I want something small that will throw a golfball or tennis ball an
impressive distance. So I was thinking maybe a "King Arthur" style
trebuchet (with a fixed axle, not floating.)

Has anyone here built something like that? Maybe I'm at the wrong
group, but I don't think so.

How important is it to be able to adjust the amount of counterweight? I
was planning to use a sledgehammer for the hanger arm and counterweight.
Or maybe a beer can sized block of lead -- about 8 to 10 pounds.

I assume the throwing arm needs to be as light as possible, especially
towards the end.

No idea how one adjusts the sling.

Best regards,
Bob

My Boy Scouts and I build a pumpkin chucker every year around halloween and
go to Delaware to the contest down there.

Lots of fun...

Never won but there is a lot of satisfaction in tossing a 10 inch pumpkin a
50 to 75 yards.

We started years ago with a traditional catapult but could not get the
distance we wanted.

Got a science and physics teacher involved (my son) and have made
considerable progress the last year or so with the trebuchet style by
playing with the arm and sling length.

This year we tilted the mechanism off the vertical and gave it kind of a
sidearm swing. Longer travel, more velocity more distance. Accuarcy
suffered a bit but that is a problem for next year.

Do a google search on pumpkin chuckin or chuckers and see what you find.

There are also some neat things you can do with PVC pipe and hairspray in
the form of potato cannons. You can also google them.

You could do some damage with a golf ball.

What kind of distance are you looking for?

I was asked this year whay is the secret to being a successful Scout leader
and keeping the boys involved.

My answer was projectile weapons and thinking like a 4th grader.....






"zxcvbob" wrote in message
...
I want something small that will throw a golfball or tennis ball an
impressive distance. So I was thinking maybe a "King Arthur" style
trebuchet (with a fixed axle, not floating.)

Has anyone here built something like that? Maybe I'm at the wrong group,
but I don't think so.

How important is it to be able to adjust the amount of counterweight? I
was planning to use a sledgehammer for the hanger arm and counterweight.
Or maybe a beer can sized block of lead -- about 8 to 10 pounds.

I assume the throwing arm needs to be as light as possible, especially
towards the end.

No idea how one adjusts the sling.

Best regards,
Bob

On Sun, 21 Dec 2008 21:57:27 -0600, zxcvbob wrote:

I want something small that will throw a golfball or tennis ball an
impressive distance. So I was thinking maybe a "King Arthur" style
trebuchet (with a fixed axle, not floating.)

Has anyone here built something like that? Maybe I'm at the wrong
group, but I don't think so.

How important is it to be able to adjust the amount of counterweight? I
was planning to use a sledgehammer for the hanger arm and counterweight.
Or maybe a beer can sized block of lead -- about 8 to 10 pounds.

I assume the throwing arm needs to be as light as possible, especially
towards the end.

No idea how one adjusts the sling.

Best regards,
Bob


I've built several, from "peanut throwers" to one that has a 16 pound weight
(bowling ball) and throws a 1 pound fishing weight..

This is where I got started:
http://members.iinet.net.au/~rmine/gctrebs.html

my first one was a clone of their "cheese chucker"

Don't know about the sledge hammer arm, might want to read a bit first..

I found that the swinging basket for the counter weight not only makes weight
adjustment easy, but provides a really good relief for the force generated on
the frame..
Early trebs had either a swinging basket or wheels of some type.. Otherwise,
they had to re-aim every shot due to movement of the entire treb on the forward
stroke..

2 basics...
The pivot on the arm should be at a 4-to-1 ratio, or 20% from the front end..
At rest, the throwing arm should be at a 45% angle to the "floor" of the treb..

I would have been much happier with my first couple of trebs if I'd paid
attention to those 2 numbers!
HAVE FUN!


mac

Please remove splinters before emailing

zxcvbob wrote:

I want something small that will throw a golfball or tennis ball an
impressive distance. So I was thinking maybe a "King Arthur" style
trebuchet (with a fixed axle, not floating.)

Has anyone here built something like that? Maybe I'm at the wrong
group, but I don't think so.

How important is it to be able to adjust the amount of counterweight?
I was planning to use a sledgehammer for the hanger arm and
counterweight. Or maybe a beer can sized block of lead -- about 8 to
10 pounds.
I assume the throwing arm needs to be as light as possible, especially
towards the end.

No idea how one adjusts the sling.

Best regards,
Bob

I saw a documentary a few years back on a competition between two teams
building (full size) trebuchets. The more successful design used a swinging
box for a counterweight which allowed them to add or subtract sand to vary
the weight as needed. They also found that being able to bend the hook on
the end of the throwing arm to adjust the release point of the sling was
important.