Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. This list of materials is copied directly from my science fair project. It includes what I used at the time.

Author:Nilmaran Shazragore
Language:English (Spanish)
Published (Last):13 September 2005
PDF File Size:1.35 Mb
ePub File Size:6.38 Mb
Price:Free* [*Free Regsitration Required]

Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. This list of materials is copied directly from my science fair project. It includes what I used at the time. The lumber list is really long, but I think I bought somewhere around 20 8' long 2 X 4s, I'm not sure This still does not include the 2 X 6 pieces or any other pieces of plywood.

I would still recommend that you read through the list, and buy the lumber as you need it to avoid wasting wood. Buy 15 2 X 4s to start off with, then buy more later. Also, if I mention anything else in the instructable that I didn't mention here, let me know. Materials Lumber 2 segments of 6 ft.

This may need to be changed. These Are not included in the instructable because I did not think they were necessary. I might include them later. If you really want to include them, they should also be cut about 3 inches longer, until you know what to cut.

This might change depending on your weights setup. This is what fit for me. Also, 1 inch thick wood would would be stronger. Hardware about 2. Approx 25 ft.

One thick nail. This is the pin. I don't know what gauge mine was, I found it in the trash Buy one that is at least 4 inches. The thicker the better to prevent it from bending. You should also cut off the head if you keep getting downward throws no matter how you adjust it.

If you want a better pin system, look at the turnbuckle pin system here. I'll explain later I'm kinda adding these as I think of them.. Tape measure, ruler rubber mallet claw hammer um..

I think that's it OK onto step 1 the base Ok, so this is what the entire bulk of the trebuchet rests on. It's 6 feet long and 2 feet wide. And it is constructed with 1 X 6s That's its fault. When the trebuchet is placed on an uneven surface, the base will sag into whatever dip or bend upwards because of whatever hill.

This, in turn, changes the width of the drop channels to narrow BAD or widen usually better. Although 1 X 6s did end up working, 2 X 6s would have been more sufficient. Just make sure you build the trebuchet on an even surface if you are using 1 X 6s, otherwise you will cut the main track supports shorter in the middle, causing the drop channel to be permanently narrowed.

If this happens, use it on a hill or place two very thin pieces of scrap wood under the base, directly under the drop channels. That should bend it back upward. Yeah, this happened to me. Ok, now, the base is constructed using half- lap joinery.

For this you will need your circular saw , sander and the claw hammer if you don't have a router. A wide chisel would also work. You will need the two 2- foot lengths of 1 X 6 and the two 6- foot lengths of the 1 X 6. On each piece, mark 5. Make a square line across the flat side of the board.

Should be square to the length of the board, like a crosscut. Then, using the claw hammer, hammer out these slivers of wood. They should come out easily if they were cut narrowly enough.

Then, use the sander to sand it down flat and smooth. The first sketchup picture Sorry only have real pictures of the finished thing shows what it should look like when your done.

Male sure you always do these cuts on the same side. If you have a router, it would be easier to do this by just cutting away the material. Ok, now you need to flip over the long 6-ft. Use a forstner bit or any other drill bit and drill holes parallel to the length of the long 1 X 6 and near the inside corner.

This is only to coutersink the screws, do not drill the hole all the way through. Look at the pictures to see this; it's kind of hard to explain the placement in words. Then, obviously, drive in the screws. Before you do that, though, make sure that you are driving them in from the bottom. The bottom is the side where the 2 ft 1 X 6 overlaps the long 1 X 6. Lastly, make sure everything is square. You will later put more screws into the half-lap area, so the joint is not only held together by these screws.

If you want to, you can glue the joint, but only if you are sure you won't need to take it apart later. The base is finished.

For this step you will need four of the eight 3. This step is fairly simple. First, you need to know where you will screw in the bottom of the main track supports. Line them up so that their 1. The first picture shows this.

Ideally, you would drill pilot holes for three screws to avoid cracking the wood. For each track support, you should use 3 of the 2. Make sure they are placed correctly, and make them as square as possible to the base. The second picture shows what it should look like after they are screwed in. Now you simply lay the 6 ft pieces across the supports, lining up the edges, and drive three of the 2.

Mortise and tenon joints here would be best, but I didn't feel like they were necessary. I would still recommend doing one, though. Although they need to be lined up, don't worry too much about the squareness of the main track supports to the base, since that will be corrected by diagonal pieces, from the track supports to the track itself. So now we're going to add some extra supports that will prevent the 2 ft 1 X 6 from bending, Lateral support and extra track support.

Bending Braces. They have cutouts on them so that they can be screwed directly onto the base with their 2 ft. The cutouts go around the main track supports. It is later screwed through the base and through the main track supports. The first through fifth sketchup picture will show this. Diagonal Track supports.

These are the four sections of 1 ft, 5 in 2 X 6. If you want the diagonal to go exactly 1 foot out and 1 foot down from the corner, you need a more precise measurement, it's something like 1. Luckily, the exact size of these supports doesn't matter too much. Simply miter off each edge at a 45 degree angle, so that the piece is the shape of a trapezoid.

Again, the exact size of the support does not matter, but the long edge should be under 1 ft, 6 in. The placement of these pieces is shown in the sixth picture.

Basically, put them in the corner where the main track supports and the track meet. Put them in that corner, towards the inside. Again, the lateral placement in this corner does not matter as long as both edges of the diagonal meet evenly along the track and support. Use three screws in every place that the diagonal touches the track or support.

And lastly, for the extra supports, we have the lateral diagonal supports. These keep the distance between the two tracks from narrowing or widening. Unfortunately, there were some problems in the sketchup base that I made and could not be easily corrected that threw off a couple of measurements.

So, the lateral diagonal supports did not come out too well But I'm sure you'll get the idea. They are basically the same things as the 2 x 6 diagonals except they are 2 X 4 and they have more half-laps cut in them.


Floating Arm Trebuchet (F2K)

Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. SolidWorks was used here, although any CAD software or even a hand sketch would be ok. One advantage of 3D CAD was the ability to make an assembly and ensure a good fit for all the components, as well as smooth motion.


Floating Arm Trebuchet

There were four teams competing to see who could launch a cantaloupe the farthest. In my student group, Tesla Works, I have built a couple trebuchets before. A trebuchet is a type of catapult that uses a counterweight to engage the arm—which is attached to a sling—and launch projectiles. The design originated in medieval times as a siege weapon. Since the middle ages, however, engineers have developed newer, more efficient styles of the trebuchet.


Floating arm trebuchet




Related Articles