Blog Entry 4 (Covers Practical 5)

In this post, I am going to be talking about Practical 5. In practical 5, we form pairs and were tasked to do the egg drop challenge. We were asked to design and make a device that a raw quail egg to survive a drop of 2 meters.

There were a few requirement that we had to follow: 

1. The device must be entirely 3D printed and does not require any non-3D printable parts.
2. Requires minimal post-processing & make efficient use of material

My first thought after looking through this was that it was going to be difficult and I was right but at the same time this entire journey has been quite fulfilling as well. After some discussion of how to start about designing it in fusion 360, we decided to go in this order. Where we will first make an egg then create a mold (box) to hold the eggs in. After that start creating the arch and then the latch for the box.  

Here is the sketch of our design:

Reason why we design it like that

The outside of the design covers the box, something like an arch. The extra surface area will reduce the force of impact to the egg acting like a dampener. 

Therefore, when it hits the ground, it will bounce slightly and reduce the speed of dropping on the ground. It will increase the air resistance which will reduce the stress level. This will protect the egg from cracking. 

Moreover, there is also a box to hold the egg. 

The box is something of a second layer of protection for the quail egg. This helps to absorb the impact to ensure the stress level to the egg is at the lowest level. 

For the overall shape of the design, for the arch we are actually trying to mimic the shape of a sphere. Not a very perfect sphere, but close to its circle-like shape. This is because the circle is the strongest structural shape and corresponding to that the sphere will be the strongest 3d shape. Reason being that stress is distributed equally along the arc of the circle instead of concentrating at one point. 

After doing up the box, we realized that there wasn't any way for the box to remain closed during the fall yet. After some research, we decided to include a latch on both bottom and top of the box. This will help the egg to stay inside the box during the drop and not fly out.

Designing the device in Fusion 360

 

Making the egg

1. In order to make the egg, we had to first find out the dimension of the quail egg. Based on some research off the internet, it was said that a quail egg dimension is 35mm in length and 27 mm in diameter.
2. In Fusion 360, Click create sketch and choose the front plane.
   

   
3. Select the line function and select construction line and create 1 vertical line that is 35 mm in length and 1 horizontal line that is 27 mm. 

   

   

   
   

   
   
4. Then Drag the horizontal 27 mm line so that its midpoint is resting on the vertical line. To do that press constraints at the top and select midpoint. Select the horizontal line then click on the vertical line. This will shift the 2 lines.

   

   

   
   

   
   
5. Then click on the horizontal line, right click and select move/copy. Move the horizontal line slightly to the bottom. I move it down by 5 mm. This is because the 27 mm line is going to be our widest part in the egg and the egg widest part is not at the middle but closer to the bottom. 

   

   
6. Then at the top click fit point spline, and select the 3 points that the spline is going to be locked at to create the shape of the egg. 

   

   

   

   
7. Then slightly adjust the spline so that it is at a angle that you want. 

   

   
8. Since the vertical line is still a construction line, click on that line and click construction line to make it solid. 

   

   
9.  Then click finish sketch. From the top click create, select revolve. Select the egg sketch profile and for the axis to revolve on select the solid vertical line from step 9. 

   

   

   
10. For the angle select 360 degree, and you will get an egg! 

    

Making the mold (box)

1. Select create sketch then select the left plane. 
   
   
   
2. Select rectangle function from the top, then select the center rectangle. 

   

   
   
3. From the middle of the egg, click and drag to form a rectangle with a dimension of 55mm by 47 mm. 

   
4. At the top right hand corner, click and shift the design to the back plane. 

   

   
   
5. On the keyboard, press the letter "e". That is the keyboard shortcut for the function extrude in Fusion 360. Select the middle line on the egg as the profile to extrude. That is the side of the rectangle that we did on the left plant in step 3. 

   

   
   
6. Ensure that the direction is set to " Two Sides". You Should see two arrows pointing at the opposite direction. You can either drag the two arrows to extrude or key in the length you want to extrude in the bar. I extruded both side to 22mm. Also Change the operation from "cut" to "New Body".

   

   
   
7. Go to the top, Click Modify and select Combine. 

   

   
   
8. For the target body select the box, for the tool body select the egg. Select "cut" for the operation. This will help to cut the egg away and make is so that there will be a egg sized hole we can place the egg in the box. 

   

   

   

   

   

   
   
9. At the top select construct then midplane. Select the plane at the left and right and click ok. 

   

   
   

   

   
   
10. From the top select modify, then split body. Select the box as the body to split and the midplane that we just created as the splitting tool. This will split the box into two so that we can put the egg in.

    

    

    

Creating the arch 

1. Go back the front plane. At the browser, click on the eye icon for the bodies and components to make them disappear. Then click on the eye icon at the sketch to make the sketches visible, select the egg sketch and the center rectangle box sketch and make them visible. 
   
2. Select create sketch and select the egg sketch profile. Then select the control point spline. 

   
3. Then click on the points that you want the spline to lock into and create an arch shape. Click on the tick once you want to end the arch. The tick should turn green. Finally, click finish sketch. 

   
4. Then switch to the top plane. Select create sketch, choose the center diameter circle. Create a circle and key in the diameter as 5mm. then click finish sketch.

   

   
5. Go back to the front plane. Select the circle, right click and select move/copy. Move the circle to an end of the arch created by clicking on the arrows or square and dragging it.

   

   
   

   
6. Press keyboard shortcut "S" for search. Search for 'sweep' function. Select the circle as the profile and the spline as the path, click ok. 

   

   

   

   

   
   
7. Make the bodies visible again. Press "S" for search then search for rectangular pattern. Change type to body. Select the arch as the object and select the lines of the box as the direction to drag.

   

   

   
8. Do as many arch as you like for one side. I did mine like this. 

   
9. Then press "s" on the keyboard and search for mirror. Change the type to body. Select the 5 arches as the body and select the left side of the box as the mirror plane.

   

   

   
10. Left click, select move/copy. Select the 5 arches created and drag it so that it align to the other side. 

    

    

    
    

Creating the latch

1. Go to the bottom plane. Create sketch. Select Center point rectangle and create a rectangle. 
   
2. Hide 1 side of the box. Hit "e" for extrude then extrude out the rectangle by 1.5mm and click ok. 

   
3. Go to the other side of the latch and create the protruding part by choosing two point rectangle drag it until it hit the middle of the latch rectangle. Then hit finish sketch and extrude it by 2mm. Go to modify at the top, select chamfer, click on the 2 top and bottom lines of the extruded piece and chamfer it by 1mm. 

   
4. Repeat this on the top plane.
5. Make the box that you hide visible again. Select combine, target body will be the side just made visible while tool body will be the side with the latch. Change operation to cut and click ok. You should see a hole for the latch to latch onto.

   

   
6. Do this for both top and bottom. 

Final Device 

I have embed the final device here. 

 

 Here are some screenshot of it at different angle also.

CURA Slicer Software

1. Launch cura, select the 3D printer that is going to be used. 
2. At fusion 360, Go to file at the top. Select export and change the file type to stl. Then click export. 
   

   
   
3. Drag the stl file to the cura software. Change the profile to fast 0.2mm and the layer height to 0.28mm. 

   

   

4. Since, we printed the arch and the box separately, you can adjust their orientation respectively so that it will not need as much support.  For the arch, you can orientate it like that. I also added a brim for the arch. 

   

5. For the box though, the orientation is still upright with supports. Since the 3d printer works by printing layer by layer. We took the orientation of the layers into account when deciding on our design. When printing out, we specifically printed out in this orientation. The upright position. Instead of it lying flat even though it will be faster.

   This is because by printing it like that the force of the device dropping will be perpendicular to the layer lines or grain lines that is 3d printed.

   Instead of the force being parallel on the grain line which will make the device weaker. It will be easier for the device to break along the grain lines if the force is parallel then if the force is hitting the surface perpendicularly.

   
6. Then click on the slice button. It will then show you how long it would take to print it. The longest time that one of our parts took to to print was around 4 hours. What we did was to print them concurrently using different 3D printer to save time. 

   

   
   
7. Then after slicing click on save to disk, select gcode as the the file format and save. 

   

   

   
   

   
   

   
   

Operating the 3D printer 

1. Switch on the electricity for the printer.
   
   
   
2. Grab the filament from the dry box.
   
3. Place the filament into the preheater below the printer.

   

   

   
   

   
4. Push 1 end of the filament into the bottom hole.

   
5. On the control screen press load, and wait for it to load the filament into the printer. Some plastic might come out of the nozzle, just scrap it off with a tool.
6. Since, I am using Ultimaker S3 I do not need a SD card or adapter as it works by the thumb drive that comes along with it. Insert the thumb drive into the laptop and drag the gcode file in to the thumb drive.
7. Plug the thumb drive into the printer, select "start to print" and select your file on the control screen to print. You might have to wait a while for the printer to load.

   

   
   
8. Afterwards you should see it start printing, like this:

   
9. Once the printer stop printing, wait around 5 minutes for it to cool down. Then if it is still hard to take the object out, use a scraper and gently scrap the bottom to introduce air to the bottom. This should help get the object to unstick from the plate and get it out.
10. Grab a tool like a sharp plier and remove the supports and adhesion from the object.
11. After printing everything wait a while for the nozzle to cool down then switch off the printer and turn off the electricity.
12. After that we just use super glue to glue the arch and the box together like the way shown in fusion 360.

Some pictures of our device

One side of our box with the support still in

Some of the arch that was printed.

How the arch look like outside the box

Inside view of the device where we are going to place the egg

Hole that the latch is going to latch onto

The protruding bits at the top and bottom of the box are the latch (Not the arch)

View of the device fully close

Video of the egg drop device in action 😝

Our egg drop device work!!!🥳🥳🥳

We have also cracked the egg in the end to prove that the egg was indeed raw.🥚

Reflection 

When we first learned that we had to design a 3D object for the egg drop challenge. We were worried and tentative as this is our first time that we are going to have to design and make our own 3D object. We had used fusion 360 before to design other things but that was with instructions while for this egg drop challenge we were given free reign to design it however we liked with no instructions only that it was for a quail egg.

We ended up deciding to make the egg first in fusion 360 and use it to create some sort of mold box so that there will be an egg shape for the egg to lie in. We then added the latches for the box to close. We also decided to add the arches in as we were uncertain if just the box was enough to protect the egg. The entire design of the device took around a week as we didn't have instructions on what commands and functions in fusion 360 to use hence we had to do some research and watch some videos on how to go about using those functions. We especially liked the function "mirror" as this helps us to mirror bodies into the other side which saves us a lot of time as we do not have to redo the bodies again just for the other side.

It was also the first time that we actually had to use the 3D printer to print out the object we designed. This was where we learned that designing it is one thing but to actually 3D print it is another. As when we actually have to print it we learned the hard way that when designing we have to take into account many things beside the actual design itself. For example, the size of the 3D printer. We originally designed the device with a bigger scale compared to what we have now, but after placing it in the cura slicer software, it showed us that the dimension of the device was too big for the 3D printer that we can use in the workshop. This means that there is no way that the 3D printer can print our first design. It was quite frustrating as it means that we had to redesign it in fusion 360 again making it smaller in size.

On the day of the actual 3D printing, since we were one of the groups to first use the 3D printer during that day. We actually ran into some problems. Such as the PLA material was unable to be loaded into the printer. We had to try multiple times and even had to give the PLA a push at the back in order to aid it to travel upwards towards the printer nozzle. Afterwards when we started printing, the printer suddenly stopped 30 minutes in and said that it couldn't detect any feed material even though we could see the PLA in the feed tube. We had to stop the printing and scrap off what was already printed and try again. We ended up having to use alcohol wipes to wipe the nozzle before it could work. From this we guessed that the nozzle was dirty and hence wasn't letting any of the PLA out. This took us about 1 hour. Afterwards our design for the left part failed in printing where it wasn't making the shape we wanted. We ended up having to redesign it slightly and decided to print out the parts separately for the printer to work. Another problem we ran into was that, while printing out the parts the nozzle kept pushing the PLA off the plate, at first we guessed that it was because there wasn't enough bed adhesion but after adjusting that, it was still doing the same thing. Luckily, we encountered seniors and teachers there that suggested we change the "Z" orientation to a negative number for example -0.4. They told us that after some time, some printer beds might slightly shift out of alignment. So in order to make up for that we will have to change our "Z" number in cura. The numbers for "Z" will also vary printer to printer as different printer beds might shift differently. We never know. In fact the negative numbers that our senior told us to use, they only got it after some trial and error as even they themself wouldn't be able to know how far the bed shifted. By the time we finished everything, 6 hours had gone by. We were very exhausted mentally and physically as we had run into many problems that we had to solve. At the same time, we were also thankful that we decided to start this project early so that we still had time to solve all those problems and didn't have to panic and rush.

Through this project, we had really learned a lot. Whether it is the functions of fusion 360 or how to operate the 3D printer. These were things that we have never come into contact with before. We must say that while it is tiring at times, ultimately when we finally saw the device being produced we were so proud of ourselves. This device is something that we had make from scratch, from start to finish.