Trebuchet – Firing Pin Mechanism

12 11 2008

img_0080I finished building the firing Pin Mechanism for the trebuchet.  It’s pretty simple.  There are three eyelet hooks; one on the throwing arm, and two attached to the frame.  I had to cut a slot into the trough so that the eyelets could be very close together. The photo below shows what it will look like underneath the trough.

I purchased a large 8″ nail that will act as the firing pin.  I’ll get a photo of that up here soon.

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The Next Project – Pumpkin Tossing Trebuchet

14 10 2008


So with the holidays coming around like Halloween and Thanksgiving I was interested in a project that would give tribute those great days, all the while sewing seeds of flaming pumpkin destruction. I’m not exactly sure why I decided on a trebuchet, but I’ve been interested in catapults and such since I was a little kid.  Now that I am bigger (but still very much a kid) I get to build my own medieval siege weapon.

I started thinking about this project around October 1, 2008.  I quickly realized that pumpkins are going to be gone very soon and that if I want my chance to chuck a pumpkin I’m going to need some help.  So I enlisted my friends who were all to happy to join the my mad laboratory team.

Trebuchets are very simple looking devices.  All they have is a counterweight that drops and whips a sling around tossing the contents inside.  During the medieval times they would toss all sorts of stuff at the castle walls like boulders, dead horses, etc.  We aren’t going to be tossing anything like that.  Just pumpkins, and maybe an ocassional flaming pumpkin.

Even though they are simple in concept.  The design is very complex.  For example, the counterwieght should be about 100 times heavier than the object you are tossing.  So our goal is to toss a 6 lbs pumpkin about the length of a football field.  That means our counterwieght has to be 600 lbs.   That’s pretty heavy stuff.  When you start swinging 600 lbs around you are going to be generating a LOT of forces.  That means that the axles that have to be VERY sturdy.  So on and so forth.

Other Resources

Trebuchet Design

Cement Blocks

Counterweight

Sizing the Axle (Part 1)

Sizing the Axle (Part 2)

A-Frames

Car Throwing Trebuchet

Cool Trebuchet Pictures

The bucket





The Next Project

13 10 2008
A Cement Block weighing about 200lbs

A Cement Block weighing about 200lbs

A Cement Block weighing about 200lbs

A Cement Block weighing about 200lbs

I’ve being a new journey with the help of some of my friends. We are going to build something really big. It’s going to need 3-4 of these 200 lbs blocks. These blocks were very easy to make. The first step was to create a mold that would be able to hold a 19.5″ x 21.5″ x 4″ cement block. I made the mold of of 2″x6″ and whatever piece of wood that I could drill to the bottom. Use wood screws to secure the wood in place.

The next step is to mix the 2 bags of cement. I’ve never mixed cement before so I’m not an expert, but according to the bag you slowly add water to the cement mix until it has a nice “plastic feel” to it. I’m not sure what that means, but I’m pretty sure I over watered the cement.

Next shovel the cement into the mold, and wait. The next day the cement will be dry enough to walk on, but it will be a couple of days before the cement is completely cured.

If you are still reading this post, then you are probably interested in why I am making cement blocks. It also has to do with the upcoming holiday’s, Halloween, and Thanksgiving. I mean that in the loosest sense of the word.

I’m going to be revealing a little bit at a time as the next month passes by. I’ll tell you what I can without ruining the surprise.

GOALS:
It will be finished by November 15th.
Keep it under $200.
Be able to _______ a pumpkin __________ far.

Other Resources

Other Resources

Trebuchet Design

Cement Blocks

Counterweight

Sizing the Axle (Part 1)

Sizing the Axle (Part 2)

A-Frames

Car Throwing Trebuchet

Cool Trebuchet Pictures

The bucket