Kickstarter Trebuchet Kit

So you’ve received your Kickstarter Trebuchet Kit, and you’re itching to assemble it. First of all, thank you for being a supporter of The Gizmo Dojo! We can’t do this without you!
To assemble this kit, you’l need a few things, and it’ll take a few hours.

ToolsTools Needed:

  • Wood Glue
  • Scissors
  • Clamps (holding items with patience can work, but it’ll take longer)
  • An X-acto knife, awl, or some other tool to puncture fabric
  • A cutting mat is a nice work surface, and parchment paper helps keep things from sticking to it.


In addition to the tools, you’ll need a good work surface, and some time. You’ll be gluing and clamping parts, and then waiting for them to set before you can continue. In some cases, the order in which you assemble parts is critically important, so if you like to go off-book, make sure you at least read through and understand the instructions, so you won’t glue yourself into a corner!


When you pull your kit out of its protective cardboard sandwich, it will likely fall apart, so I recommend that you open it over your work surface. It should look roughly like this:



Step 1: Assemble the Spacers

First, locate the four circular spacers in your kit. They’re originally located in the outer side pieces. Here’s what they look like:


Glue them together in pairs, face to face. Due the the nature of laser cut parts, you’ll notice that one side has more surface than the other. This is because a laser cuts from the top down, exposing the top to heat longer than the bottom, and creating a wider kerf at the top. In other words, the sides are not perfectly vertical, so one side will always be slightly larger than the other. In this picture, the one on the left is the smaller side (top), and the one on the right is the larger side (bottom).


I recommend gluing the larger sides together, those like the spacer on the right. This will give a little more room to work. Start by adding a small amount of glue around the face of the spacer. Try to keep it light, so that you don’t get much oozing when you clap the parts together. When you stick them together, twist them a little bit to spread the glue. Align them as accurately as you can; better alignment means less friction for your trebuchet! Make sure that you wipe all of the excess glue off of the inside and outside of the spacers once they’re clamped (if you can – wipe the inside thoroughly while you have access to it). Set these aside to cure. You should have two sets of glued spacers like this:




2. Assemble Half of the Basket

Now, gather the parts of the basket:


Place one of the large, logo-festooned side pieces face-down on your work surface. Add glue to one edge of the bottom piece and place it along the bottom of the side piece. Now, the next bit is tricky. In a fit of Murphy’s Law forgetfulness, the end pieces were designed almost, but not quite, symmetrical, top to bottom. Test fit them in their slots, and then glue them in when they fit properly:


Now, place the other side piece on the assembly without glue, to maintain alignment (you’ll glue that piece on in a later step – don’t do it yet!). I’ve placed a wrench on it to add a little weight. Set this aside to to cure.



Step 3: Assemble Firing Arm

Grab the firing arm, and glue the spacers from step 1 onto the sides of it. Careful gluing and alignment are important in this step. Again, better alignment means less friction.

Take one glued pair of spacers, and glue it to one side of the larger circular hole in the firing arm. Use the same twisting technique to spread the glue, then clean and clamp the parts so they can dry. The full assembly should look like this:



Step 4: Start Assembling Base Structure

Now it’ll really start to take shape! Gather the components for the base structure:


Apply glue to one edge of the bottom panel, and slide it into the slots in the bottom of one side piece. Two of the tabs will stick out farther than the side piece. These are for the decorative wheels. Take care to clamp this as square as you can, and set it aside to cure.



Step 5: Assemble Axles

Now retrieve the firing arm assembly, and collect the axle parts:


Place one half of each axle through the firing arm, as shown:


Carefully put glue on the other halves of the axles, and slide them through the firing arm to complete the axles:



Once these dry a bit, slide the shorter axle towards one side, and put quite a bit of glue where the center point of the axle is.


Slide that back so it’s centered, and set it aside to dry.

After these first 5 steps are complete, and everything’s dry, your kit should look like this:



Step 6: Complete the Basket

Now you’ll need the firing arm and the basket assembly, along with the remaining basket side piece. Align the shorter of the two axles in the hole in the assembled basket. Make sure that the firing notch at the other end of the firing arm is facing upwards:


Now, apply glue to the edges of the basket pieces or to the back of the remaining basket side. Slide the basket side into place, making sure that the short axle turns freely in the hole in the top of the basket side:


Weigh the basket side down, or clamp it. I placed three of the wheels underneath the basket, and propped up the end of the firing arm with the other wheel:


Let this dry before you move on to the next step. This would be a good time to glue together the ammunition. Glue and assemble the 4 projectiles to make these:


Handily, we’ve included some of the round off-cuts in the kit, which can be used as backup ammunition, if needed.

Step 7: Complete the Frame

Once the arm assembly has dried from step 6, gather it and the partially assembled frame. Place glue around the inside of the plus-shaped hole in the assembled portion of the frame, and insert one end of the longer firing arm axle:


Carefully apply glue to the remaining side edge of the base, and to the inside of the plus-shaped hole in the remaining frame side, and slide the frame side into position to complete the frame of the trebuchet:


Once again, clamp it or add weight to secure the frame as it dries (pay no attention to the giant, laser cut gears in the background):




Step 8: Adding the Decorative Wheels

Now that the frame’s complete, you’ll add the decorative wheels. They don’t add a lot to the functionality, but they do improve the appearance of the trebuchet, and add a modicum of improved performance, as the wheels can slide on a surface more easily than the bottom of the frame can.

Add glue to one side of each wheel, carefully aligned so as to not extend past the part of the frame it will sit against, and glue the wheels in place. You can glue all of them at the same time, and use clamps to secure them in place while the glue dries.


That’s it for the bulk of the trebuchet! The only thing left is the sling assembly.


Step 9: Cut and String the Sling

You’re almost finished with your trebuchet! Fold the string that came in your kit in half, and cut it at the half-way point. Try to keep it a little slack when you cut it, so that the cut is a little more accurate.


Now, cut a little off one side and one end of the fabric rectangle to make your sling. You’ll want it a little bit bigger than 1″ x 2″, so around 1.25″ x 2.25″ or so works. You can leave it the original size, if you like, and trim it later if you feel like it’s too big, too.


Now comes the tricky part. You’ll need to cut four holes, pretty evenly spaced, along the short ends of the sling. Don’t get too close to the edge, or the fabric might fray. Stay about 1/8″ away from the edges (mine are a little close to the edges in the picture – I later had to repair the frayed bit with a couple drops of glue).


Thread the string through the holes on each end, one string on each end. Make sure that the to ends show the strings on the same side of the cloth.


You’re very nearly there, now! Take one of the two strings, and thread it through the small hole in the firing arm. Tie the string into a loop, using a single overhand knot, as you’ll need to be able to adjust the length of the loop.


Tie the other string into a loop of about the same size as the first one, using the same technique so you can adjust it later.


Locate about 3oz. of small weights, such as some spare change, nuts, or washers. Place them in the basket.

Now, you’ll need to test fire, and adjust the length of the string loops to make sure that it’s firing at about a 45 degree angle above horizontal. Place a projectile in the sling, and loop the loose string into the firing notch in the firing arm. Using one hand to hold the frame of the trebuchet, pull the sling back along the base plate of the trebuchet with your other hand until the arm makes contact with the base. Release the sling to fire!

The sling should swing all the way over the trebuchet, and fire towards the basket. If the strings are too short, it will likely release early, and shoot before the swing is complete, or straight up. If they’re too long, it will likely release too late or not at all, and shoot too low. Adjust the lengths of the strings until you’re happy with the firing trajectory. Altering the amount of weight in the basket will increase or decrease the power, and therefore the range, of the shot.

Your trebuchet is complete!


Posted in Instructions, Kits.