does anyone know how to built a catapult from wood with directions and measurements?

Answer 1

http://www.trebuchet.com/plans.html

Answer 2

1

Answer 3

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Along with stone, mud and animal parts, wood was one of the first materials worked by early humans. Microwear analysis of the Mousterian stone tools used by the Neanderthals show that many were used to work wood. The development of civilization was closely tied to the development of increasingly greater degrees of skill in working these materials.

Answer 4

I've got some wood. Send the directions & measurements and I'll see what I can come up with.......

Answer 5

http://forums.bit-tech.net/showthread.php?t=111548

sounds like an AP Physics project -- right?

Answer 6

There are many types of catapult. Firstly, you have the trebuchet, which I make by building a pair of A-frames, joining them at the bottom, adding an axle, and runing that axle through an arm with a weight on one end, closer to the weight end than the non-weight end. I like a 4:1 ratio of lengths. Put a wood screw in the top of the nonweight end, tape a golf ball to a loop of rope, pull it back and let 'er rip.

Or you can make an onager. This type of catapult uses two T-shaped frames, equally spaced, with diagonal bracings on one end. Drill two holes before the bar of the T, and stick an axle between them. Run elastic between the holes around the axle, then twist it until taut. USe the same setup with launching as described with the treb.

For a more specific setup, I offer directions for a treb I built recently. Have fun!

The Twenty-Dollar Trebuchet

The purpose behind the $20 trebuchet was to create a working trebuchet for less than hundreds of dollars to determine optimum variables for sling length and so forth. Accordingly, it is a minimalist design, and uses only essential components. This in turn requires a bit of inventiveness, but it still works, and in my opinion it works well.

Parts List:
Three 2-foot 1/4th inch square-section dowels.
One 3-foot ¼ inch diameter round dowel
A box of #6 1 ½ inch wood screws
Eight 1/8th inch ID, 1-inch OD fender washers.
Seven 1-inch diameter by three-inch long zinc repair nuts (big hollow zinc cylinders)
Two zinc flanged nut sleeves ( I dunno the real names, they’re a tube of metal, threaded on the inside, with a collar on the front of the outside. The collar has sections bent inward, along the collar, to form teeth-like projections. Get the 1-4th inch ID ones.

Tools list:
Phillips Screwdriver
Saw (preferably a standard toolbox saw, but I’ve used a coping saw as well)
Drill with bit suitable for drilling pilot holes for the wood screws
Hammer (optional, but recommended)
Sandpaper

Instructions:
Start by taking all seven repair nuts and putting them together in a honeycomb fashion- 2, then 3, then 2, butting the hexagonal sides together squarely. Your objective is to build a frame wide enough to allow this structure to pass through it. Try 4 inches wide. Cut two 4-inch sections from one end of the round dowel. Square cuts will save you a headache or two but are not essential. Set them aside

Now you will build the actual A-frames. Cut two of the 2-foot beams exactly in half. Again, square cuts are nice, but not essential. Butt two of the pieces together, so that their end is a ½ by 1/4th inch rectangle. Set a third piece so that it runs lengthwise along this rectangle, with the ends square. Mark the midpoint of the innermost piece, and run a second line along the midline of the beam. You will drill at the intersection of these two lines, so that you could join two pieces end-to-side, and one would overhang the other by 1/4th inch.

Now to the actual drilling. You are dealing with really small bits of wood here, so be careful, but don’t worry about squareness other than eyeballing it. Drill a pilot hole at the intersection of the two lines, fully through the board. Now put a wood screw in that hole, and line the other side of the hole up with the midpoint of the end of another 12-inch piece. Drive the screw through both of them, so that you end up with a L-shape, but with a 1/4th inch overhang on one piece. Make two such frames. Make sure the edges are flush, and hammer a flanged nut sleeve on the inside of the corner thus formed, so that one “tooth” of the nut ends up in either piece of wood. You should have a metal sleeve running along the width of the wood, so that if you hold the piece up like a real “L”, you can look down the sleeve. The sleeves are the axle holders.

Now drill holes 1/4th inch in from the unattached ends of the frames, parallel to the sleeve. Put wood screws in the holes, and screw the frames to the ends of the 4-inch dowels, making sure that the two are lined up right and that the flanges of the sleeves are pointing outwards. You should end up with two parallel open-based right triangles.

Now onto the arm. Make a mark 6 in. from one end. This is where you will eventually put the axle. Now mount the weight.

Mark 12 1-inch sections on the third square-section dowel. Drill a hole in each, about 2/3rds of the way from one end. Then cut them, making 12 1-inch sections of wood with a hole near one end of each. Set 11 aside.

Slide a single repair nut onto the dowel, and stop it about 1 to ½ inch from the end. Now pick up your wood piece, and put a wood screw through it. Now screw THE END OF THE WOOD FARTHEST FROM THE SCREW into another repair nut, stopping when the screw is almost at the nut. Now butt the non-wood end of the nut against the nut on the dowel. While holding them aligned like that, screw the screw in the block into the main dowel, so that the two ends of the repair nuts are drawn together. Grab another nut and piece of wood, put a screw through the wood, and this time put the screw and block into the main dowel such that the nut is drawn snugly up against both other nuts. You may find it easier to use the block to turn the screw, rather than the screwdriver, and to remove the nuts while you screw it in, then replace them afterwards. Repeat with all the other nuts. You will end up with six blocks of wood held some distance away from the dowel, like a six-spoked wheel, and a nut on each. The outer nuts are trapped by the blocks, the inner nut by the sections of the screws. Now put a block/screw into the tops of the outer six by much the same procedure, except now you must screw the block in without the screw, and then wait until the hole in the block is perpendicular to the surface of the dowel before screwing it in. You will end up with two sets of six blocks trapping six repair nuts, with a seventh in the middle. That’s your counterweight.

For the axle, take the rest of the third dowel, and hold it against the frame, across the two triangles, with one end flush with the outer edges of the frame. Mark the inner edges of the frame and cut along them, to produce one little block and a piece that just fits in between the frames. Use that piece to cut another piece of the same length, and cut the rest of the dowel in half. Put the two longer sections and one of the halves you just made together, stacked end-by-end, with the long dowels on the outside and the three bases flush. Drill a hole down through the three, near the middle of the long pieces, and put a wood screw through it, then put the other short piece flush with the other ends of the long pieces, to make a bock 3/4th inch tall with a section cut out of the middle. Slide this onto the round dowel, on the end without the counterweight, until you hit the 6-inch mark. Drill down through the middle of the long dowels and the middle of the round dowel and put a wood screw through it, so that the arm is secure to this stack of wood rectangles. Sand the ends of the rectangles a bit.

Now put a fender washer on the end of a wood screw, then put the wood screw through the sleeve, collar to between the frames, add another washer, and screw the wood screw into the end of one of the middle pieces and screw it in just a hair short of tightly. Repeat on the other side, so that the wood rectangles are hanging from the frame by the screws.

One last step. Put a wood screw into the top of the throwing arm, leaving the head sticking out above the end. Now take the extra washers and put them on a loop of string, hook the loop over this screw, pull the arm back, and let it fly. To recap, you just made a working medieval siege weapon model out of dowels and wood screws, sticking a bunch of zinc crud on one end and securing it by a flimsy set of wood scraps, and rotating the whole thing on a square axle, with wood screws as bolts. Yes, that does misuse nearly every component. But hey, this thing will launch a golf ball taped to a loop of string ten feet with a little tweaking.