I fear I am dangerously close to knock-on-wood territory. But I also want to show off a little bit. I’m getting close to finishing this project so I figured I’d make a post to document the build.
First steps, somewhere around 7-10h of cad. Here’s where my progress is so far.
The keen-eyed among you will I’m sure see a ton of similarities between this project and the fabulous Tom Stanton whipper trebuchet. And I’m okay with that. Notable differences include mainly the arm, which in mine is a 1m long 32mm OD carbon fiber tube.
The primary construction will be 2x4s and 1/4" Baltic Birch gussets. Held together with M8 bolts and some glue potentially.
Motion components (shafting, bearings, hubs) are what the company I work for makes, so that’s an easy one.
in personal news, I finally took some time off this weekend. So the next two days I have a couple of Halloween wooden swords to finish up, and hopefully get a good amount of progress done on this project.
4 hours of shopbot time and 26 parts later, I’ve got everything to be CNCed done. A few prints need to happen over night before 2x4s get cut, and things get assembled tomorrow
Looks cool. What keeps the arm in the middle of the rod? How much weight do you expect it to be able to throw? Is the rod big enough to keep from getting all spaghetti-like? Will this answer the ago old question about whether cats can really fly?
Got some assembly done today, one side of the frame and arm completed (mostly) and even got a quick test of the mechanics. Found some issues that need fixed (you’ll notice it sticks after over extending after “firing”
I’d suggest some soccer fields, when there are no games. I know Haysville has Dorner Park that’s pretty large and not too busy. https://www.haysville-ks.com/dorner-park
Ended up going just across the street, worked great! My furthest shots ended up about 120 yards from the trebuchet. It sure looks like there’s a ton of energy left on the table with this setup. More tuning required!
Unfortunately, my second shot with 25lbs of weight broke my PC printed endcap along layer lines. A stronger print orientation and more walls seem to be required. along with a less grippy sling. https://photos.app.goo.gl/nTztYFrfTdYERf95A
I reprinted on its side, with double the walls and 3x the infill. If this one breaks I might have to take advantage of my metal lathe class on Thursday and machine one out of aluminum:)
