thereafter is the minimum of the function curve calculated for each quality number a few meters of sliver are delivered the quality characterizing magnitude cv value is determined between the delivery roll and the location of sliver deposition output as well as the measuring device 9 at the draw unit input 3 the test run is performed during the charging of one coiler can between the four application points of regulation r reference locations the draw frame is stopped the defined four application points of regulation r have different distances from one another the automatic optimization according to the invention of the application point of regulation has among others the following advantages cv values for the optimization are no longer distorted by effects such as coiler can deposition climatic influences and the like in this manner a better optimization result is achieved effective utilization of the machine control system computer 26 by means of the automatic optimization the optimum application point of regulation may be found even if the data of the working memory and the data of the mechanical setting do not agree with one another and knowledge transfer for performing at the manual optimization to the utilizer operator is dispensed with by virtue of the automatic determination of the application point of regulation principal drafting point not only the sliver uniformity but also to the same extent the cv values of the yarn quality may be improved this was found in wool spinning products and pes bw mixtures the invention was explained in connection with a regulated draw frame 1 it is to be understood that it may find application in other machines which include a regulated draw unit 2 such as a carding machine a combing machine and the like it will be understood that.