STEM project: Auto-fill water bowl
Air pressure and its effects
Creating components of a product with 3D printing technology
Designing a product that is safe for pets
Capacity calculation
If you are a pet owner, then you should be no stranger to this difficult situation: you need to be away for the day, but you do not want to leave your pet thirsty or drinking dirty water. But no longer! There is an economical way to provide fresh water to your pet as required.
Just follow a few simple steps to build an auto-fill pet water bowl. The bowl can hold a medium-sized plastic water bottle and automatically release water from the bottle when the water level in the bowl is low. It is a perfect solution to the problem of providing enough clean water for your pet to drink. The bowl is large enough for a cat, small dog or rabbit to drink comfortably.
Before you decide to get a pet, ask yourself the following questions. Do you have enough space at home for a pet? Are you willing to take time and effort to look after your pet? Can you take care of it properly? One more thing: you can help animals in need by adopting a pet instead of buying one.
Check out this website for more information on pets: www.pets.gov.hk.
Punch a small hole near the mouth of a plastic bottle of water. Then invert the bottle in a water-filled bowl or big bottle. Will the water in the bottle leak out? The answer is no. But why?
At the beginning, the pressure inside the small bottle is (1) the air pressure outside the small bottle, so the water will leak from the small hole at the bottom of the small bottle into the big bottle.
After a while, the leaked water will make the water level of the small bottle drop, which will make the pressure inside the small bottle decrease. Until the pressure inside the small bottle is (2) the air pressure outside the small bottle, the water will stop leaking out.
| 1 large plastic bottle* | |
| 1 small plastic bottle | |
| iron wire |
*The bottle should be big enough for the small bottle to be put inside it.
| scissors or box cutter |
Be careful using scissors or a box cutter. You don’t want to injure yourself!
Pick a larger bottle if your pet needs a lot of water every day!
- cage
- open
- invert
- draw
- hole
- fill
- place
Use a marker pen to _________ a rectangle on one side of the large plastic bottle.
Use scissors or a box cutter to cut along the lines of the rectangle, so that the large bottle is cut __________ on one side.
Cut a small __________ near the mouth of the small plastic bottle.
__________ the small bottle with water (leaving some air inside) and _________ it into the large bottle.
Use a rubber band to hold them in ________.
Use iron wire to attach the device to a _________ if necessary.
I think you should add a label holder on the stand. You can write dates on labels to remind yourself to wash or change the water bottle regularly.
I have an idea. Why don’t you add markers on the bottle? You can then check how much water your pet consumes every day and see if it is using the bottle properly.
- No stranger to a situation – familiar with a situation
- But no longer – not any more
- A perfect solution to – the best way to (solve a problem)
- To take time and effort – to spend time and try hard (to do something)
If 3D printers are available at your school, you can download a free 3D printing model from here.
3D printing model
A suitable cap shape
How to use
Import the downloaded model.
(File > Import > Stl)
Create a ‘text’ object.
(Create > Other: Text)
Put the ‘text’ object on the bowl.
If your dog has weak hind legs, or if your dog cannot use its hind legs and is unable to walk, a dog wheelchair is the answer to the problem! You can make a simple dog wheelchair with 3D printing. You can click here to learn how to build a dog wheelchair with 3D printed components. You can also make a sample dog wheelchair model with following materials and this 3D printed toy dog.
A 3D-printed scale model
A dog using a wheelchair
| 4 bendable drinking straws | |
| 2 plastic bottle caps | |
| strings or ribbon | |
| iron wire |
| scissors or box cutter | |
| awl or screw driver | |
| safety gloves |
Be careful using scissors or a box cutter. You don’t want to injure yourself!
Use scissors or a box cutter to cut the 4 straws into 6 pieces as shown.
Use an awl or a screwdriver to make a small hole at the centre of each bottle cap. The caps will be used as the wheels.
Use iron wire to connect the straws as shown. You can use an awl or a screwdriver to make holes on the straws for connecting the iron wire.
Use iron wire to connect the caps as shown.
Put the 3D printed dog model on the wheelchair.
Use a piece of string or ribbon to hold the 3D printed dog model on the wheelchair.
Search the Internet for innovative pet products. Pick one that you find most interesting and tell your classmates about its design, use and effectiveness. Here are some relevant information and websites:
- Ball thrower
- Auto feeder
- What is your choice and its use?
- Why you think it’s cool?
