Ethan's Trebuchet Project

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.

Thanks for following along!


This is my follow dot. I have nothing to add I’m just curious. :black_circle:


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 :sunglasses:


Nice. Very cool. Thanks for posting!


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 can’t decide whether she looks impressed or not! I think it’s cool though!


@whateg01 - sounds like you may have to build one to see if you can make it cooler. :wink:


That’s really cool and has a nice sound to it. :+1:


The first 5 test fires commenced this fine evening!!!

This thing is awesome!!! I’m so excited to do some much-needed tuning tomorrow.

Any suggestions for where I can shoot this thing?? I think once I have tuned this beast it’ll easily outshoot the space we have at the Makerspace.


How far do you think it will shoot?

I honestly don’t know. I could see it going a few hundred yards

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.

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Unfortunately, the satalite imagine isn’t up to date.

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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.

But this thing rocks


3d print with an engineering resin or recast the fdm print to get rid of layers.
Or, ya know, you could just lay the whole thing up in carbon fiber! :rofl:

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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:)


Some small upgrades today, replaced the 3d printed release pin with a turned aluminum one


Our badass new paint booth holder things are getting some use this weekend :joy::sunglasses: