Belt Making

Two and a half yards of 14 oz. (0.017") reinforced vinyl sheet are laid  out on the living room floor. A 6.5" wide strip is marked off for cutting.    The strip is cut off.   (Avoid longitudinal cuts that slit the longitudinal reinforcing fibers.) Then it is mounted on the van de Graaff with the upper and lower bearing holders set at mid-position. A black mark (at bottom of photo) shows where the overlap will produce the correct belt circumference when overlaid with the other black mark (above the scissors). A 10 degree bevel is also marked and cut on each end (use a protractor or count squares)

The belt is washed with scouring powder in the kitchen sink, followed by a thorough rinse. This removes any incidental surface coating that could be present during manufacturing. This brings the belt to a known, repeatable, clean condition.  A jig helps to precisely overlay the ends of the belt; note that the two black marks must overlay exactly, or the belt length will be wrong. The dry belt is looped around (above and below) the jig. The splice is glued with vinyl cement. Any bubbles are rolled out with a wallpaper seam roller. The whole seam remains in a press (not shown) overnight.

The bond proved to be quite robust.

html 4/2015