Instructions

The Base: build the triangular wedge that is the base by cutting sticks and lashing them together with rubber bands. The base shown is 20” wide,  7” deep and 12“ high. Put the sleeve on the topmost crosspiece during construction. The throwing arm will be attached to the sleeve later.

The weight – make this by placing 1-1/2 pounds of pebbles into the sock and then knotting its top and cutting off the floppy bit above the knot. Tie a twin loop of kite string under the knot. This will be used to attach the weight to the throwing arm. 

The Throwing Arm – the arm shown is 17.5“ long. Carve one end to a smooth peg as shown below. The looped end of the sling will go over this peg. Tie the weight .5 inches from the other end of the throwing arm. Leave about 1” of string between the arm and the weight bag, since the weight is supposed to swing below the throwing arm. Don’t make the string too long or the weight will touch the base and mess up the shot. Lash the sleeve to the arm 2.5” from the weight end of the arm as shown below.

Sling – made from two pieces of kite string and the denim square. The length of the strings affects the range of the device. The length shown here is 9 inches from knot to knot. Tie strings to opposite corners of the denim patch and then trim away the excess denim at the other points of the square. Make a loop on one end of the sling that just fits over the peg carved on the end of the throwing arm. Tie the other end of the string just above the peg as shown. Take care that the sling pocket is evenly closed when the machine is cocked and ready for firing, else the ammo will tend to come out of the pocket prematurely. 

Trigger – a rubber band attached to the throwing arm that wraps around one of the cross braces of the frame and loops over a bud or is jammed into a slit in the frame. Releasing the bud/slit end of the rubber band causes the trebuchet to fire. See photo below. 

Paper – put the paper beneath the trebuchet as indicated. This allows the pocket to slide without bumping at the start of a shot.

List of Materials

12 Sticks about 20” long and 3/8” in diameter – I used stiff sticks cut from my privet hedge, but any stiff sticks would do. Dowels would work fine. Cut the sticks to size as you construct the treb.

30 rubber bands – for the lashing the frame together and for the trigger.

Sleeve – this fits over the top crosspiece of the frame. The arm is lashed to this. The sleeve allows the arm to pivot freely and can be made by chopping the top off of the top of a fat marker. Any other piece of hard plastic tubing would work just as well.

Kite String – for attaching the weight and for the ropes of the sling.

A Sock – to hold the stones to make the weight.

1.5 lbs of Stones – to put in the sock.

2.5” square piece of denim – to make the sling pocket.

A piece of paper – to make the slide that the sling pocket slides along at the start of each throw.

M&M’s with Peanuts –the ammo