Some time when I have more time, I may try and check whats up with that, since I don't see any updates on the issue in almost a year.

now as far as the hurl.org, i tried that but there didnt seem to be a way to register, and i crawled into the help section, seems to say new user registration is disabled… is there a secret trick?

I'd guess you could get some more range with a lower area sling. It looks like yours has quite a lot of drag. Tuning looks pretty good, but I haven't worked with an F2K personally. I can't say for sure, but maybe a higher arm ratio might have helped get some of the counter weight energy out before the very bottom, for perhaps better range and less stress on the counterweight bar. Thats mostly a guess on my part though.

Note that the energy that went into bending your counterweight bar (assuming a stronger one, and proper tuning) could have gone into the throw.

A forked SA (put some of the weights in the middle) would have reduced the stress on the counterweight bar quite a bit, which looked like it ended up being the limiting factor. Its also possible to spread the counterweight across multiple shorter bars, which can make finding strong enough bars easier.

Your trigger design is interesting. I haven't seen one like that before, but looks like it does its job. Well done and I'm glad you guys had fun! Thanks for sharing.

Its mostly just me on the forums here; there is a much larger and more active community of even more knowledgeable folks over at www.thehurl.org forums.

search this string in youtube, please.

the link above is a series of fires with a treb the Cal Lab built in our off-time built for a Subbase New London Morale boosting event.

We had a ton of fun doing it. Especially since we all work in the electronics field and got to wrap our heads around a mechanical, physical problem.

Throwing arm is 8 ft. 105" weight drop of 195 lbs (I think underpowered but out bar was 1/2" blackiron pipe, maxed out). axle is 2.75 feet from weighted end. After tuning (you can see a couple shots go not so well in the first part of vid) sling length was 6 ft., release pin at about a 50 degree angle. Max distance was 67 yards by laser rangefinder and spotter.

So it was the first time we did something like this, and we got outshot by only one of the other trebuchets, who had the full 15 ft throwing arm and 750 lbs of counterweight allowed in the rules, not too bad.

Wanted to share this beast and look for some constructive criticism. enjoy, and fire away.