Pyramidal casting for a wire-drawing die
Casting a conical copper drawplate; ringed tongs, a wedge to clamp the die, and a force calculation
Headed 'On the pyramidal casting,' this page designs a conical wire-drawing die (trafila) and the apparatus to make and hold it. A ring is drawn at upper right and a geared bench with a screw fills the middle, shown in two views. The notes call for ringed tongs lined with continuous wicks to grip the cast piece, describe casting the pyramid from thin copper ('emar') over a rotating core, and add a wedge (conio) that clamps the drawplate n m. A calculation claims that with a base 4 braccia across and a cutting edge the size of a small coin, the edge gains a power factor of sixty-five thousand five hundred thirty-six.
On this page
Casting the pyramidal die from thin copper over a turning core
The pyramidal casting is made as shown in the margin, using thin 'emar' (copper) and coming out to any length desired; the material can be very fine, promising security and excellent permanence. The core (maschio) turns so it can be rotated for the convenient release of its material; alternatively a drawn copper tube filled with lead ('obnoip') is made in one piece and its core dissolved at the end.
Wedge clamping the drawplate n m
The wedge a serves to tighten the drawplate n m: it clamps the drawplate m with great power. The beams that serve as the handles of such tongs must be strong.
Ringed tongs lined with wicks
a b are ringed tongs (tanaglie anulate) lined with continuous wicks or tow. The ring always exceeds the cast piece by half a finger and embraces the cast piece by twelve fingers.
Force gained at the cutting edge
By calculation Leonardo finds that if the base has a diameter of 4 braccia and the edge of the pyramid is the width of a danaio (a small coin), the edge becomes more powerful by a factor of sixty-five thousand five hundred thirty-six.