A machine, for example machine for cutting discrete sheets of material from a web, which includes a web supply and a processing station such as a cutoff station, is provided with a variable index drive operating feed structure for moving the web intermittently a predetermined but adjustable distance. The web is advanced intermittently and at which the frequency that varies in direct relation to the continuous speed of an input drive motor. The amount at which the web is fed during each cycle of the intermittent motion is settable by an operator by varying a continuous dial of a variable index drive. The variable index drive is a mechanical transmission having an index mechanism which produces a first intermittent output, a variable ratio unit connected at the output of the index mechanism for producing a second intermittent output having a speed that differs from the direct output of the index mechanism by the setting of the variable ratio unit, and a differential which produces a variable displacement in each cycle by combining the two outputs.