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Pencil Ballista

14 Jul 2008
Progress: Almost finished

It was inevitable this would arise, after the piles and piles of office supplies artillery I've made before.

A Ballista is a kind of giant Roman cross bow. It consists of a frame with tensed rope instead of a bow, so it can be built on a huge scale. I was inspired after seeing a life size replica of one which shot bolts seven feet long!

Black and white photo of a model ballista
An idea of what they looked like

So here are some old photos of my early designs.

Pencil drawing of the planned ballista

A pencil drawing of the pencil ballista

The ammo could be either pencils, marbles or real darts. Depending on your source, Ballistas shot both rocks and bolts, so pretty much anything would do.

The rules I set myself were simple: The only materials available are elastic bands, pencils and paper clips. It took ages to cut through the pencils, so I ended up using a drill. And drilled graphite makes a LOT of mess.

And now for the excessively detailed making-of so far.

Pencils and paperclips and elastic bands
A paperclip, and a straightened paperclip
Pencil with paperclip wire threaded through
Pencils joined by threading wire through drilled holes
Pencils joined together
Arranging pencils for the ballista
Pencils arranged to form the shaft of the ballista
Pencil Ballista frame
Pencil ballista frame
Pencil ballista elastic bands
Pencil Ballista strung with nylon

I got as far in this construction to have a working model, but I dismantled it to try and wind the elastic bands tighter. The shaft also needs to be longer than I expected, as fully drawn it needs double the length of a pencil plus the length of the trigger part, which needs rebuilding.

There's so little to do to actually finish it, all I need is a spare moment...