Introduction: PVC Trebuchet

This is a trebuchet designed for a 40ish pound counterweight and launches a golf ball, baseball, or similar sized object. It may be used to siege a PVC castle.


3/4 inch PVC:

6' 9" - 4

5' - 4

4' 4 1/2" - 2

6" - 6

7" - 4

2" - 6

1 inch PVC:

2 1/2" - 8

1" - 26

3" - 6


7' - 2

6' - 1

4' - 1

5' - 1

10' - 1

screws - at least 14

1" Fittings:

45º elbow - 8

90º elbow - 3

3-way corners - 4

4-way xyz edge tees - 4

3/4" fittings:

45º elbows - 4

90º elbows - 2

tees - 6

2" end cap - 1

Wood board 3" x 6' - 2

Step 1: Cut the Notches for the Wideners

The 1" pieces of the 1" PVC are used to widen the ends of the 3/4" PVC to allow compatibility with the 1" PVC fittings. For this to happen, notches must be cut at the ends of the affected 3/4" sections. The notches should be made about half an inch into the PVC.

2 Notches must be made on:

ONE end of BOTH 4' 4 1/2" sections

BOTH ends of ALL FOUR of the 7' sections

ONE end of ALL FOUR 7" sections

ONE end of FOUR of the 6" sections

BOTH ends of ALL FOUR 5' sections

Step 2: Add the Wideners

The 1" sections of 1" PVC are the wideners. They must be forced (it is not easy) onto the ends of the notched PVC pipes. Once they are started, you can force them on the rest of the way with a hammer or, if the it is long enough, by throwing the piece straight at the ground.

Step 3: Build 2 of the Middle Sections

Attach 2 of the 7" sections with wideners to the two 3/4" tees. Connect the tees with a 1 1/2" piece of 3/4" PVC. Build 2 of these.

Step 4: Construct the Base

Connect two 5' Sections each to a 1" connector. on each of the ends, add a 3-way elbow. Insert a 2" piece of 1" PVC into the vertical outlet of each 3-way elbow and add a 45º elbow to the ends of the 2" pieces. Connect a middle section assembled in the previous step to the front 3-way elbows and the middle 4-way tees.

Step 5: Assemble the Arm Supports

Attach one of the 6" sections with a cap to the edge of a 1" 4-way tee. Connect a 3/4" tee to the bottom of the 6" piece. Attach 2 45º elbows to the sides of the 1" 4-way tee with two 2" pieces of 1" PVC.

Step 6: Assemble the Arm Supports (2)

Attach a 6" piece of PVC with widener to a 90º elbow. Drill holes in the elbows for the trebuchet arm. Attach a 1 1/2" piece of PVC to the elbow and connect a 45º elbow to that. Attach a 6" piece of PVC to the 45º elbow and add another 45º elbow to that. Add a 1 1/2" piece of PVC to that.

Step 7: Assemble the Arm Supports (3)

Join the sections created in steps 5 and 6 together

Step 8: Add the Diagonal Supports

Connect the 6' 9" sections to the 45º elbows on the base.

Step 9: Add the Vertical Supports

Connect the 4' 4 1/2" to the 2 center 4-way tees. Add the arm supports to each side.

Step 10: Prepare the Arm

Drill a 3/8 inch hole 2 feet from the end of the arm. Henceforth, it will be assumed that the holes are parallel with the ground it is now known as the x-axis and the other axis will be referenced accordingly. Put the cap on the short end of the arm and drill a hole 1" from the end on the x-axis through the cap. holes must be drilled, but not all the way through, at 2" and 3" from the long end. A hole must be drilled all the way through at 8". Holes must be drilled part way through along the y-axis (from the bottom) at 1/2", 2", and 23". Holes must be drilled at 2" and 3" on the top of the arm.

Tie a figure eight knot on the end of a 6' long rope. the rope must bu run as follows:

1. Run it through the inside of the arm and out of the first tophole.

2.Run it back through the second top hole

3. Run it down throug the second bottom hole it up through the third bottom hole.

5. fish it back through to the end end out the second side hole

run it back through the first side hole and out of the pipe

Step 11: Make the Trough

If your wood is of adequate thickness, you can glue or screw them together. Otherwise, you can tape them together and screw them to a 1" elbow with 3" sticking out on either end. there should be at least three of these braces at the front, middle, and back. Place the trough onto the vertical pointing tees on the base and screw the elbows to the tees.

Step 12: Attach the Arm

Remove the elbows on the arm supports and put the bolt through them and the arm and reattach them to the structure.

Step 13: Make the Sling

Make a duct tap swatch and cut it a quarter way through at the middle. Add a place to attach the ropes at the ends. Tie the ropes to the sling with a bowline. Attach one end of the rope to the first hole on the bottom of the trebuchet arm and tie a figure eight knot. Tie a bowline to the end of the second knot.

Step 14: And... Yeah

Thats it! You're done! You can now launch things into the air or siege some building somewhere. The world is now yours to take over.