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- What is "Punkin Chunkin"?
- Chunker styles
- Safety
- Physics
- Get started!
- Q&A
- Big maker nerd
- LEGO Robo-Clippy, Bad AI In A Box, LED Lanyard
- Partner Solution Architect @ Microsoft (ex-Yahoo!, ex-Nortel)
- Trebuchet expert for Dude Perfect (S2.E6)
- Organizer of "SlingFest"
- Competed Punkin Chunkin
- Some people get siege weaponry information from social media
From Wikipedia:
- Catapult - a ballistic device used to launch a projectile a great distance without the aid of gunpowder or other propellants
- Trebuchet - uses a rotating arm with a sling attached to the tip to launch a projectile
- A trebuchet is a type of catapult
- e.g. All squares are rectangles, but not all rectangles are squares
- Accuracy - ability to hit the intended target
- Precision - ability to hit same spot
- Annual event since 1985
- Organized by "World Championship Punkin Chunkin Association (WCPCA)"
- Cancelled and restarted multiple times due to injuries, legal and logistics issues
- 2023 was in Vinita, Oklahoma
- Annual event from 2011 - 2016 in DFW
- Last event had 1000+ attendees
- Local news coverage
- Air cannon
- Centrifugal
- Torsion
- Catapult
- Trebuchet
If you ever built a potato gun or at least had the opportunity to shoot one, Air Cannons at the annual Punkin Chunkin are the big daddy of potato guns. Using compressed air, nothing flamable, these machines shoot pumpkins over 4,000 feet
University of Delaware video example
These machines build up centrifugal force in an circular motion and have ways to release the pumpkin at the optimal trajectory for an outstanding distance shot.
A Torsion machine is any device that uses twisted rope as its primary source of power. It relies on a rope that works by torsion or twisting. The rope stores mechanical energy when it is twisted. The amount of force it releases is proportional to the amount it is twisted.
French for "overturn".
Earliest ones seen in China ~4th century BC (powered by men on ropes: traction trebuchet). Counterweight replaced people ~12th century.
Modern trebuchets are powered by gravity, and use a counterweight attached to an arm to swing the ballistic attached to a sling around and release at an optimal angle.
- Fixed counterweight
- Hinged counterweight
- Floating Arm
- MURLIN
- Human powered
- And many more
- Weight is attached directly to the arm
- Weight drops in an arc
- Weight is atached to a pivot point on the arm
- This enabled a better "drop" of the weight
- Frame on wheels helps ensure more force is delivered to ballistic
Example - Slingfest Example - Slingfest
Credit: LanceMakes @ Instructrables
Example - Slingfest Example - Test shot
A fun, simple, weekend project to toss tennis balls.
Machines can use any kind of stored energy that can be stored by a single person in two minutes.
- Built by Corey Winesburg + his welding students in OK
- Won Punkin Chunkin student division + Adult Trebuchet record holder (3377 feet, 2019)
- Split counterweight
- "Cone of Danger"
- e.g. danger zones of a horse
- Invest in good firing mechanisms
- e.g. snap shackles
- Treat loaded catapult like loaded gun
- Pre-flight checks
- AVOID DRY FIRING (Like a bow and arrow)
- Checks structrual integrity after each launch
Example:
- Safety on
- Ballistic loaded properly
- No twisted or obstructed rope
- Range is clear
- Nothing valuable in "cone of danger"
- Guinness world record: pneumatic cannon at 5,500+ feet
- Pie-ing a pumpkin (i.e. "pumpkin pie in the sky")
- Everything in previous formula
- Release Angle
- Distance of axle to counterweight and sling
- Length of sling
- Materials used
- Rope will stretch
- ...
- Pick a design
- Recommendation: Hinged counterweight (10 lbs)
- Start small
- Recommendation: Baseball (5 oz) or Tennis ball (2 oz)
- Experiment + Learn
- Recommendation: Outside (200 feet)
- Go bigger
- Recommendation: Safety
- Basic woodworking
- Measure, cut, join
- Knots
- Knot 3D app
- Basic math
- Find midpoints, calculate angles
- Project planning
- Kanban board
- Saws (hand, circular, compound miter, table)
- Levels
- Clamps (SO MANY CLAMPS)
- Drills (standard, impact)
- Markers (carpenter pencils)
- Workbench (Simpson strong-tie)
- Marine tools (quick release snap shackle, marine rope)
- Digital angle finder
- Get started with Common boards (e.g. pine) from Home Depot / Lowes
- Don't get treated wood (arsenic)
- Listed in depth and width (e.g. 1x3, 2x4, 1x8, etc.)
- Board is cut THEN planed (to make straight-ish)
- e.g. 2x4 is NOT 2"x4". Actually about 1.5" x 3.5"
- e.g. 1x4 is .75" x 3.5"
- Pilot holes are your friend
Think in terms of a constructing a vessel and label pieces accordingly
- Foreward = where the ballistic is directed towards
- Stern / Aft = backside, opposite of foreward
- Port = When facing forward, on the left
- Starbord = When facing forward, on the right
- Reddit - /r/trebuchet
- Reddit - /r/PunkinChunkers
- Facebook - Texas Trebuchet
- Your local makerspace
- 2024 Pumpkin Chunkin Events and Festivals
- Near Dallas? Nov 2nd in Lewisville! (Contact me)
- How big should I make my arm/sling/counterweight/etc.?
- How many people should I have on my team?
https://lastcoolnameleft.github.io/how-to-punkin-chunkin/
