In 2008, Dave devised a new system for managing the torsion in Mista Ballista with his friends Karl Hamm and Kevin Cheney. This represents a large investment in our machine in these custom parts.

Fresh from Martin Sprockets, 4 large sprockets arrive on a pallet in Dave's truck, ready for modification. They are series 140 sprockets milled from 1" thick plate.

We then extracted these 2x5 solid steel beams from Dave's stash. (Dave is the only one I know who might stash such a thing in case they ever come in handy.) These will be converted into brackets that will hold the epizygii.

Also in the mix are these shiny donuts. These were recently milled out of a 1.5" thick x 16" diameter billet of steel, and are to be welded to the bottom of our giant sprockets. These will fit into the scutula plates.

In this picture (taken by Dave) we see a wooden template fit to the center hole of the sprocket. The shiny donut is fit onto that, and the donut is then welded onto the sprocket.

The center of the sprocket was then cut out, and the welded hub gained a special groove the correct size to accept a layer of oil impregnated nylon which will be used as a thrust bearing. Next to the complete modiolus are the 4 very large epizygis made from the 2x5 stock Dave had brought. They were milled to a 1" radius to make our rope happy.

Here Roger is roughing out the oil impregnated nylon discs. These discs will later be set onto a lathe, and cut down to exactly fit the grooves in the modiolii.

Trevor helps out by cleaning the scutulas on Mr. B. When using oil impregnated nylon, you don't want to have any grease on the surface, as it inhibits the ability of the nylon to do it's job. Getting these surfaces clean was a big job after several years of using a metal-on-metal grease bearing surface.

After trimming the nylon down on the lathe, we get a perfect fit into the bearing groove of the new modioli.

The new modiolii were milled on a CNC machine whose long reach and associated deflection resulted in a slightly tapered hub. Our scutulas had a nice straight internal bore. Several hours of careful grinding were needed for each scutula hole to get the new modiolii to fit without seizing.

We then assembled the new modiolii, now each fit with an epizygis, and epizygis holders. We used a big fat strap to connect the two sides to hold everything in place while we try to fit stuff together. The epizygii are bolted on the sides, but the load is taken by the face of the modiolus.

The modiolii were bolted into place for the trip down to Delaware for the 2008 chunk. In this picture you can also see the wooden shims we made. The shims are to prevent the rope from splaying during tensioning. If the lower level of rope were to splay, then the upper ropes would sink in. This would make the bundle looser, and decrease our available power.

Visit the 2008 Chunk page for details on the final build out to get these modioli working for us. Also see the Torsion page for details on how these modioli work for creating torsion for Mista Ballista.