A fixture for indexing a work piece, a machine spindle, or the like permits indexing a single rotation of the work piece or other mechanism in any integral number of equal divisions. Stops for the divisions are made to suit the job by assembling a standard roller chain with as many pins and pin spaces as there are to be divisions and mounting the chain about a tapered body, preferably a cone. Fixtures hold the chain at the plane in which the periphery of the cone is the right diameter to receive the chain and other parts adjust the indexing stop to overlie the roller chain at that plane. Adjustments are provided to adjust the indexing stop peripherally of the cone a short distance in order to bring the indexing stop to the required rotational position. This adjustment may also be used to adjust the rotatable part a fraction of an indexing stop.