as below (iteration):

This process started with identifying a problem and incorporated the process of ideation (the process of expanding ideas) and selection (the process of narrowing down ideas). At the end of the process, we would probably find some new problem and we go back into the process and solve the new problem again.

The third process is presented as below (user):

This process is only the first step in the "product" process presented earlier. Not thinking about users makes engineering process fail, so having the user in mind is very important. This process incorporated codesign, in which engineers present their design to users and ask them whether it would be useful and what else it should do and then go back into an earlier stage in the process.

Oscar also mentioned several other points during the design process.

First, support, maintenance and upgrade. Engineers should make sure that users know how to use, maintain and have access to help after they are given the designs. Otherwise, the designs could break down easily, and users would never get it fixed.

Second, business venture. This is the question of how to actually sell the products and promote the designs.

Third, environmental impact such as life-cycle analysis, disposal. This also includes that engineers should find out what is the first thing that will fail and focus on fixing that because once the first thing fails, the whole design fails no matter how perfect it is otherwise.

Last, social impact. This is to realize that engineers are changing the world and they are responsible for the purpose of their design.

The engineering process can also be presented in a circular diagram:

Good engineers agree on process, not just blindly observe and find problems. They make sure their designs are usable.

At the end of the class, Oscar showed us the inside of hard drives. It had some very smart designs, such as a set of magnet design to keep the magnetic field between the two metals. One part of the hard drive looked like old CD player. It had a head and a circular disk. The disk can spin while the head can move farther or closer to the center of the disk; that's how hard drives find documents that we are searching for. Hard drives are very delicate designs: once we open them, they are not usable any more because they need to be very clean everywhere. We played with them and I left first, permanent, and dirty fingerprints on one of the disks.

Then Oscar showed us hard drive shredding machines, which are actually pretty powerful.

[Mar 2] SolidWorks, Inkscape, Laser Cutter

At the beginning of today's class, Oscar said that we were going to use laser cutter today. That was so exciting! I have heard about laser cutters many times but never knew how they work and why people love them.

Anyways, each one of us got our own computer. Essie and I couldn't use the computer on our desk because we accidentally killed windows last time... Then we downloaded a software called SolidWorks, which took a long time to open. We started with the first tutorial to make a cool shape that looked like a camera to me. The tutorial was very straightforward and helped us explore different features of the software. We started with the front face and eventually made a rectangular cuboid with certain dimensions. Then we added a cylinder on the front face that looked like the lens of a camera. Then we filleted the edges to make the shape look smoother (and more like a camera). After all, we had to make it void on the back. The tutorial was really helpful all along this process because I would otherwise have no idea where to start and how different features can be used.

At some point, I was really confused what this software was for. I asked Oscar and he explained that it was a software that enabled us to design a 3D model. That made a lot more sense and made me feel a lot more comfortable at what I was doing.

Towards the end of the tutorial, Oscar stopped us and asked us how to transfer this design to something that the laser cutter could recognize (since it only operates on two dimensions). We thought that it was too hard to do, especially since we just started mechanics. Therefore, Oscar introduced us to an easier software that does two dimensions - Inkscape.

Inkscape was free to download, which was nice because we could play with them when we went home. (I did end up spending some time fixing my design outside the class.) Inkscape looks like Paint, but it has lots of cool features such as drawing different kinds of curves. Our project was to design a carabiner - something that can hook to something else. Then we just started our own projects. I needed some help figuring out the size of my design, but all was well.

So my design at the end of the class was like this:

Later Oscar commented on my design and said that the opener was too big. I was worried that since the material the laser cutter used was thick and hard to bend, I would want to make the opener bigger so that things could get in from the opener. But Oscar said that if I made some part very thin, then it could bend. I never thought about that before.

Anyways, Cailey finished first so Oscar transferred her design to the laser cutter and set everything to its correct format. The inside of the laser cutter looked like a beehive. Oscar moved the "beehive" up and down to adjust its height from the cutter. Then it started cutting! There were sparkles and all that. It was really cool. It took about six tries to actually cut the design.

Then we tested the design, except for we couldn't because that would require a more complicated set-up. But Cailey was very happy with her design :)

Next class we will finish up our designs and cut them!

After hearing Oscar's comments, I revised my design and here is what it looks like now:

It should be able to bend near the opener. Oscar said I always want to know what will happen before I do them, which I think it very true. But engineering is a process of doing things not knowing whether it will work or not and keep revising it after failures. I will try to develop that mentality. Can't wait to test it!