controlling tracking as shown in detail in fig3 and 4 the profiles p enter the spiral grooves 20 of the guide section 19 and are guided by the grooves through the sheet turn about the bar 18 the guide section enables the sheet material to effectively change its direction of movement a slight turn adjustment of the stationary bar 18 shifts the groove track line of the guide section 19 to different positions if necessary should the profile location vary among different sheet spools the turned sheet is conducted over further guide rolls 13 and doubles back over the turnover section 17 to around the shaping shoulder 12 with reference to fig5 the shaping shoulder 12 is configured as that depicted in u s pat no 4 355 494 a spring loaded guide plate device 21 is mounted at the lead side outer surface of the shoulder 12 for channeling one or both of the fastener profile strips p through a groove the spring loading in the guide plate device 21 is preferably adjustable by means of screws 21a to control and maintain tension on the sheet material s the sheet material is passed around the shaping shoulder and then downwardly inside the.