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Larry Worley's Erector Trebuchet

Hi folks, Doc here. Here's another clever custom model from our live steam guru Larry Worley. Any of you who are "Junkyard Wars" fans like I am will probably have seen one of these machines in action.

Larry writes: "Someone suggested a catapult, so I wanted to try to build a functional one. After checking various designs of sieze machines, I decided on this one. Just imagine; at one time these machines were the 'Heavy Artillery' on the battlefield. Actually this is a 'Trebuchet', meaning it uses a counter-weight and gravity to launch projectiles instead of deriving its power from twisted ropes, tension bars or long balance arms. A true Trebuchet would have a rope sling at the end of the arm instead of a bucket. When the trigger was released the heavy counter-weight would fall causing the arm to move rapidly. The sling pulled the 'shot' down a trough to prevent the ropes from tangling in the machine's framework. This also gave the shot a longer swing and arc before releasing, thus more speed and range.(I tried and tried to use a sling rig attachment on mine, but just couldn't get it to work properly, so I decided on the bucket design).


This model misfires very rarely. It's average range is 9 1/2 feet. I can shorten the winding rope which stops the arm at variable points, thus affecting range. I used a long screw to hold the trigger rope (string), but the threads kept abrading the string rather quickly. I tied a 5 hole strip to it and it works just as well.


The counter-weight bin contains 24 ounces of lead shot. Using any more weight would risk damaging the pieces. I found that a nickel is the right size and weight 'shot' for this model. After Christmas, when the smaller tree ornaments (about 1 1/2 inches diameter) are on sale, I might buy some and sling them against the bricks out on my patio. Cleanup should be easy with a shop-vac. And just think of the effect if I filled them with talcum powder. WOW! Sorry, but no steam engines used on this one."