Friday, March 23, 2012

Catapult Fully Functional... but not yet complete.

Weeks ago I posted my first blog post, about building a catapult (technically, it's a mangonel, I've since learned). Well, it's finally hurling objects at short distances (about 45 feet or so, with it cranked up at what I'd call "medium" tension).

Did we make it in budget? Sort of... Materials cost is just over 200 dollars. But labor is about 48 hours now, far beyond my initial estimates (10 hours). You could call that another 800 dollars at least, since most of the work was done as generously low-cost labor by a couple of friends.

But if I had to make another catapult  now, knowing what I now know, it would take maybe one day to complete it.

Lesson 1: Have the right tools. You need a good saw, not a battery powered one.
Lesson 2: Brace the base frame on either side of the twisted ropes whose tightly twisted form gives the mangonel its spring action. When those ropes are tightened, they have tremendous power, enough power to snap your whole wood frame if they're not braced with 4-by-4 wooden beams on either side of the rope.
Lesson 3: The mechanism which is used to twist the rope has to be very strong, made of heavy steel. Once again, the twisted ropes contain a lot of power. Make sure you have a heavy duty mechanism which can withstand the force as you crank the rope tight.
Lesson 4: Be very careful as you crank. Don't do it alone. You can easily lose a hand or an arm, and if the lever you're using hits you in the head, you will likely die.
Lesson 5: Use an old tennis raquette frame wrapped in a piece of leather for the "bucket" or "pocket" on the end of the mangonel's arm. Don't bother trying to make it yourself.

I'd say those 5 tips will save you half your time. The rest, you might have to learn yourself to really understand why it's more difficult than it might seem.

Special thanks to Kurt and Marshall for their labor on this excellent war machine. Now I can't wait to make it look really evil and use it in our upcoming film.

To get it firing stones long distances, at, say, 50 yards plus, it's going to need a thicker, more elastic rope and two strong bodies to crank the thing up.

Our first attempt at a catapult. I'm not disappointed, just more realistic now about what it takes. I highly recommend building one, if you have the means.

Here's a video of the catapult barely cranked up where the "bucket" breaks off:

Here's one of it shooting a bit harder...

I'll post another one when I crank it up to full power next week.

No comments:

Post a Comment