Study on Relation of Hole-edge Combination of Eight-square Hand and Indexing

Eight-square hand is a common gemstone processing chucking appliance and the main function is to provide the accurate indexing variation of the gemstone processing.The indexing variation is achieved by the association between hole and edge,which is influenced by the distribution of hole position.In this paper,as an example,the distribution rule of the hole of sixty-four indexing eight-square hand is analyzed by graphic method and tabulation method.The conclusion is that eight holes of eight-square hand are non-symmetric.After comparing the three different relationships of hole-edge combination and indexing,the results show that the indexing variation will be easily achieved through hole-edge combination when the hole distribution is regular and concentrated.Also three formulas of hole-edge combination and indexing are summarized,which will facilitate the gemstone processing and improve labor productivity.