I was working with a grade 1 class and they were learning about potential and kinetic energy. The students had recently visited The Tinkering Studio at the Science Centre here in Singapore and a teacher commented on how much the kids enjoyed the pinball table there. She asked me to make her one.
I had done a project with another class where students made a sort of a pinball machine using nails and rubber bands, but I liked the way that this table allowed for kids to put whatever sorts of obstacles on there that they liked.
We are a bit tight on space however, so this would have to be something that could be easily set up, but then easily put away. I decided to use PVC since it would be light and easy to hang on the wall or slip behind a cabinet or bookshelf. Like the one at the Tinkering Studio, kids can make up their own games and change things around however they like.
This is the Mark I, because I would like to make a new one with flippers when I get the chance.
Step 1: Step 1; What Do We Need?
The PVC pipe that I used for most of this project was 1" (outside diameter). I'm sure I could have used something a little narrower or a little thicker but I already had this in the room.
To make the plunger, I needed a second diameter of PVC that would slide through the first. The internal diameter of my 1" PVC was 7/8" and I was lucky enough to find a piece laying around that fit snugly inside. With just a bit of sanding with a fine grit sandpaper, it slid back and forth through the larger pipe pretty well.
I used two 90° elbows for this project. One for the larger diameter pipe that made one of the corners of the frame and another for a handle on the smaller diameter pipe that would become the plunger.
I used a heat gun to shape the PVC into a curve. The fan cover that you see in the picture was just to help me get it nice and round as I shaped it.
I used hot melt glue as my adhesive. When I do the next one, I will probably use a two-part epoxy so it looks a bit nicer. If you look closely at the pictures, it's a bit gunky in places.
Finally, I used a bit of a dowel, a couple of screws and some elastic bands for the plunger mechanism.
Step 2: Step 2: Bending the PVC
When heated, PVC pipe can be shaped very easily. A quick search online will bring up thousands of fantastic projects that people have done by heating and bending PVC into all sorts of things. It can be done with a hair dryer that has a higher wattage, although a heat gun is probably the better choice.
I laid the pipe on a board that was about the size I wanted for the finished product. I did this for two reasons. First, I wanted to protect the table from the heat and second, it gave me a couple of straight edges to ensure that the finished piece was square. I used the fan cover as a jig to get a nice curve. You just need something round that's got the same diameter as the width of the table that it will be sitting on.
When I bent the PVC, I just took my time, heating it slowly, giving it a little bit of a pull and then heating it some more. I didn't have any problems with kinks appearing in the pipe, but this can happen if the pipe gets too soft and you bend it too quickly. Some people recommend filling it with sand first and in this Instructable, he slides a drain auger into the pipe to help it keep it's shape. It's probably worth the extra time and effort to do it this way. I just didn't think of it at the time and luckily, mine turned out OK.
Another popular way to bend PVC is by putting a piece of tape on the end and filling it heated sand, which can be done in the oven or on the stove. This should also help ensure you don't get kinks in it as it bends. There is a nice video on the Darbin Orvar Channel on YouTube to explain this technique and she has built a simple jigs to help bend the pipe into a variety of curved shapes. If I were doing anything more complicated than just a simple curve, I would certainly do it like this.
**Please note that when heated, PVC releases a number of dangerous chemicals into the air. You can learn more about which chemicals are released and their effects here. Be sure to work in a well-ventilated space and wear a mask when doing the heating and bending for this project.
Step 3: Step 3: Finishing the Frame
I added the 90° elbow and another piece of pip across the bottom of the frame, leaving enough of a gap to put in a piece of pipe that would become the sleeve for the plunger. I used a half-round file on the end of the pipe to get a nice fit and glued it together with hot glue. Then I put another section of pipe next to the plunger sleeve, again, filing down the end with a half-round file to get a nice fit. This piece helps hold the plunger sleeve in place and is part of the mechanism to get it to snap back when you pull it.
The popsicle sticks that you see in the picture (tongue depressors, actually) are spacers because the marbles that I have are also 1" in diameter. I needed a tiny gap for them to be able to roll in and out.
Step 4: Step 4: the Plunger
The plunger is a piece of 7/8" PVC. With some light sanding with a fine grit sandpaper, it slides back and forth very easily in the 1" pipe. I put a 90° elbow on the end of that as a sort of handle and glued a bit of wooden dowel into the other end that will strike the ball.
I put a couple of screws into the pipe on either side of the plunger sleeve and put a hook into the handle. Then I attached some elastic bands and it worked like a charm, snapping back nicely when released.
Note that the piece of pipe that is the sleeve for the plunger needs to be a little bit shorter than the pieces on either side. This will create a slot for the ball. You can see what I mean if you watch the videos in the next step.
Step 5: Step 5: Play!
The machine just sits on a tabletop. A little Blu Tack will help keep it from sliding around. Add a couple of blocks under one end of the table to create an incline and you are ready to go.
We left it up to the children to find things from around the classroom to make the game more interesting to play. A few bells from the dollar store made a nice addition, but simple blocks worked great too.
I hope you find this Instructable helpful. If you make one or you think of ways to make it better, please comment!
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