The rope bundles are the main engine of the machine. The framework that holds everything together is about 24 ft long, and 6 feet tall.

The Scutula (Hole carriers) await their fate on a pile of rocks. The round donut was found in this shape at a scrap yard and is 1 inch thick. The green rectangular donut was torched out of some sort of factory floor support, and is 3/4 inch thick. (Also from a scrap yard.) These will become the major hole carriers for one torsion bundle. A matching set will be used for the second bundle.

Oops, we cut the holes in two of our hole carriers a bit large last year. Here Eric is adding a couple lbs of steel back onto the inside edge of the scutula prior to the milling operations.

Unfortunately the 1" thick scutula pieces that we had scavenged from the scrapyard turned out to be cast iron. This prevented us from welding up our rope bundles properly. Rather than replace them (with all the necessary machining tasks to the new pieces) we decided to bolt on some steel adapter plates (auriculae) that can be welded to the stanchions. Here we are drilling and tapping holes in the adapters plates to fasten them to the cast iron scutula.

Fitting adapters between the regulae and the bottom scutulas of the rope bundles. Here you can see the new adapter plates temporarily bolted in place.

We've finally started welding together the rope bundles. Here Eric welds a stanchion onto one of the 3/4" thick steel scutulas. Getting them to be perpendicular was a bit of a challenge, as the next step required a perfect fitting on a 6 inch by 10 inch area at the end of 6 feet.

Once the stanchions were welded to the steel scutula, we lifted that unit in the air with Dave's engine crane. We had to get the stanchions to fit perfectly onto the auriculae we built and bolted onto the cast iron scutula.

Since it was impossible (with the tools we had on hand) to line up the stanchions perfectly, we had to use a little persuasion to make them line up as we deemed proper. Here Kevin measures as he and Dave contemplate where the welds will go. You can see the car jack spreading the two stanchions apart to better line up with the adapters on our cast iron scutulas.

Huzzah! The rope bundles are complete! Dave and Kevin show off how they can disguise themselves as a rope bundle. Our rope bundle will eventually be about 11 inches in diameter, and almost 7 feet long.

Our rope arrived today! (10-25-2002). This is 1200 ft of 3/4" polypropylene wrapped in the original shipping packaging.

The Thursday night before the chunk we started winding the rope bundles. Here you can see that we used our pin holes to bolt the modiolii onto the machine while we started winding. In addition, you can see the small bits of chain welded to the end which we later used as hitching points while winding the rope bundles.

Here Kevin is keeping tension on the existing winds of rope while Jeff sorts out a tangle. The lines we wound in each rope bundle are 600ft long of 3/4 inch thick polypropylene.

Additional Pages
Mista Ballista : Modiolus and Epizygis	The Modiolus and Epizygis used in Mista Ballista account for a majority of the time spent. The size and detail needed to construct these items in a way that could reliably contain the force of so much rope worried us, and we over engineered them.
Mista Ballista : Rope Bundles (This Page)	The rope bundles are the main engine of the machine. The framework that holds everything together is about 24 ft long, and 6 feet tall.
Mista Ballista : 2005 Rope bundle Upgrade	At the 2004 chunk the main stanchions for the torsion frames were bent by the impact of the arms. You can see the animation of when this happened on the Mista Ballista Arms page.
Mista Ballista : 2006 Rope Bundle Reconfiguration	In 2005 we broke our fancy fiberglass arms. In 2006 we got the new carbon fiber arms and video taped them in action in the summer at our 2006 History Chunk. This led us to discover how much they bounced around the outer stanchions. We were getting multiple recoils after every shot, sometimes back at least 30 degrees. That was also just with 2000 lbs of pullback, which is much less than we expect to use in competition.
Mista Ballista : Frame	The framework for the Ballista had to be built strong enough to resist the pullback, and to hold up the 2500 pounds we currently estimate of our engine. It must also push it up 16 feet in the air!
Mista Ballista : Arms	Building an arm for a torsion machine this large has been very challenging. A list of our failures in this area might provide some hints on what not to do.
Mista Ballista : Trailer	One of our goals for the 2003 season is to acquire a dedicated trailer for Mista Ballista.
Mista Ballista : Mystery Parts	All winter during 2003 we have been collecting the parts we need to accomplish our 2003 chunk goals. Here are a bunch of pictures of these random parts. Can you guess what they are for?
Mista Ballista : Deployment	To travel to different chunkin' locations, we need to pack the system down onto our trailer. Deploying from the folded up position is challenging and time consuming, taking a day and a half at the 2002 chunk. This year at the 2003 Punkin Chunk, we were done in about 4 hours.
Mista Ballista : Torsion	Mista Ballista's engine operates with torsion from twisted rope bundles. One of the biggest challenges of torsion for this machine has been adding the twist. An onager is pretty straight forward in that a large lever and gravity can be used. With our ballista, the direction of twist is sideways, so alternate means of twisting is needed.
Mista Ballista : Hydraulic and Electric Power	Mista Ballista uses hydraulics for lifting the engine to a 45 degree angle for firing, and also for winding the cord bundles. We also like having electricity on hand since Mr. B has a tendency to break, and need on-field repairs. This page describes what we are using to power up the system.
Mista Ballista : Failed Arms	Building an arm for a torsion machine this large has proven to be very challenging. Based on the experiences of our competitors, who also keep breaking arms, we find that we are not alone in this dilemma.