In its new pocket-size format with a rubber-band closure, Rubber Band Engineer: All-Ballistic Pocket Edition is a fun-filled book of backyard projects that's perfect for gifting. Shooting far, flying high, and delivering way more exciting results than expected are the goals of the gadgets in Rubber Band Engineer: All-Ballistic Pocket Edition. Discover unexpected ways to turn common materials into crafty contraptions that range from surprisingly simple to curiously complex. Through vivid color photos, you'll be guided to create slingshot rockets, unique catapults, improvised darts, and a clever crossbow. Whether you build one or all 10 of these designs, you'll feel like an ingenious engineer when you're through. Best of all, you don't need to be an experienced tinkerer to make any of the projects! All you need are household tools and materials, such as paper clips, pencils, paint stirrers, and ice pop sticks.
Oh, and rubber bands. Lots of rubber bands.
Grab your glue gun, pull out your pliers, track down your tape, and get started on the challenging, fun, and rewarding journey toward becoming a rubber band engineer.
About the Author
Lance Akiyama is the author of four books in Rockport's Engineer series: Rubber Band Engineer; Duct Tape Engineer; Launchers, Lobbers, and Rockets Engineer; and The Zoom, Fly, Bolt, Blast STEAM Handbook. Lance is the Science Curriculum Manager for Galileo Learning (STEAM camps for Pre-K to 8th grade), for which he designs STEAM-based lessons and projects for K–8 students. He has been developing hands-on engineering projects for kids since 2011 and working in education since 2006. He lives in the San Francisco Bay area.
Read an Excerpt
> MANY-THING SHOOTER
> PVC SLINGSHOT RIFLE
> BOW AND ARROW
> IMPROVISED DARTS
> RUBBER BAND ROCKET
The Many-Thing Shooter earns its name from its versatility: It can be built from many things. It can also launch many things, including candy, beads, and pieces of cork, to name a few. Every material in the shooter can be replaced with another household item, making this one of the most imaginative, adaptable, and quick-to-build projects in this book. Experiment with different projectiles and rubber-band combinations until your Many-Thing Shooter becomes your go-to DIY sidearm.
TOOLS + MATERIALS
SMALL BINDER CLIP
BOTTLE CORK (OR PROJECTILE OF YOUR CHOICE)
CUTTING TOOL (OPTIONAL)
01 > Make the trigger. Cut a 6" (15 cm) piece of duct tape and split it lengthwise. Use the two pieces of tape to attach the clothespin to one end of the paint stirrer, making sure the pinching tip of the clothespin faces the middle of the stick.
02 > Use the binder clip to clamp the rubber band to the other end of the stick. Fold the binder clip handles down. Using a binder clip allows you to quickly swap out rubber bands with different shooting power or replace broken ones.
03 > Choose your projectile. For indoor shooting, try disks made by cutting a synthetic cork into quarter slices approximately 1/4" to 1/2" (6 mm to 1.3 cm) thick. These corks are dense enough to shoot a good distance and maintain a fairly accurate trajectory but not so dense that you'll break a window. Ideally, the projectile should be slightly wider than the trigger so the rubber band can hold it in place.
04 > You're ready to shoot! Squeeze the trigger open with one hand. Use two fingers from your other hand to stretch the rubber band into the open trigger. The rubber band should remain stretched taut when you clamp the trigger onto it.
05 > Wedge the projectile between the two sides of the rubber band directly in front of the trigger. This will prevent the projectile from falling out as you prepare your shot and ensures that the projectile receives the full force of the rubber band's elastic energy.
06 > Scan your surroundings for something fun to shoot at. Things that fall over, make noise, or shatter (so long as they're not of value to anyone!) are great choices. Avoid shooting point blank at hard surfaces — your projectile might ricochet back at you.
PVC SLINGSHOT RIFLE
This high-powered slingshot is incredibly accurate and reliable, yet it's very simple to build and to modify. Unlike typical slingshots, this one comes with a satisfying triggered release, allowing you to effortlessly line up your shot before letting loose. This is what rubber bands were made for!
TOOLS + MATERIALS
PVC PIPE CUTTER OR HACKSAW
42" (1 M 6.5 CM) OF 1/2" (1.3 CM) SCHEDULE 40 PVC PIPE
TWO 1/2" (1.3 CM) PVC ELBOW CONNECTORS
TWO 1/2" (1.3 CM) PVC TEE CONNECTORS
TWO 1/2" (1.3 CM) PVC END CAPS (OPTIONAL)
BLACK SPRAY PAINT (OPTIONAL)
4 CABLE TIES
TWO 7" (18 CM) RUBBER BANDS
LARGE BINDER CLIP
2 LARGE CRAFT STICKS
01 > With the pipe cutter, cut three 2" (5 cm) lengths and three 4" (10 cm) lengths from the 42" (1 m 6.5 cm) PVC pipe. Set aside one 4" (10 cm) piece for the slingshot's grip and the remaining 24" (61 cm) length of pipe for the handle.
02 > Choose a well-ventilated area in which to work and protect your work surface from the primer and cement before starting. Apply primer and then cement to both ends of each piece of pipe and inside the openings of the connectors. Assemble the other short pieces of pipe, the connectors, and the end caps by simultaneously pushing and twisting the components together.
03 > Insert the 4" (10 cm) pieces of pipe into one end of each elbow connector. Use a 2" (5 cm) piece of pipe to connect each of the elbows to a tee connector. Use the remaining 2" (5 cm) piece of pipe to join the two tee connectors, turning them perpendicularly to each other. Optional: Top off the two 4" (10 cm) pieces of pipe with the end caps.
04 > Your slingshot will look like this. Allow the cement to set according to the manufacturer's directions.
05 > Affix the remaining 4" (10 cm) piece of pipe to the base of the slingshot as a grip. Attach the 24" (61 cm) piece of pipe to the tee connector for the handle. These two pieces of pipe don't require cementing.
06 > Strap both ends of the rubber bands to the slingshot wye with cable ties. The cable ties should be spaced at least 3" (7.5 cm) apart. This configuration prevents the rubber bands from twisting upon release.
07 > Cut a 2" × 3" (5 × 7.5 cm) rectangle from the cardboard tube. This will form the slingshot's "sling." If you're using plain cardboard, roll it so it curves. You could also fashion a sling from just duct tape, but the tube offers a helpful premade curved shape.
08 > Position the rubber bands around the curve of the sling. Secure the sling to the rubber bands with duct tape, and then test it by pulling it back. There should be even tension in each of the four rubber-band strands.
09 > Make the trigger. Attach the large binder clip to the end of the slingshot handle with duct tape. Press the binder clip open. Further secure the trigger by wrapping tape around the slingshot handle and the inside of the binder clip.
10 > Stack the two craft sticks and bind them together with duct tape. Attach the sticks to the trigger's upper binder-clip handle with tape. This will give you more leverage, allowing you to release the trigger easily.
11 > Test fire! Load your projectile into the sling. Small, round, evenly weighted objects like corks and hard candy work best.
12 > Pull back on the loaded sling. Open the trigger and insert the sling. The slingshot is loaded.
13 > Fire away! Release the sling by grasping the trigger handle.
This project requires some determination to complete, but the payoff is worth it. The crossbow makes a satisfying snap when the trigger is pulled, and it can launch bolts more than 100 feet (30 m)! You can power this crossbow with a piece of string or with a rubber band.
TOOLS + MATERIALS
6 PAINT STIRRERS, 12" (30.5 CM) LONG
PENCIL WITH AN ERASER
DRILL WITH 1/8" (3 MM) BIT AND 3/8" (1 CM) BIT
HOT GLUE GUN
TWO 1/8" (3 MM)-THICK BAMBOO SKEWERS, 12" (30.5 CM) LONG (WIDTHS CAN VARY SO CHOOSE THE THICKEST SKEWERS.)
PIECE OF STRING, 18" (45.5 CM) LONG
SPRING-TYPE WOODEN CLOTHESPIN
LARGE PLASTIC DRINKING STRAW
01 > Begin by preparing the paint stirrers as shown here. For the first, drill a 1/8" (3 mm) hole near each end of the stick. For the second and third, drill a 1/8" (3 mm) hole that is 5 1/4" (13.5 cm) from one end of each stick.
02 > For the fourth paint stirrer, using the 3/8" (1 cm) bit, drill a hole 43/4" (12 cm) from one end. Lift the drill, move it toward the center of the stick, and drill a second hole 1/2" (1.3 cm) from the first.
03 > Using the utility knife, carve out the section between the two holes created in step 2. Carefully cut along the grain of the wood by slowly pushing the knife away from your body and hands.
04 > For the fifth paint stirrer, use the utility knife to score and break the stirrer into two 4 3/4" (12 cm) pieces and one 2" (5 cm) piece. Scoring the wood with the blade as described in step 3, split the 2" (5 cm) piece in half lengthwise. Trim 1/4" (6 mm) off one of the 2" (5 cm) pieces and drill a 1/8" (3 mm) hole near the end of it.
05 > Cut the sixth paint stirrer in half, crosswise. You'll only need one of the halves.
06 > Begin assembling the shaft of the crossbow like a box. Line up the paint stirrer from step 3 with one of the stirrers from step 1 with a hole 51/4" (13.5 cm) from the end. Take careful note of the orientation of the holes in the photo.
07 > Use hot glue to attach the edges of the paint stirrers at right angles. If the glue dries too quickly when you run a thin line of it along the edge, use several beads of glue instead.
08 > Glue the second stirrer with a hole 5 1/4" (13.5 cm) from the end opposite the first. Make sure that the two 1/8" (3 cm) holes line up.
09 > Turn the box over and glue the two 4 3/4" (12 cm) stirrer pieces to the underside of the shaft. The 2" (5 cm) gap in the center will be where the trigger goes.
10 > Make a trigger with the two small pieces of wood from step 4. Position the piece with the 1/8" (3 mm) hole at a right angle to the other, 1/2" (1.3 cm) down from the top. Hot glue the two pieces together.
11 > Set the trigger into place. Choose the thickest skewer and thread it through the holes in the crossbow shaft and trigger. This design relies on the friction between the skewer and the 1/8" (3 mm) holes to hold it in place. The 1/2" (1.3 cm) of the trigger's crosspiece should poke through the cut-out slot.
12 > This is how the trigger should look, and it should swing up and down. If it doesn't quite fit, then you may need to drill or carve out a larger hole or drill new holes for the trigger hinge. When you have it working, trim off the extra lengths of skewer and save the scraps.
13 > Create the guides for the bolt. Cut the skewer scrap and the second skewer to 6 3/4" (17 cm) lengths. Glue the two skewer pieces parallel to each other with about 3/8" (1 cm) between them. The ends of the skewers should line up with the front of the crossbow shaft and the middle of the trigger head. Make sure the ends of the skewer nearest the trigger have a clean and flat cut, or the string might not latch on correctly.
14 > Center and glue the paint stirrer with the 1/8" (3 mm) holes drilled at each end to the front end of the crossbow shaft.
15 > Thread the string through the 1/8" (3 mm) holes and knot the ends. To make the knot tying easier, an 18" (45.5 cm) length of string is recommended, but ultimately the string should be 12" (30.5 cm) long from one hole to the other. The bow should start to bend as you pull the string back a few inches.
16 > Give the string a test by pulling it back and slipping it over the ends of the skewers. (If this is difficult to do with your fingers, use the pencil's eraser to push the string into place.)
You may need to calibrate the tension of the string to achieve the most force. The string should be a little loose when under no tension, but very taut when loaded. If you are unable to load the string at all, then it needs to be a little longer. Trim the ends of the string with scissors when complete.
Note: If the string is slipping off of the skewers, use a utility knife to cut each skewer end, either flat or slightly indented.
17 > Glue the clothespin directly behind the cut-out slot.
18 > Glue the half piece of paint stirrer from step 5 onto the top of the clothespin. The lower end of the stirrer should be between 1/4" and 3/8" (6 mm and 1 cm) from the top of the shaft. This will be used to hold bolts in place.
19 > Test the trigger. Hot glue the cork approximately 1 1/2" (4 cm) behind the trigger. Pulling on the trigger should push the string off the ends of the skewers. If the string gets caught on one skewer, double-check to make sure that the trigger is centered exactly between the skewers. Also check to make sure that the ends of the skewers are about the same diameter and flat.
Create Crossbow Bolts
Now it's time to create the crossbow bolts. There are many options for creating ammunition: pens, pencils, dowels, and even hard candy will work. These bolts, made from drinking straws, are designed for distance.
20 > Cut a thick drinking straw to 6" (15 cm) in length. Insert something dense in the tip, like a 2" (5 cm) piece of a hot glue stick. This piece of glue is called a leading weight. (See the notes on leading weights shown here.)
Tape the glue stick in place and wrap tape around the other end of the straw.
21 > Cut a nock into the back of the straw by pinching the tip until it's flat, then cutting off the corners. A nock will ensure that the bolt engages the string and fires consistently.
22 > Get ready to fire! Load the string behind the skewers on the crossbow. Place your bolt directly in front of the trigger hole, but don't cover it. Close the bolt holder on top of the bolt to keep it in place while you prepare your shot. Fire when ready.
BOW AND ARROW
Branches, sticks, string, rubber bands, pens, rulers, and bamboo skewers can all be used to craft a bow and arrow. This design is one way to do it, and it illustrates the important principles. Like all the projects in this book, it's built to be as fun and effective as it looks.
TOOLS + MATERIALS
2 YARDSTICKS (OR METER STICKS)
DOWEL, 24" (61 CM) LONG
PENCIL SHARPENER (OPTIONAL)
SPOOL OF BENDABLE, NON- ALUMINUM WIRE, AT LEAST 18 GAUGE
01 > Stack one yardstick (meter ruler) on top of the other and tightly wrap the ends together with duct tape. If your yardsticks have a hole at one end, make sure that both holes line up. If there is not a hole, carefully drill one with a 1/4" (6 mm) drill bit, or create another notch as shown in step 2 and simply loop the string around it as in step 3.
02 > Cut a 1/4" × 1/2" (6 mm × 1.3 cm) piece off each corner of the yardstick. Use the utility knife to score the yardstick several times and then break the piece off. Because the grain of the wood runs lengthwise along the yardstick, you should have a clean break. Use pliers to snap off the corners if you have trouble breaking the wood.
03 > Cut a 6' 8" (2 m 20.5 cm) length of string. Fold the string in half and attach it to one end of the bow with a hitch knot. If your yardsticks have a hole at one end, thread the folded end of the string through the hole.
04 > String the bow by bending it significantly while holding the loose ends of the string in your hand. Wrap the string around the second end of the bow and knot it.
05 > Cut a 1" (2.5 cm) piece from the dowel. Tape the 1" (2.5 cm) piece of dowel so that it lines up with the very center of the bow. (If you are using yardsticks, this is at the 18" mark [50 cm on a meter ruler]). This will serve as the arrow rest.
06 > Now turn the long piece of dowel into an arrow. Use the utility knife to cut a V-shaped nock at one end of the dowel. The nock will prevent the arrow from slipping off the bow string when you shoot.
07 > Use the utility knife to whittle the other end of the dowel to a point. Alternatively, use a pencil sharpener for a more precise point.
08 > Wrap fine wire around the dowel near the arrow's tip to create a 1" (2.5 cm)-wide band. Adding this leading weight will allow the arrow to fly straight.
09 > Wrap the wire with duct tape to secure it. You're ready to fire!
10 > Nock the arrow onto the string and rest the shaft on the arrow rest. Contrary to the techniques of real archery, you will pinch the nocked dowel and draw it back until only the very tip of the arrow is in front of the bow. Aim safely, and let go! Sheets of cardboard make great targets.
Darts may be the simplest project in this book, but don't be fooled — creating a super-effective dart is more nuanced than you might think. This project isn't a step-by-step plan, but rather a guide to illustrate what factors contribute to — and detract from — a great improvised dart, whether made from a pen, a pencil, or a drinking straw.
TOOLS + MATERIALS
1 PEN, PENCIL, OR STRAW
INSTANT GLUE, SUCH AS SUPER GLUE, OR HOT GLUE
LIGHTWEIGHT CARD STOCK, PLAYING CARD, BUSINESS CARD
FINE WIRE (18 GAUGE OR THICKER WIRE WORKS WELL)
A pen shaft is suitable for dart making because the casing is fairly light and it's easy to install a pushpin in the end.
01 > Disassemble the pen. The only piece you'll need is the casing. The other components will add too much weight to the dart.
02 > Glue the pushpin inside the pen casing. If the pen casing is irregularly shaped, insert the pushpin into the heavier end.
03 > Cut 2 or 3 small triangular fins from the card stock and tape them to the back end of the dart. Tape each fin on both sides to make sure it stands perpendicular to the dart shaft. Fins are necessary to stabilize the dart. The straighter the fins, the straighter the dart will fly. Use materials that are light yet rigid. If you use card stock or cardboard that is too heavy, it will pull the dart off balance. It is best to have most of the weight toward the front.
04 > Wrap several rounds of wire around the front of the dart. This creates a leading weight, which will help keep the dart pointed forward. (See here for more information about this crucial factor.) If wire is not available, fill the tip of the pen casing with hot glue.(Continues…)
Excerpted from "Rubber Band Engineer"
Copyright © 2019 Lance Akiyama.
Excerpted by permission of The Quarto Group.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.
Table of Contents
PVC SLINGSHOT RIFLE,
BOW AND ARROW,
RUBBER BAND ROCKET,
MINI SIEGE ENGINES,
ENHANCED MOUSETRAP CATAPULT,
FLOATING ARM TREBUCHET,
DA VINCI CATAPULT,
About the Author,