Trebuchet Diy

In this Instructable I would like to show you my attempt at making a Trebuchet.

I'm not going for a Trebuchet that looks like the original, It's more the concept of seeing if I can get the thing to work effectively and catapult something, the goal is not distance, more seeing if the principle works.

There are quite a few designs out there but the principle is the same, I have a few bits and bobs available without making any purchases so lets see how it turns out.

I will be using a combination of Table saw, Band saw, chop saw and other power tools and will take the necessary PPE precautions when working with such machinery.

Safety Goggles

Ear protection

Dust mask

With no further ado, lets see if we can launch one or 2 things(If it works of course)I've seen some which don't perform too well:( so fingers crossed.

Scrap bits of Timber.

Broom shaft.

CA Glue and activator.

Various drill bits.

Ball Bearings for ballast.

5mm allen head bolts and lock nuts.

Panel Pin.

From looking at various Trebuchet builds and with a basic idea of how the thing works its time to start my own build, I have various bits of scrap timber lying around so the first thing we need is a base.

I had a length of varnished plywood 15mm depth not even sure where it came from but this will be an ideal starting point, it was a bit long so I cut approx 100mm off one end.

For the 2 uprights I had a small length of 60 x 40mm which in itself was too bulky, so I cut straight down the middle and then cut one these lengths straight down the middle as well, lightly sanded these will form my uprights.

I noticed on some of the builds that there is a V shaped runway, the projectile runs along this before its sent into the distance, I too wanted a runway.

I had a couple of lengths of approx 20 x 3mm depth and cut these to length for the runway, for the bearers I just roughly marked out a V shape on some scrap plywood and cut these out on the Bandsaw, the band saw is coming into it's own with this type of build, its a quick and efficient way of detailing wood.

With the 3 V shaped bearers cut I used CA glue to adhere them to the runway slats and then CA glue to stick the runway centrally to the base.

The next task was to fix the uprights to the base, to achieve this, I marked off positions and drilled and countersunk the holes then using a square tacked them in place using CA Glue, before finally screwing to the base.

For the pivot point for the arm I'm using some 8mm chrome round bar, and for the arm I'm using a trusty broom shaft, this is drilled to accept the 8mm bar plus another hole to the rear of the this, this is for the cradle which carries the ballast.

To keep the arm central I cut 2 brass sleeves that go either side of the shaft and then CA glued the ends of the 8mm bar into the uprights.

To finish off the uprights and add strength to the build, using strips of pallet wood I cut to the size I wanted then using 1 Piece held it up to the upright and marked off both ends with a pencil, I cut on the band saw then used this as a template to make 3 more, lightly sanded they were then glued into position.

The next process is to make the cradle:

The Trebuchet needs a basket or cradle to hold the ballast, this needs to swing freely both under tension and then when the tension is released.

The shape for this one is marked out on scrap plywood and then cut on the band saw and using this as a template created the 2nd side, another piece of plywood was used to create a base then used 2 scrap pieces of pallet wood to make the ends, the pieces were all held together using CA Glue.

A 5mm hole was then drilled in either side to accept a 5mm Allen head bolt and locking nut.

To fix the cradle to the pivot point on the broom shaft, I made a couple of extenders, these were 100mm in length and cut on the bandsaw then the corners rounded and sanded 5mm holes drilled in each end.

The extenders were bolted to first the cradle using 5mm flat Allen head bolts and Locknuts and then a 70mm Flat head Allen bolts and lock nuts used to keep the cradle central.

Firing pin and string attachment.

On the end of the broom shaft, I drilled a small hole for a panel pin, this was secured in the hole with CA Glue, this is the firing Pin, then just adjacent to this and underneath the shaft, I drilled another hole to accept a screw in eye.

I now need some sort of sling, I had an old hessian sack, and cut one corner off this, tied some 1.5mm Black Waxed Cotton to each side of this, then for added strength applied CA Glue to the tied knots, I measured it out so the sling was at the extent of the launch area, one end of the string for the catapult is secured to the ring underneath the shaft with a knot then CA Glue for strength.

The other end of the string has an eye screw attached to it, and this in turn goes over the firing pin.

With everything in Place its time to test the Trebuchet:

For the first test, I loaded the cradle up with Bagged ball bearings, I had visions of these going all over the place if things went wrong, I was then thinking what I could use for ammunition, I had just the thing, a Ping Pong Ball:), again if something goes wrong I can handle a Ping Pong ball to the head.

I tried to make a bit of a trigger but it didn't work properly so I loaded the ball and applied tension, pulling it as far back as it would go I released it, guess what? it worked, ok the ball never had snow on it when it landed It didn't get that high:( But at least it worked, a few tweaks were needed, the 2 things you can adjust on this one is to add more ballast or bend the firing pin slightly, I did both and got results so time time to up the Anti and take a few pot shots at the Pop Pop boat.

Well as the story goes and the Video shows, I never actually hit the Pop Pop boat, but we got close on 3 occasions, this thing never went in the same direction twice, but at the end of the day its great fun messing with it, keeps me fit as well all the fetching of the ball etc.

I hope as always that you enjoyed this Instructable and thanks for Looking.