After discovering that the double sized-machine I had built for the Carnegie Science Center was, in fact, too big, I went back and divided all my measurements in half.
Anyway, at this meeting, Cathy, the program director, was looking for something neat to do as a lobby activity.
By the next week I had searched the web and discovered several sites with information on trebuchets. It launched the racketball like an overhead serve, the ball ricocheted off the grass about 25 feet away and bounced off into the darkness.
By late monday night I had repaired the fulcrum with a half inch rod and made other adjustments. As impressive as my machine was, it was also intimidating and its great range made it somewhat unsuitable for use indoors.

Adjusting the sling and such took a little longer but it wasn't long before I was chucking water-filled ping-pong balls about 20 feet into a garbage can. The Gray Company had a marvelous page and had a nice side note on a machine named "Cheesechucker." I thought it seemed a little small, considering mine would have kids clustering around, eager to be next, so I doubled the dimensions. The quarter inch threaded rod I had used as the fulcrum had bent noticeably and it shimmied wildly.
Two 20-oz pop bottles filled with lead shot as the counterweight and a foam planet ball-thing as the projectile, purchased specifically to be hurled.
There were very few places inside the science center with enough overhead clearance for a decent throw.
The overnighter program involves some 400 kids from school groups, scout troops and the like, spending the night at the science center.

I even drew up a target, a snooty Frenchman a'la Monty Python and the Holy Grail, to set upon the parapet.
The person in charge of lobby activities at the science center's overnighter programs wanted several so I built three more. By adjusting the mass of the counterweight, one could get the projectile one floor up and over the rail.

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  1. Vuqar

    Woodworking, should you intend to have a set of solid and easy woodworking the vise or vises you'll.


  2. BubsY

    Talent level i want to be in in 30 years time, but read plenty about DIY woodworking projects.



    Woodworking venture that is more involved and other initiatives.