Generating the idea
When we were first discussing the midterm project, Sarah and I knew we wanted to design a relatively simple but fun mechanical model. We initially wanted to base our model off a merry go round, but that already existed and we wanted to be unique. Following the amusement park attractions theme, we then thought about making a m i n i a t u r e t e a c u p r i d e.
We both immediately thought this is the one.
Before starting of course we asked about the feasibility of this project and concluded that we would use the mechanical movement n°24.
Our First Drawings…
After a lot of talking and brainstorming of ideas on how to make our tea cup ride, we started to draw these ideas out to have a visual representation of what we were saying.
We found a video of a model very similar to what we wanted to make:
One of our first drawings of our cups and inner gears
Our original idea was that we would have around 6 tea cups on a plate that is spinning and the tea cups would be spinning on themselves as well.
The tea cups would be attached to a small dowel that would itself be attached to a small gear that would spin the cups by moving along an inner gear placed underneath the upper plate.
One of the first designs for the inner gears
We also planned to have a bigger gear underneath the plate with the inner-gears that would spin the upper plate (the one with the tea cups on it).
The design in the figure above would have definitely not worked since having two dowels would make the inner gears spin and the plate spin but the cups would stay still.
Looking back on this drawing after completing our project, we decided to change quite a few parts along the way. I think we were being a bit ambitious with the amount of teacups that could fit on our ride. Also, we found it difficult to find a way to make the tea cups have slanted sides so we decided to make them resemble open cubes.
Here is what our must updated drawings look like:
Drawing for the upper plate
Drawing of the whole mechanism with the upper-plate, inner-gears and bottom plate along with the crank.
Low Fidelity Prototype
Stage 2 of the mechanical model process involved testing our drawings out by using cardboard to create our model. I thought this stage was really helpful for us, especially because we got to notice areas in which our model does not function properly.
Our upper plate made out of cardboard
Sarah and I waiting for the wood glue to dry. We put whiteboard markers between the upper-plate and and the second plate (the one with the inner gears) so that our upper-plate will not be tilted
The first time we constructed our cardboard prototype, we did not use the laser cutter and only used rulers for measurements, which made them a bit un-precise. The second time, we used the laser cutter which made our design look a lot better.
We noticed that the upper plate was tilting a lot, as well as the cups attached to the smaller gears. This made the whole system difficult to operate and the cups weren’t spinning smoothly. Also, our bigger gears were very thin and had to be aligned almost perfectly for the plates to spin.
After discussing these issues with Dr Wettergreen, Rafe, Rachel, Luke and Hayden, we took the following notes.
We had a list of questions to ask during the second check-in. Then we wrote future changes we would make with our model made out of wood to avoid it from encountering the same issues as the one we made out of cardboard.
Medium/High Fidelity Prototype
Instead of cutting 6 cups, we decided our teacup ride was only going to have 3 cups to reduce the amount of complications. This meant we also had to reduce the overall size of our model, which is why we modified our files on adobe illustrator that we used for our low fidelity prototype. Our upper plate initially had a diameter of 14 inches but we found that 11 inches was enough for 3 cups.
We started by using the laser cutter to cut our gears, cups and plates. We wanted to include bearings in every hole that had a spinning dowel in it but weren’t sure about the sizes of the dowels we ordered so we started by cutting the gears that were not going to have bearings. Also, to avoid the dowels from tilting or the plates from being slanted, we added a few washers with different inner diameters (depending on the diameter of the dowel it will be going into) around the dowels.
the adobe illustrator file that we used to cut most of the parts of our model
Another issue Sarah and I were constantly trying to fix was reducing friction as much as we can. One of the ways in which we were trying to accomplish this was while making the smaller dowels (that were attached to a cup and a smaller gear). I found this process to be particularly complicated because we had to be very precise. We wanted the cups to levitate a bit so that friction between the cups and the upper plate would be reduced and we also wanted the smaller gears to levitate a bit. This meant we had to sand the small dowels by the right amount.
Only the part of the smaller dowel that was sanded is sticking out of the cup
At first we sanded each of these dowels by hand, and it was very un-precise. I then used the drill press which made sanding a lot easier. I think that some of the dowels are sanded more than the others which causes differences in the heights of the small gears or cups.
Here we were finally starting to see what our model was going to look like!
For the metal component of our project, we decided to use the water jet cutter to make an aluminium handle.
We changed the design of our handle, which was rounder in our medium fidelity prototype. The handle ended being a bit thicker than anticipated, but at least it allows us to grab it more easily. Also, I think the hole in the handle for the dowel was cut last, which made it not very round. We had to drill the hole with a special machine again for it to be rounder.
Our handle after the sanding
Although the handle was secure enough after we hammered it in the dowel, we added a lot of super glue to make sure it wouldn’t detach itself from the dowel. This made our handle look a bit ugly since there was super glue everywhere. That’s why we sanded the top of it afterwards which makes it look shinier now.
Last Modifications
We ended this whole process by treating the aesthetic part of our project. We created three different vinyl designs for our cups to make them look nicer.
We printed each design four times to stick one on each side of each cup
After sticking the stickers onto the sides of our cups, we spray painted each cup a different colour and let the paint dry. We then took the stickers off.
Also, we made sure each of our dowels were sanded enough so that it looked like they blended into each plate. After we glued all of the parts together, we applied oil on the wood.
F I N A L M O D E L
After putting everything together, we noticed that the plate the handle was on was a little offcentered. I think this was because the dowels that held the bottom plate and the handle’s plate were a slanted which shifted the plate.
Also, another area of improvement would be aligning the bigger gears better. We added a washer underneath one of the gears which made it slightly more elevated than the other. The other gear was initially higher because of the bearing we put under it.
Here we can see how the two gears are not perfectly aligned with each other
Although we definitely made a lot of technical mistakes along the way, I’m still really proud about how our model turned out! I remember seeing all the previous midterm models when I first started to work in the OEDK and being so impressed by them. I’m really glad I could learn how to produce something similar.
Cost
- 5 wood sheets: $8.99 (Amazon)
- 2 cardboard sheets: $11.66 (Amazon)
- dowels: $4.66 x 2 (Home depot)
- spray paint: $6.48 x 3 (Home depot)
- superglue: $5.68 (Home depot)
- wood glue: $7.98 (Home depot)
- adhesive vinyl sheet: 4.25 (Expressions vinyl)
- labor: 30 x 7.25= $217.5
TOTAL: $284.82
