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Step 2Throwing arm
Next I created the throwing arm. I took two 50cm wood strips (1 cm thich, 2cm wide) and planed a taper to the ends so that I could form an A-shaped form.
First I drilled the axle holes. This is an important step since it finalizes the length of the throwing arm and dictates the optimum size for the ammo. My throwing arm is 50 cm long. The axle hole is 36cm from the arm tip and the weight fasteners are placed 13cm fro mthe axle. 36/13 gives a 2.7 ratio for the arm, which is probably a bit too small. When measuring the hole, keep in mind that the weight must be able to swing below the axle without hitting the base. Again, remember that it is easier to make something shorter than longer.
After drilling the axle hole I inserted the spacer into the holes (the spacer sit quite tightly in the holes) and glued the tapered ends. The spacer kept the holes aligned properly. After the glue had dried (or cured, since I used epoxy) I glued in the horizontal struts. After the gluing was finished I drilled a hole for the sling release pin axle to the arm end. Then I took a narrow saw and cut a slot along the glue joint for the sling release pin itself.
In the picture can see th finished trebuchet, but don't jump ahead yet. I will next instruct you to trim the chain and seat stays and build the wooden base.
First I drilled the axle holes. This is an important step since it finalizes the length of the throwing arm and dictates the optimum size for the ammo. My throwing arm is 50 cm long. The axle hole is 36cm from the arm tip and the weight fasteners are placed 13cm fro mthe axle. 36/13 gives a 2.7 ratio for the arm, which is probably a bit too small. When measuring the hole, keep in mind that the weight must be able to swing below the axle without hitting the base. Again, remember that it is easier to make something shorter than longer.
After drilling the axle hole I inserted the spacer into the holes (the spacer sit quite tightly in the holes) and glued the tapered ends. The spacer kept the holes aligned properly. After the glue had dried (or cured, since I used epoxy) I glued in the horizontal struts. After the gluing was finished I drilled a hole for the sling release pin axle to the arm end. Then I took a narrow saw and cut a slot along the glue joint for the sling release pin itself.
In the picture can see th finished trebuchet, but don't jump ahead yet. I will next instruct you to trim the chain and seat stays and build the wooden base.
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Jun 3, 2009. 7:55 AMchromedonut
says:
This is great. I've always liked hurling machines AND repurposing junk around the garage. This does both with one SWOOP!
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