Cat Shaky Fidget

Lesson Plan and Constraints:

The goal was to create a 3D printed object with multiple inner layers that could shake and move around without falling apart.

• All designs must be made from an initial shape, which is then offset numerous times, then extruded and cut to make a shape with smaller versions of the shape inside
• They must fit into a 8 cm by 8 cm square and the height must be 1 cm tall
• All cuts and extrudes must have a draft (this means angled inwards)
• Must not require ANY supports, (no supports).
• NO moving parts, (no gyroscopes, fidget spinners, etc.)

Summary & General Advice:

My object is a simplified version of a cat head that was offset 32 times to make 16 layers to shake. Since it is a fidget, I wanted it to be something that I liked, so I chose a cat because they are cool.

The offset tool plays a large role in this project, so I recommend being familiar with it before you start.

Overview:

To start off I looked for a simple outline of a cat, and Hello Kitty happened to work well for this because of her simple shape. Next, make a constraint box, mine was 7x8in.

The next step was importing the image into Solidworks to trace over to make the whole process more efficient. Adjust the image so that it fills the box. Using the arc tool, trace over the image until its fully outlined

Then you’ll delete everything except for the sketch outline that you just made. Offset that outline, making sure to select reverse in the drop down menu on the left hand side, until it is filled. The distance between the offsets should be 0.1 cm. Once you are done, it should look like the image below.

Save that sketch, and select the outermost offset. With that selected, in the features tab change hit boss extrude. I used 25 degrees for the angle, and 1 cm for the height. You can adjust these numbers as you like as long as all cuts and extrudes are the same. There is a chance though that it will not work if you mess with the numbers too much. It will look like the image below, do not worry, it’s supposed to look like that.

Now, you want to click the next line after the one you just extruded. You’ll have to manually turn on the sketch so that you can see it. Use the extrude cut tool, and make sure that you reverse the direction of it so that it’s cutting through the object. Also change “blind” on the left side of your screen, to “through all”. This angle will be set to 15 as well, and save.

Now repeat these steps until you have the whole thing filled out. Once you’re finished it will end up looking like this. You want to be able to see through the center, it creates a better effect, and prints better.

Then all you have to do is mirror this over the front plane and you’re done.

Design Choices:

One of the first changes I had made to the project was deciding not to include the whiskers or the bow in this print, it would just make a better end result. Then the size I chose for the constraint bow was 7 x 8in because she wasn’t square. We also included fillets in certain areas to prevent the formation of super harsh corners when off-setting.

When extruding and cutting the offsets, ours had a small mistake here that we weren’t able to figure out the origin of or how to get rid of it. It had this weird little sharp thing that was going through a few of the layers. In the end we just left it as is because there was nothing we could do, and it didn’t affect the final print.

The first print came out fine, except for the innermost layer. It got messed up in the printing process, so we decided to delete those ones. You can decide to keep it or not if your printer is able to print it properly. We, however, got rid of it.

First:

Final:

The final problem we ran into was adjusting the angles of the extrudes. We wanted to change to something lower so the layers would fall out further, but when trying to do that we got an error message that didn’t allow us to go further. We were able to get here, but after that we had to stop. The angle we tried changing it to was 20. We were able to get down to 23, but no further. Since it was such a small change we scrapped the idea.