Instructables
Picture of Lashed Trebuchet (1/5 scale)
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This is a scale model of the Trebuchet I hope to build with my son's scout troop this year. It is made with 6, 4ft dowels  5/8 inch in diameter. Using 1/8 inch jute twine for all the lashings, Only the launching plank is  glued, all lashing are standard boy scout square lashings 3 wraps and 2-3 fraps each . There are many sites to show you how, look up the inside outside rule, this will make the lash as tight as possible.  Each lashing should take about 4ft of twine, 

It consists of 2 A Frames with dual support along with t buttresses / stanchions  on each side to keep it from racking.

The throwing arm is 25 inches with a hole drilled at the 5 inch mark for a 1/4 inch steel bar, this arm currently support a counterweight of 10lbs.  The throwing basket is duct tape reinforced with a piece of fiberglass cloth. The escape mechanism is made of a coat hanger and a key chain ring. As of right now I do not have a release mechanism (works fine by hand the full size trebuchet will have to have one). 

Enough prep, onto the build


 
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Step 1: Materials and Cutting

Picture of Materials and Cutting
Materials:
6     5/8" x 4' dowels (there is some waste about 2ft when  I was done.

Cutting:

6     18"   -  3 for each A frame, 2 for the frame and one for the lower support
6     12"   -  2 for the upper A frame supports and 4 for the stanchions. 
2     24"   -  Support base to hold up A frame and provide a base for plank
1      1 1/2" x 14" x 1/4" launching plank (mine was a scrap piece of molding)  
1    25"   -  throwing arm

Jute Twine:
100'  of 1/8 inch jute twine or alike each lash should take about 4 ft +

Head of Arm  Release 

4" from coat hanger
1  Old key chain loop about 1/2 inch in diameter.

Throwing Axel
~ 9" 1/4" steel rod 
Drinking straw
4 Nylon Washers 
2 1/4" end caps

Basket

Duct tape multiple pieces:
5" x 2 in.
Fiberglass cloth ~ 5" x 2" to strengthen the tape.

Zip tie and electrical tape to hold Arm release. 


Tools 
Hand or Chop Saw
Pliers and Cutters
1/4 inch drill
 
old_alex (author) 11 months ago
I have throwing videos they were before got pro status and could not post them. The arm is easy it the throwing rope / basket which is hard. The arm pole has 3 holes in it one for the axle, one for the counter weight and third for the trigger. Looking at the pole standing on end, 1 inch from the bottom for the weight, 5 inches from the bottom for the axle and 3/4 inch from the top for the trigger.

The basket in my case was fiberglass cloth covered in duct tape, the twine is then tied to that, it requires adjustments to get the lengths and tie off points correct. I am lacking pictures of this step but the completed basket can be seen in use in the top picture (missing the ramp this was my first test shot) and others. I will try to post a video (I think I still have it).

I am an engineer by trade and may have assumed a working knowledge of trebuchet physics and construction.

Jesse1011 months ago
Is there a video for this somewhere? The instructions are nonsensical in some Steps. I am a little confused in constructing the throwing arm. Thanks much!

Dave
Hepkess1 year ago
I had no idea what a Trebuchet was. I Googled it.
http://en.wikipedia.org/wiki/Trebuchet
...
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Biggsy3 years ago
Nice trebuchet design :D I quite often make miniature ones... have a look at my i'ble on them it may give you some inspiration

High Five for you

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