Hannah's Assignment 4: Moving Parts

Design

My idea for this assignment was to make a pinwheel of 2 parts: a stick and a flower. The stick is the non-moving part while the flower is the moving part. The two are assembled using a plastic rivet. My plan was to 3D print the stick and to laser cut the flower. Once assembled, you can spin the flower mimicking a pinwheel.

Process

Step 1: Creating parts on OnShape
Once I knew what I wanted for my design, it was time to create the 2 parts. I first started by creating the stick. I created a new document and clicked on sketch. I used the line tool to create my rectangle shape. I used the dimension tool to adjust the size of the stick. I wanted it to be 7 inches long and half an inch wide. I then exit sketch to start a new sketch to make the hole in my shape. I added a circle to sketch 2 then tried to figure out how to subtract the circle shape from the rectangle. With Lukas' help, he told me to actually make the 2 shapes in one sketch. I deleted the circle sketch and re-opened the rectangle sketch. I added a circle on top of the rectangle. To make sure I had the right dimension for the hole, I opened up Joshua's plastic rivet OnShape file. I measured the widest dimension of the part of the rivet that would go in the stick. I used that dimension for the diameter of the circle. I adjusted the diameter of the circle using the dimensions tool. To achieve the curves on the stick, I used the fillet tool. Happy with the sketch, it was time to extrude the shape. I extruded the shape to be .5 in tall.

Stick part made on OnShape

Now it was time to work on the flower. I started a new document to make the flower part. I clicked on sketch and used the spline tool to make the flower. I first used spline to design the entire flower, but I wanted the flower to be a little more symmetrical. Lukas suggested using the spline tool to make one petal then use the mirror tool to mirror the petal to the plane I wanted it. Mirroring gave me a symmetrical shape, and that's what I did. Then I used the same circle dimension from the stick to add to the flower as the plastic rivet would be put through the flower and stick holes. Once I was done with the sketch, I extruded the shape. Knowing I was going to laser cut the flower and how thick my cardboard was, I extruded the thickness to .1 in.

Flower part made on OnShape

Step 2: Creating an assembly
After finishing the flower part, it was time to assemble! I used the plastic rivet Joshua designed on OnShape to piece the flower and stick together. I imported each part: stick, flower, and plastic rivet. I put the stick in a fixed position. Then using the pin slot mate, I connected the hole of the flower to the hole of the stick. I had to offset the flower shape a little bit so that it wasn't going through the stick. I then used the revolute mate to put the rivet through the flower and stick. I tried moving the flower, and it worked! This made me confident about my design.

Parts assembled on OnShape

Step 3: Exporting
After seeing my parts assembled and happy with the results, I exported my files. I exported the stick to an STL file to 3D print, and the flower to a DWG file to laser cut. I had issues with the STL export. When I opened the file on DigiLab, nothing appeared. Inside the printer preview was blank. I tried different view options and nothing.

STL export from OnShape didn't appear in DigiLab preview

I went back to OnShape and exported the stick to a Rhino file. The stick appeared in the Rhino file and then I exported into STL. This time the STL file exported from Rhino appeared on the DigiLab 3D print preview platform.

Exporting to Rhino from OnShape first and then exporting to STL worked

Fortunately for the flower, I was able to open the DWG file on Illustrator with no issue. I just made sure to convert the size properly using the measurements I used on OnShape which was millimeters.

Step 4: 3D Printing
I went to the MILL on Friday morning to start 3D printing. I rotated the stick on DigiLab to make the hole flat to the platform, so that I wouldn't have to use support for the hole. I checked the print settings then prepared and saved the file to my USB.

3D Print Settings

I then went to find an open 3D printer and changed the filament using the same steps I did for the last assignment. Once the filament was ready, I used glue stick on the platform and was ready to build. I copied the file from my USB to the printer and started the build.
The print started off with no issue. However, towards 3/4 of the way through, the filament got tangled, and the 3D printer was making a sound. I saw someone at the 3D printer I was using and walked over. She was the one who informed me of what happened and paused my print to fix the issue. Once the filament was untangled and the print restarted, the machine's callibration became off. It moved the print over by a little bit. Seeing that this was going to become an issue, I stopped the print and decided to restart.

3D Printing Fail

Step 4b: Iterate stick part & 3D printing again
Before restarting the print, I took the stick and tested to see if the plastic rivet would fit. The hole of the stick was a little too big. I had measured the rivet on the design Joshua created on OnShape instead of using my calipers to measure the actual rivet. I found calipers at the MILL and measured the rivet at its biggest diameter for the part that would go through the hole fo the flower and stick. Using this measurement, I adjusted the diameter of the hole on the stick on OnShape.

Adjusted diameter on OnShape

I re-exported the stick file to Rhino then to STL (to avoid the issue I was having from exporting straight to STL from OnShape). I double checked the settings on DigiLab, saved the file to my USB, and restarted the 3D printing process.

Exporting for 3D printing

I did the same steps as before when it came to setting up the 3D printer and starting the build. I stayed by the printer at the beginning to make sure nothing goes wrong.

The print started off well, so I went to my computer to update the flower to laser cut. Less than an hour later, the print finished, and the stick turned out as I wanted!

3D Printing Stick

Step 5: Edit flower part & laser cutting
When I had to adjust the diameter of the circle on the stick, I knew I had to adjust it on the flower as well. I wanted to fix the diameter on OnShape before laser cutting the flower. I used the same diameter for the hole of the flower as the hole of the stick.

Adjusted diameter on OnShape

Once I readjusted the measurement on OnShape, I exported the flower part into a DWG file. I opened the file with Illustrator. A pop up appeared on how I wanted to scale the image. I chose 1 unit to 1 mm because the measurements on my OnShape was in mm.

DWG to AI export

I decided to make the flower shape a little bigger because on OnShape the flower got smaller when I readjusted the circle diameter. I made the flower shape bigger on Illustrator. Once I did that, I adjusted all the strokes to 0.001 pt to be able to vector cut with the laser. When I was ready, I went to the laser cutter and did the same process as I've always done when laser cutting.

Laser cutter settings

Laser cutting

Step 6: Putting it together
Now that the flower had been laser cut, it was time to put together! I put the flower part on top of the stick, lining up the holes then put the rivet through. I spun the flower, and ta-da! It was a success!

Parts assembled!

Peer Teaching: Lukas S. for helping me with OnShape
Additional Sources: I used Joshua's OnShape file for the plastic rivet for the assembly.