Introduction: Quick-n-Dirty Trebuchet

Picture of Quick-n-Dirty Trebuchet
No Tools, No Drilling, No Cutting, No Lumber, No Saw, No Hardware, No Need to wait for your allowance, Super Easy, Super Cheap, Fast Build.

You probably already have everything necessary to build this Trebuchet in your house right now.

It's made out of:
9 Chopsticks*
2 Toothpicks
3/4" or larger masking tape
2 rubberbands
3 paper clips
string
Something for a weight - I used a fishing weight 5.75oz or 166g - it could handle twice that though.

The complete tool list:
Scissors

  • I used the better Bamboo ones you buy - 20 for 3.50 at Amazon. I didn't buy these, I've had them for years. They also make imitations of this style in hard plastic. They would probably work great also. The ones I used are 10.25" or 26cm. They are not fancy, no artwork or lacquer. This was an ideal length. You could probably use the free ones from take away, but they are shorter and lighter. You probably wouldn't be able to do quite as much weight, or fling as far. You could probably use lacquer ones also but they are expensive and it would be harder to keep it together as the tape wouldn't stick to the lacquer as easily. They are often shorter also. You could also try it with pencils but once again, they are shorter so you wouldn't get the performance that you get out of these chopsticks.

This video shows you what the finished trebuchet looks like.

This video lets you see it fly.

Step 1: Parts

Picture of Parts

These are the parts I used:

9 Bamboo chop sticks
3 paper clips
2 rubber bands
3/4" masking tape - wider is fine
2 toothpicks
some string
and a weight

The only tool I used was a pair of scissors. (you could probably use a pocket knife instead)

I don't have any plans or measurements except the chopsticks are 10.75" or 26mm. The weight I'm using in the video is 5.75 oz or 166g. It's a fishing weight. I tried a heavier weight but it goes 20' and hits the wall. My longest space in my apartment is 20', so I can't check right now how far it would go.

I also didn't try to tune it or see how much weight it could handle, so It might be capable of more.

Step 2: Assembly

Picture of Assembly

Everything is just taped together with masking tape. I didn't try to make pretty attachments. You could probably make them look a lot nicer and cleaner. It would probably look really nice just tied together with string, like they used to use leather on the originals.

I started with connecting the top part of the A Frame sides. I keep calling them the 'saddles' in my head. They hold the top of the A frame together and support the boom axle (paper clip). When I was finished with the whole thing, I realized those were just slightly off and it was making the boom pull down crooked, so I re-taped them.

I'm going to skip this step now and do it at the end. When I did at the end it was a lot easier to get it accurate so even though you see them in place during the other steps don't worry about it, we will do them at the end.

So you should start with the base of the A-Frames. It's two vertical chopsticks taped to 1 horizontal chopstick. The vertical chopsticks are about 1 3/4 inches from the end of the horizontal. Be aware that the tops of those vertical pieces form an A frame and eventually will almost meet, so when you tape the bottoms, make sure you install them in a way that they will easily come together at the top when we tape the top.

I had two different styles of chopsticks to work with. There were some tapered and some that were just round cylinders. They were all the same length though. I used 4 matching tapered ones for the sides of the A frame because it's important that they meet at the same point. The other ones don't really matter and can be any style, just make sure they are the same length.

When taping, get as much adhesive touching the uprights as you can - press the tape into the sides. The chopsticks will slide under the tape if you pull hard so be generous and use long pieces of tape.

I didn't measure, just eyeballed it. After you do one set, just put it next to the first and make them match.

Step 3: Add Base Cross Pieces

Picture of Add Base Cross Pieces

These add stabilization and keep the A-Frame square. Let them sit flat on the ground like the other horizontals so they can provide more stability.

Photos tell how I did it.

They extend about 1 1/2 inches from the end of the A-Frame Horizontals.

Step 4: Boom Axle

Picture of Boom Axle

I made the boom axle out of a normal paper clip - not a large one.

The top one was my original. The bottom one is the new one.

I realized during the rebuilding that making the bent loop in the center - longer - works better. So where I have the corners are a little too close together. Move those corners out another 1/4" on each side.

When you get it into the shape pictured, curve the bottom wire up until the side hooks lay flat, like the original one. The curve is more like the radius of a tube of lip balm not the chopstick.

(in the second photo, I want your curve to be larger, make it clear the chopstick by 1/4")

This is the boom and axle. I attach these together with a rubber band. You want the rubber band to wrap on the side without the wire - back and forth. The rubber band should pull on the sides of the vertical curve - not the sides of the hooks.

Don't make the rubber band really tight. Just snug. If it's too tight it will deform the hooks and if it's just snug, you will actually get a little assist from the rubber band, when you launch.

Step 5: Weight Hook

Picture of Weight Hook

This is the weight hook. It's just a paper clip wrapped around the end of the boom. The side of the boom with the rubber band is up and the side with the metal is down. (the pretty wrap job went away when I increased the size of my curve - but this is what is there now and it works fine). Make the weight hook rest on the top of the boom.

To attach the weight hook to the boom use another rubber band. Just wrap it over the parts that are touching the chopstick. Make this rubber band tight.

Step 6: Throwing Hook

Picture of Throwing Hook

This is another paper clip. You can see how I bent it. When you are finished you may need to bend this a little tighter or looser to get the optimal release time, so give yourself room for those adjustments.

Make sure the end that is bent back won't snag your string and prevent release. You see I have mine tucked under the bottom corner of the hook and not off to the side. The string can slide freely up the hook and not get caught on the end of the wire.

You could actually bend it with the end being at the top of the hook instead of looped back over. It's a little safer with the end looped. If you accidentally release it, and this hook hits you, it won't cause any damage like a pointed hook would.

I could have bent the hook flatter. I had a little sideways bend there but I was trying to do this entirely without tools. A pair pliers, or even a tap with a hammer would straighten that out.

Once again, it's not important for function. It works fine like this.

The flat part that goes on the boom lays across the top side of the chopstick and is attached with tape (you could use a rubber band also - but tape isn't as heavy and you want the smallest weight possible on this end of the boom).

Step 7: Taping the Saddles

Picture of Taping the Saddles

This is the top of the A Frame. The chopsticks weren't meeting with the first tape job so I redid it.

The chopsticks do not touch. Allow the width of one or two chopsticks between the points of the A's. Also allow a tiny bit of the chopstick to stick out above the tape. Add a few extra layers of tape on the saddles, this is where the boom axle will rest.

Step 8: Toothpick Brace

Picture of Toothpick Brace

This X brace goes between the tops of the A's. It's kind of hard to get in. Just keep trying. The tape will slide a little bit (well this blue tape will) so you can adjust the X brace until the tops of the A's are even on both sides. The saddles at the tops of the A's should be about 3/4" apart.

The X brace also stops the boom from swinging past vertical. If they don't stop the boom and it continues on over, the load will be thrown down to the ground right in front of the trebuchet. If you stop the boom at vertical, the load gets flung straight out.

The second image is a toothpick wrapped in tape. I've sliced the center so the two toothpicks can rest right next to each other. You don't have to do it this way. You will probably cover this whole area with lots of tape anyway. I've left the ends of the tape past the toothpick ends open as these will wrap around the sides of the A Frame.

The pictures show it sitting flat on the surface but you will be taping it with the sides already erected. This lets you position the brace in the ideal position to hold the tops of the A's and the saddle the ideal distance apart. (the tape at the top of the A's in the flat pictures was the tape that was removed and redone).

Keep adjusting the X -brace until the tops hit just right - 3/4" apart with both sides matching. When you get it spaced just right, wrap several pieces of tape around the center of the X going both directions to lock it in place.

(the saddles in these photos were all redone. They need to meet at the same place and the tip of the chopstick should stick out above the tape).

Step 9: Fitting the Boom

Picture of Fitting the Boom

Here you can see that I actually pull the ends of the boom axle hooks out some, so the tops rest on the tops of the saddles. The ends also have to be pulled out. When the boom is armed, you don't want the ends of the hooks hitting the chopsticks of the A frame. You might just have to fiddle with this until you get a bend that doesn't hook the structure.

You can see how the boom is stopped by the X-Brace (Your weight hook will already be in place).

So you are done!

Fiddle with the axle bends so that the boom doesn't hit the sides of the a frame. You might have to bend the hook tops forward or backward also to get a good swing - that why I told you to keep the rubber band on the curve of the axle and not the sides of the hooks.

What you see me flinging in the videos are pen caps. I took a string and tied loops at both ends. Then hooked the pen cap over the middle of the string. Both knotted loops are put onto the boom hook.

Pull the projectile between the legs and hold it under the weight. Then release. You may need to adjust the angle of your loop hook to get the release timed just right.

That's it.

Have fun!

Comments

ShengZ (author)2016-02-15

How do u tie the rubber band and the the paper clip together?

ShengZ (author)2016-02-15

Can I use regular tape? What if I don't have paper clip can it still work?

yapoyo (author)2012-09-07

would bamboo skewers work?

nfathin (author)2011-08-06

hey , really a saver for my sci project , but i dun get y my trebuchet cannot shot ? the sling is a necessary? and short or long sling is better? thks

Peter_Feliest (author)2009-01-10

youThat's a COOL trebuchet.. I actually just had to build one the very next day that I saw this... I'm adding some pictures to show you mine, and as you can see I made some adjustments to your instructions (like using a cotton-string, and I used some tools like glue and a knife...)

Nice, good for a school project! lots-o-fun

SFHandyman (author)Peter_Feliest2009-01-10

You made one! Yay. I love that. It looks great. My tape let go after a few months. The string is an improvement. You made a lot of improvements. The X-brace on the front looks especially nice.

riceman595 (author)SFHandyman2011-06-03

ur instructions ar great :)

Peter_Feliest (author)SFHandyman2009-01-12

Actually this treb is an ongoing project... Still trying to make it that much better or authentic looking.

I've added a release mechanism and a proper sling and a net. See pictures for details. In the net picture, there is projectile inside which is about one cm cube for LOW LOW trajectory and glued 4 of them together for a higher trajectory, my treb has a range of about 2 meters.

riceman595 (author)2011-06-03

the toothpick support did not work well. i added a lower support. pencils work great I built it with me Amego

iApple guy (author)2011-02-03

how far dose it launch?

instructable doggie (author)2010-03-02

if you used pencils inseatd of chop sticks would that work as well

I don't see why not. Give it a try. It will be shorter but should work fine.

Goalie1 (author)2010-02-05

Wow!! That is really cool!

SFHandyman (author)Goalie12010-02-07

Thanks

madvillain (author)2010-02-07

what is the ammunition for this?

SFHandyman (author)madvillain2010-02-07

It is the cap from a pen.

Matt4_16 (author)2009-08-09

This is pretty sweet i just made one except i didn't have toothpicks so i used extra paper clips (1.5 paperclips for a toothpick) and i used duct tape. mine throws up more than over though.

SFHandyman (author)Matt4_162009-08-11

That's great.

jc8952 (author)2009-02-09

My school hosts a regional competition for the National Science Bowl for high school students every year with the winner going on to the national competition in Washington, DC. This year I was in charge of finding some sort of competitive project for the teams to build and compete with during the lunch break. I chose your quick and dirty trebuchet and made a kit for each team. I made a few changes to your plans. I used 12" long 1/4" cut dowels instead of chopsticks since I didn’t have a cheap source of chopsticks. I did not give them rubber bands and instead they were to tape the paperclips on for the axle. They were given a 200 g weight with a loop of string taped to it for the weight. The projectile was a mini binder clip with a loop of string tied to it. The complete kit contained the 9 dowels, a roll of masking tape, 4 paper clips, the 200g weight with loop of string attached, mini binder clip with loop of string attached, your printed instructions as a guide and a sheet explaining the rules of the competition. It worked out quite well. The teams were given a copy of your plans as a guide and 20 minutes to build their device. The competition was they were to launch the projectile three times and it had to land inside a track 4’ wide each time. The distances of the two best of the three throws were added together for their score with a foul (outside the lines) counting as zero distance. We had 12 teams participate and the winner had a score of about 44.5 feet. They all had fun and I think learned something too.

SFHandyman (author)jc89522009-02-11

That is so excellent. 44.5 feet! Wow. This makes me feel so great. That's why I make Instructables. Where is your school? Any video or photos? Thanks again.

jc8952 (author)SFHandyman2009-02-14

Sorry I don't have any photos or video. I should have brought my camera along. I am a physics prof. at the Univ. of Arkansas - Fort Smith. We host a regional competition every year for the U.S. Dept. of Energy's National Science Bowl. ( http://nationalsciencebowl.energy.gov )

Fredward Sr. (author)jc89522009-07-23

Sounds fun id love to compete in sotn like tht

SFHandyman (author)jc89522009-02-14

That's cool. I'm just really happy that you could use it and had so much fun. Thanks so much for letting me know.

jc8952 (author)jc89522009-02-09

I forgot to add that I also gave them toothpicks for the cross bracing.

kitkaty (author)2009-04-11

actaully the part where i fit the broom in is difficult for me..so any suggestions?

SFHandyman (author)kitkaty2009-04-13

I cant know what is going wrong without seeing it. Can you post a photo somewhere?

kitkaty (author)SFHandyman2009-04-15

acaully nevermind, I got it to work..sry for bothering you

SFHandyman (author)kitkaty2009-04-25

No bother. Glad it's working.

somoko2 (author)2009-03-09

I have a project due tomorrow and I am building this trebuchet. It is multiplied by 4 and tennis balls do not fly out of the sling. how do I make it work.

SFHandyman (author)somoko22009-03-09
There is no way this treb can throw a tennis ball when increased by only 4x. The max a 4x increase can throw is the weight of two quarters.

A quarter weighed on my little cooking scale weighs 5.7g (2 to 3x as heavy as the 2-3g pen cap). Your tennis ball weighs 58g. 20 to 30x heavier than my pen cap. If you scaled this trebuchet up proportionately it would need to be at least 20x larger to throw a tennis ball.

Try throwing something that weighs less than 2 quarters and use a weight of at least 1.5 lbs.

  • This is not scientific measurements. It's just an approximation to illustrate the problem with your design.

Part of a project like this is doing the calculations. 4x size requires 4x the weight and can only throw 4x the weight that I threw.

Crumple up a single piece of paper and cover it with a little bit of aluminum foil and try to throw that. If it's still too heavy, tear the paper in half and try again.
chadandjody (author)2008-12-26

I've been looking for good instructions on making a trebuchet or catapult. Yours is by far is the best explained and has the best photos. Very nice.

SFHandyman (author)chadandjody2008-12-27

Thanks. I'm glad you like it.

8doug8 (author)2008-11-09

its cool and all but there is a problem, a trebuche is supposed to use a sling firing mechanism and a counter weight. you only got the counter weight, no sling.

SFHandyman (author)8doug82008-11-09

The sling is mounted on the pen caps that I'm flinging. It should stay with the boom in a traditional Trebuchet, but this way you just make a custom sling to fit what you want to throw. So the sling is there. It is the string at the end of the boom that holds the projectile.

8doug8 (author)SFHandyman2008-11-09

ok thats what I meant I didn't notice the pen caps I was short on time and only saw your videos sorry about the confusion if you happened to think of a way to make a sling that stays attached that would be nice

kiss my donkey (author)2008-11-02

good job

Thank you

pieboy1992 (author)2008-03-13

oh.... it's a minature.... i thought it was a full scale model. but still this is pretty kick ass, you guys got the right concept. next step: FULL SCALE MODEL!!! WOOOOO

SFHandyman (author)pieboy19922008-10-28

Thanks.

0987654969 (author)2008-04-28

awesome i built mine out of knex and it gos about 16 ft

SFHandyman (author)09876549692008-10-28

Great!

perth (author)2008-10-27

I can't figure out how to wrap the rubber band around the chopstick and the paper clip. The visuals don't help me much. Help would be appreciated since I want to do his with some students. It is step 4. Thanks for any information that is easy to understand.

SFHandyman (author)perth2008-10-28

To understand better try this: straighten a paper clip out until it is shaped like a "U". Put it around the chopstick, then just wrap a rubber band back and forth over the straight parts sticking out on either side of the chopstick. It will be harder to do, because the straight parts are so long, but it will be less confusing without all the other bends. It doesn't matter how perfect, or pretty or what pattern you use. Just wrap it so it holds onto the stick. The metal loop of the paperclip will be on one side; and the rubber band, wrapped back and forth, will be on the other. The axle is wrapped the same way as the U. It just has curved ends.

bounty1012 (author)2008-03-10

lol

righthandofthedevil (author)2008-02-26

i noticed u said 26mm. did u mean 26cm. because 26mm would be really small

Yep, You got it, I'll fix it. I've been cooking in metric for a while, but just recently tried to always include metric length. I still can't imagine most of them in my head yet. Thanks.

LdBd45 (author)2008-02-23

Great and simple, just what my son ( and his father) needed for the trebuchet project for his gifted class. Thank you!

SFHandyman (author)LdBd452008-02-23

No Thank you. Now, are you ready for all the phone calls from the other Moms complaining about missiles whistling past their heads? Hahaha Have fun with it. I would suggest that you throw something like a ping pong ball. I'm afraid some child might - in an attempt to imitate my pen caps - and throw a whole pen, which could break and scatter ink. I should have thought of that when I was writing it.

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