I got the chute installed. This is what the sling with the tennis ball will ride on.
Then I rigged up the cord for the sling and trigger. Everything is made with 3/16” nylon cord. For the sling, a length of cord run from an eyelet under the swing arm to one side of the sling. Then another length of cord runs from the other side of the sling to a brad nail on the end of the swing arm. The timing of when exactly the sling releases the tennis ball is adjusted by changing the angle of the bend in the nail at the end of the arm. You have to fire it in a trial and error method to fine tune the swing for maximum distance.
The trigger mechanism is a length of cord that runs from an eyelet on the right side of the frame across a nail on top of the swing arm with a ring tied on the other end. That ring sits between two eyelets in the left side of the frame. Another length of cord with a 2” cotter pin on the end of it passes though one of those eyelets, through the ring on the first cord, and through the other eyelet. When the cord is pulled, it pulls the pin out, releasing the cord that is holding back the swing arm, launching the tennis ball.
You may notice the sling lying on the right side of the trebuchet in this photo. It is a 4” wide piece of leather with a grommet installed in each end of it.
Then I slapped on a coat of poly and tried to test it. The problem was, I haven’t actually bought the tennis balls yet. So I aimed it across the road of my shop, where there is nothing but a deep gulley, and put a rock in it. I stood towards the side and yanked the pin. Then I run like hell when the rock launched in my direction. The small rock didn’t stay in the sling too well. After some thought on the matter, I determined you need a projectile about the size of the chute, so the side can keep everything together so it can leave the end of the chute and release properly. If you don’t, you do stupid stuff like have rock launched in your direction (he he).
Then I went to the back yard to see what else I could find. Nope. No tennis ball. A baseball is about the same size though. After careful consideration, my conclusion was that with the baseball being heavier than the tennis ball, it wouldn’t go very far, just will let me know that it works. I was wrong.
I tucked the baseball into the sling. I attached the other end of the sling over the nail. I got back. I yanked the trigger cord. The baseball sailed over the deep gulley. It flew staight across the neighbor’s yard. The last time I seen it, it was going into the deep woods, the one’s that are overrun with cudzu vines, on the other side of the neighbor’s yard.
There will be no more posts on this blog series until I can get some tennis balls and take the trebuchet to a safer location to fine tune it for distance. I need to get somewhere that I won’t be losing all my kid’s toys.