3D printing entry

My design for the 3D printed object will be a shaker toy that has a round sphere in the middle of a cuboid shaped object.

This shape is not easy to make using conventional methods such as cutting or boring of the object because;

1) there is a spherical object within the hollow cuboid solid.
2) the holes on all 6 sides of the cuboid solid are smaller than the diameter of the spherical object within the hollow cuboid solid, which means that they cannot be constructed separately and pieced together afterwards.

Hence, I have decided to construct this using a CAD program such as Fusion360, and then using Cura to slice the object into layers for 3D printing.

First, I create a new component and constructed a square, 20mm by 20mm on a new sketch on the Fusion360 program.

Next, I extruded the sketch that I have created and formed the square into a cube, now 20mm by 20mm by 20mm.

I then shell out the inner portion of the cuboid by using the shell function in the solids tab, creating a ‘hollow’ cube. This action can also save time if you were creating a normal cube, however as the inner part of the cube is now hollow, it may sacrifice the structural strength of the cube in the process.

To show that the cube has a spherical ball in the middle of it; I cut 6 holes into all the sides of the cuboid shape as shown below. There is a hole in the centre of each square face on the cube that is the same thickness as the cuboid shell, 2mm. Each hole has a diameter of 10mm.

Then, I created a new component and put in a sphere under the solids tab. The diameter of the sphere is 12mm. This means that the sphere will not be able to come out of the shell of the cuboid solid through the holes constructed in the solid.

Putting the two components together, this is the product of the solid I will be 3D printing. As you can see, the spherical ball is visualised to be inside the shell of the cuboid solid.

To allow the 3D printer to recognise and start printing the solid from PLA filament, I must first upload the .stl file of my CAD product into Cura. Cura will enable me to choose the 3D printer from the machine library, and set my desired settings of layer height, amount of infill, bed adhesion as well as quality of print. Since I was using the Creality Ender 3 printer, I ensured that I selected the right printer and proceeded to change my settings for my product.

I removed the bed adhesion, amount of infill and set the layer height to 3mm. This was the product simulated on the Ender 3 printer. I proceeded to add in the supports for the product, and then sliced my product to produce the printing layers. The button ‘Save to disk’ allowed me to save my creation into a GCODE file, which the printer will read and then print as in the simulation below.

This is one of the images of the 3D printer in operation. You could see the nozzle head printing out the PLA filament on the bed of the Ender 3.

The video showing the 3D printer nozzle printing the PLA filament on the bed is seen below:

 

The product of my 3D printed creation is shown here:

This was after a few attempts to remove the small excess pieces of PLA stuck onto the product during printing of the support for the spherical ball. This proved difficult to remove despite the support being produced to print at only 50^o of overhang. Minimal support was used to produce the sphere solid within the cuboid solid, yet the base required manual work to remove excess pieces of PLA that were stuck onto the sphere solid after most of the base was removed.

The top part of the cuboid had many loose strands of PLA in different directions due to the lack of supports for the top surface of the cube as shown in the picture below:

In order to remove the loose strands of PLA, I had to carefully cut and mill away the excess, in case I break the cuboid solid by using too much strength.

 

Lastly, the original design files for 3D printing (both .f3d and .stl files) are below here:

The .f3d file:

The .stl file:

3D printing model (.stl)

Reflection:

In my opinion, 3D printing is a great tool to use, especially for constructing very interesting creations that may be difficult to construct using conventional methods of subtractive manufacturing. However, there are limitations to 3D printing, one of them being the quality of the design. One such example I could give during the process for my current shaker toy creation is that the 3D printing for the top layer of the cuboid shape was almost unsuccessful due to the overhang when the printer is printing the ceiling of the cuboid. This caused the loose strands of PLA hanging over the sphere as shown in the images above; when the printer attempted to print the ceiling in mid-air. Despite numerous attempts to change the support settings, the printer could only print the support for the ceiling from the print bed; and since the sphere was in the way, the printer was unable to print the support for the ceiling.

To perfect the creation, I also had to make sure I properly ironed out rough edges of the corner during the printing and cut and peel any unwanted strands of PLA that were jutting out of the solids. Hence,I feel that conventional methods of subtractive manufacturing cannot be completely phased out even though additive manufacturing like 3D printing is more advanced.