Follow directions exactly when making your first engine!
And don't do anything not in the instructions. Trust me that there are reasons for all the finicky details. --Slater, the sciencetoymaker
If you haven't yet, first watch how to follow the steps in the instructional videos. (Part 2 at 3:29).
Below are the video links and descriptions to making the kind of toy steam engine boat seen in the movie Ponyo. You can go straight to the instructional video play list, if you want.
Introduction: Putt Putt Boat introduction in two parts
Part 1 Introduction to pop pop (aka putt putt) boats.
Part 1 shows my students testing their boats and gives an overview of the steps involved in making the engine out an aluminum beverage can. I relate where I first encountered pop pops (in South Asia in the 1980's). Then on to a little history: of steam power in general and putt putt boats specifically. Next I show some commercial boats I bought.
I start off relating my efforts to create an easy enough for my students to make, inexpensive steam engine that used common materials that could be found anywhere. Then I make my plea that people follow the directions carefully for the first engine, then experiment.
Materials and Tools (video Part 3): Materials and Tools for a Putt Putt Boat
Part 3 goes through all the materials you will need.
Note that if you would rather use an oil lamp instead of a candle, excellent oil lamp instructions are here.
Build the Boiler
Step 1 (Video Part 4): Cut off Can Top
Part 4 is Step 1 of the actual building instructions. Are you confused enough? Sorry! The steps are small. This Step 1 is just cutting off the top of an aluminum beverage can.
Step 2 (Video Part 5): Cut and Trim Can Middle
Cut and trim the middle part of the can so you have a sheet of aluminum to build the engine with.
Step 3 (Video Part 6): Fold Aluminum Sheet in Half
Fold the aluminum sheet in half, with a thin sliver of the inside of the can showing so it's easier to separate in a later step.
Step 4 (Video Part 7): Scale Check. tape Pattern on
Print out the pattern to actual size (no fitting to page or scaling) and check the scale of the pattern to be sure. Then you tape the pattern onto the aluminum sheet. Save the other boiler pattern and that other weird-looking pattern called the bend pattern.
Step 5 (Video Part 8): Cut Solid Line, Write Name
Cutout the pattern and aluminum on the solid lines--carefully. Save one of the aluminum strips for a later step. Oops, I noticed that the pattern here doesn't have the writing--that's ok, same pattern.
Step 6 (Video Part 9): Fold Dashed Lines, Sharp Corner
Find a sharp corner, line up the dashed lines with the corner, and make clear fold lines on the dashed lines of the pattern. Your thumbs should be together, and press really hard so you see clear fold lines.
Step 7 (Video Part 10): Fold Edges All the Way, Flatten
Taking all the pattern/tape off and accurately fold the edge flaps the rest of the way over with a credit card or something like it. Then you need to pound it (not rub it) flat. Be careful not to kink it.
Step 8 (Video Part 11): Straw Parts Names, Open, Long end of Straws in
Use a thumbnail to open up the end of the "pocket" a bit, then pinch the end of the long part of a flexible straw and push it in. Then the long part of another straw. Push all the way in, but not so hard them split the other end.
Step 9 (Video Part 12): Small End Straw in, Tape Card
Put one more straw in to form a curved dome top, but this time it's the short end of of a straw. Pinch it and push it in--on the side with the flaps--only to the bendy part. Then put tape donuts on the flat side without the flaps and tape it to a piece of cardboard. Gently push on the edges to make the bottom flat.
Step 10 (Video Part 13): Mix, Apply, Push in Glue
Actually glue the aluminum so it keeps its new shape. You should watch the whole step before starting because you only have 5 minutes once you mix the two parts together (less if it's hot). You should have equal parts and mix thoroughly. Dab it on the silver parts even where the silver disappears, especially the ends. It's really important to push the epoxy in between the folds of aluminum with the strip, for strength and to prevent leaks. GOOD NEWS NOT IN THE VIDEO YET: Sticky epoxy is easy to get off with VINIGAR.
Step 11 (Video Part 14): Measure, Cut Glue in Straws
Measure 1 1/2" or 39mm from the end of the bendy part of the straws into the small part of the straw. Cut there and apply mixed up, thin, even layer of epoxy to the small part of the straws, but not within 1/4" or 6mm of the bendy part. Put the straws in the end of the aluminum, but only to within 1/4" or 6mm of the bendy part. If a lot of epoxy gets on the bendy part, wipe it off, both above and below.
Step 12 (Video Part 15): Seal Where Straws Go in
Be careful when handling the engine and mixing up a tiny bit more epoxy and using it to seal off the 3 or 4 holes where the straws go into the engine.
Step 13 (Video Part 16): Pressure Test, Seal Leaks
Take a tip from automotive people and use pressurized air into the straws to find leaks (bubbles in the water). Patch with epoxy and don't pressure test again until it is hard. Use hot water if you need to speed up the epoxy
Step 14 (Video Part 17): Make Angle Tool
Make a cardboard angle tool to set the angle between the aluminum boiler and the straws. You saved the pattern that printed out with the boiler pattern way back in part 7, step 4, didn't you?!
Step 15 (Video Part 18): Tape Engine to Angle Tool
Pull the straws longer and tape the angle tool to the boiler and straws. Make sure the folded-over edges are facing outward, not inward against the angle tool.
Step 16 (Video Part 19) : Glue Bendy Straw Part
Use one of the cooler kind of hot glue guns to apply a thin layer of hot glue over the bendy part of the straws, so as stiffen them so they hold the correct angle.
Candles and Candle Holder
Step 17 (Video Part 20): Cut Candles, Make Holder
Cut down thin birthday candles into 4 pieces, then make a candle holder out of aluminum foil. It's important to push the aluminum down to the base of the candle, or the candle will go out before burning most of its wax.
Note that a sharp viewer has created some great instructions for making an oil lamp instead of the candle for heat.
Powered Engine Test
Step 18 (Video Part 21)
You finally get to power test the engine! You don't need a boat to power test the engine. You must prime the straws every time you use the engine. And the first time you use the engine you should slosh some water around inside the engine so the little droplets of water can flash to steam and get your engine going. To start out put the candle flame in the middle between the front and the back of the engine.
Step 19 (Video Part 22) (Skip This Step If Your Engine Works)
Troubleshoot if your engine doesn't work. SKIP THIS SECTION IF YOUR ENGINE WORKS OK. Sometimes you only have to prime the straws with water and try it again and it works. Or maybe you need a more heat if you are using a tea candle (don't use a lighter or you'll ruin the engine). Sometimes there might be a leak even though you already tested it. Still, it's not hard to find it and seal the engine. Sometimes the cause of the trouble remains a mystery and you might just have to make another one (Yep, I know, I thoroughly hate having to do things over too).
Post Test Tips, Boat Decision
Step 20 (Video Part 23)
Some tips when you're finished using the engine, like wiping off the carbon from the candle. Also, using heat to remove what's left of the candle and affix a new one so it doesn't keep falling out. Now is the time to decide which kind of boat to make for your engine. Instructions for the simple foam boat are in Part 24. But the instructions for the 3D milk carton boat are in Part 27, farther below.
Make a Simple Flat Boat
Step 21 (Video Part 24)
Make a simple flat boat out of a foam grocery tray. It's only held on with rubber bands, so you can move the engine to another boat later if you want. Funny, but it seems you actually have to put some weight to give the engine something to push against or the engine doesn't work well.
Make the Boat Faster
Step 22 (Video Part 25)
Make the boat go faster by restricting the straws a little at the end, just like real jet engines and rockets. Finally you can tell the control freak (me) to go soak his head, and you can break loose with experiments.
Step 23 (Video Part 26)
Congratulations and some final words. I depend on feedback to make the instructions better. And frankly, when you get the engine working it's encouraging to me to hear that as well.There is a gallery of pictures of people's pop pop boats that you can add your boat to. Also, now that you have made a boat, be aware that there is a Yahoo group of people from all over the world who experiment and talk about pop pop boats. Some people are just interested in engine development, or scaling up engines, others in making a beautiful boat for the engine, others in the history. There are nice people moderating the group, there is an enormous archive of tips and pictures, there is no money involved, and it's easy to join (if an internet dummy like me can do it, anyone can). And, we are mostly older people, but I think I can speak for the group that we would be thrilled to see the work that younger people are pursuing (and you are still welcome if you are a geezer like the rest of us).
Extra: Hull, Deck, Cabin and Rudder
Make a 3D Hull
Part 27 is making a 3D hull from a milk or juice carton.
Most of the video is from a video I made for my students years ago. This hull is made from a 1/2 gallon or 2 liter milk or juice carton. That kind of cardboard is waterproof, east to cut, bend, glue and paint. Make sure that when you print the pattern you do not have any box checked that "fits to page" or otherwise changes the scale. After it's cut, it's folded and fastened with staples and hot glue.
After it's widened you can install the engine. The straws go out a hole in the bottom, so you seal and glue in the engine with hot glue.
If YouTube is blocked at your school, try the SchoolTube equivalents below.
If you want to watch one long video instead of 3 separate parts, you can watch the whole video here.
If blocked, try this SchoolTube equivalent of Part 27A
If YouTube is blocked, try this SchoolTube equivalent of Part 27C
Make a Rudder
I got a wonderful tip about making a rudder for the boat from young Australians Elana (12) and Alex (10) who made putt putt boats with their grandad Les. Click here to see the PDF of the drawing of their ingenious rudder system.
Make the Deck and Cabin
This too is made from a milk or juice carton. It fits on top of the hull but comes off if you need to get to the engine. The PDF patterns for the deck/cabin assembly are here. (You don't have to make the smoke stack, but the instructions for that are also here if you want to.)
A hot glue gun puts all the pieces together.
Now that you've made an engine, hull and deck, check out the work of a true craftsman, my friend Daryl from Canada