Before I start modeling and printing things, I need to establish the movement of the eye-pot.
Figure 1. Sketches of the eye-pot (Own work)
Sketching allowed me to think about possible movements and features of the teapot. One of the ideas I had is to move the lid on the pot up and down, releasing steam, and instead of walking, which I think will be too difficult for me to make, it is possible to create posable legs.
Teapot-lid
In my design, I expect the lid of the teapot to move linear, up-and-down. Usually, a linear actuator is picked for this job. Linear actuators are actuators that convert energy to forward motion. There is quite a range of mechanical actuators to choose from, but since they won't be able to connect to Autodesk Maya, it has to work with a servo.
Although servos have a rotational motion, it is possible to add additional linkages to convert this rotational movement to linear movement.
Rack and pinion
Figure 2. Servos converted to 3D-printed linear actuators
The previous image is a design of a rack and pinion posted by Cook (2019). The 3D-printed design holds a continuous rotation servo. Instead of a horn, this design uses a teethed gear. While the servo rotates, the pinion gear's teeth push the rack up and down, translating rotational motion into linear motion.
Cam and follower
The cam and follower mechanism is often used in engines. The follower restricted to a linear field of motion is pushed by the cam, converting a rotating motion to a linear motion. (See Fig. 3)
Figure 3. Cam and follower
The shape of the cam is called the profile. The profile dictates the rhythm of the up and down motion. (See Fig. 4)
Figure 4. Different cam profiles
To recreate this linear actuator, we could create a cam and attach it to a continuous servo. As the servo rotates, the cam pushes the rod up. The downside of this design is that we don't have much control of the animation unless we change the cam's profile.
Both designs use a continuous servo. Currently, the STFM-tool has only been tested using standard servos, which are limited to a 180-degree rotation. To use any of the mentioned linear actuators, we need to test if the STFM-tool accepts continuous servos.
Steam
Since the design we are working with is an angry teapot, it would be cool to incorporate some special effects in the form of steam. The use of smoke machines in amusement parks or theaters is nothing new. Usually, these machines are big and heavy while also requiring a large volume of water or smoke liquid. In other words, not meant to carry around.
This didn't stop cosplayers from adding smoke to their costumes and props. KamuiCosplay (2020) created a smoke machine with parts of an e-cigarette. This resulted in a battery-powered device that is small enough to be placed inside a prop and light enough to carry around.
Figure 5. E-cigarette smoke machine (KamuiCosplay, 2019)
The downsides to this DIY smoke machine are that it might run out of smoke juice fairly quickly due to the small container size. The device has a limited working time since it runs on batteries, and the machine isn't meant to continuously output smoke as it is easy to overheat.
In the video below KamuiCosplay shows you how to build your own smoke machine.
If you don't want to build your own smoke machine, you are not out of options. Although the use of smoke in costumes is fairly new, companies are coming out with smoke devices for this purpose. Spoonmakes (2021), for example, offers a range of smoke devices with interchangeable parts so that you can customize the device for your project.
Figure 6. CosCloud smoke machines
The smoke machines, however, are operated with a wired or wireless switch. This means that in order to produce smoke, we have to click a button manually. I wonder if it is possible to send a signal from inside Autodesk Maya to the Arduino to trigger the smoke machine. If this would be possible, we could incorporate the smoke trigger with the animation sequence!
Posing
As previously mentioned, I expect that I won't be able to make the teapot walk anytime soon. Instead of keeping the legs static, it is possible to pose them.
Posable figures are nothing new; think of a doll, for example. Since 3D printers exist, hobbyists have been creating articulated printable figures. Most of them don't even need to be assembled. The models are printed with just enough spacing between the parts so that they don't fuse together while printing but won't come apart either.
Figure 7. Articulated Fish Fossil 3D Printed Toy
The difference between dolls and the printed figures is that dolls are able to "carry" their pose due to friction, whereas the joints of the 3D-printed figures are moving freely in their socket. If there would be enough friction between the printable parts, it will be possible to have the figure carry its weight. However, I do expect that the parts have to be printed separately and assembled later on using screws so that it is possible to retighten the joint when there is loss of friction.
Focus
The outcome of the sketches resulted in at least 3 different functionalities with their own research questions. As the topics need additional research, which might take some time, it is decided to start prototyping with just the eye mechanism. The additional functionality of a moving teapot-lid is considered the highest priority of this functionality list as it comes closest to my main research.
List of figures
eye pot sketches
Cook, J. (2019a). 3D-printed linear actuator [Image]. Hackster.Io. https://www.hackster.io/news/hobby-servos-converted-to-3d-printed-linear-actuators-40fa4c9c81e2
Ryan, V. (n.d.). Cam and follower [Animatie]. Gifer. https://gifer.com/en/LNgW
Ryan, V. (n.d.-b). Cam profiles [Animation]. Technologystudent. https://technologystudent.com/cams/cam2.htm
KamuiCosplay. (2019, October 12). Smoke machine for costumes & props [Screenshot]. YouTube. https://www.youtube.com/watch?v=uDISX8MMLak&t=589s
spoonmakers. (n.d.). CosCloud [Image]. CosClouds - Cosplay Smoke Machine. https://www.spoonmakes.com/cosclouds-overview/
HFprototyping. (n.d.). Articulated Fish Fossil 3D Printed Toy [Image]. Etsy.Com. https://www.etsy.com/nl/listing/612897400/articulated-fish-fossil-3d-printed-toy
List of references
Cook, J. (2019). Hobby Servos Converted to 3D-Printed Linear Actuators. Hackster.Io. https://www.hackster.io/news/hobby-servos-converted-to-3d-printed-linear-actuators-40fa4c9c81e2
KamuiCosplay. (2020, January 16). I’ve build a SMOKING and LIGHT UP demonic mace! [Video]. YouTube. https://www.youtube.com/watch?v=DUk8I8gRHRE
spoonmakes. (2021, February 7). CosClouds Cosplay Smoke Machine. https://www.spoonmakes.com/cosclouds-overview/
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