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 | Ancient Advice:
Take Pictures of your machine. |
Despite having a nifty engineering section on this web site, I still get lots of
email asking for advice. This is a repository of all interesting bits of
wisdom our team has gleaned over the years that doesn't fit anywhere else.
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Traction Trebuchet Advice
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 | | Juggernaut flinging with the History Channel |
- Your counterweight needs training. They know it's dangerous, and it makes them feel better.
- Devise and use a `keeper line' for your sling. This keeps your counterweight from being whacked in the head.
- Make sure draw-lines are affixed to the arm securely. If they fall off, the arm will konk someone on the head.
- Advise your counterweight to not bend their arms. Use gravity instead. (It's more efficient and stronger.)
- Make sure everyone on the counter weight team knows how to count to three.
 | | Juggernaut 2 |
- Counterweight should be created in manageable chunks. 400lb blocks seem cool, but are instead lame.
- Never stand under the counterweight.
- Never put body parts where the throwing arm wants to go.
- Take advantage of all mechanical advantage available to modern hobbyists.
- If nothing breaks, you don't have enough counterweight.
 | | Roger and the Stubborn Trigger |
This advise is for any torsion machine with three inches or more of rope.
- Never use a wooden Epizygis.
- Never use a mild steel bolt for an epizygis.
- Never use a wooden modiolus.
- Your first machine should use the cheapest rope you can get. It will be trashed.
- Consider buying a trigger. Crafting your own results in many repairs.
- Never Ever put a body part in someplace the arm may like to be some day.
- Bring a spare spanner (torsion tightening beam)
- Bring a spare throwing pouch.
 | | Human Powered Centripital |
Centripetal machines are surprisingly complex.
- Make your throwing pouch as simple as possible.
- Balance your machine well, but make sure it works ok unbalanced.
- Place your trigger or actuator as close to the axle as possible. This reduces the shock load.
- Tune your machine with many practice shots before any competition throw.
- Do not expect any mechanical gizmo to work as expected when spinning at high speed.
 | | Torsion and Youth Lineup, 2003 |
Once you have built a large machine, it must go to a competition!
- Your catapult design must account for double-duty. Chunkin and fast assembly at a remote site.
- Follow the rules! There aren't that many. It would be embarrassing to forget one.
- Keep it clean when TV cameras are around. You may never live it down.
- Don't use "compressed air helium". Dat is 'gainst the rules.
- Don't expect to win your first year out. Assume failure and have fun mocking those who missed this advice.
- Study as many other machines as you can while you are there. Before they break is usually best.
- Keep your prize punkins in a "Punkin' Safe"
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