approximately 1 8 in away from the edge of the webbing 11 as depicted in fig9 with the spring fingers 210 engaged on the webbing 11 the cylinders 66 70 are actuated to move the clamp fingers 28 back to their retracted position and the cylinders 120 122 are actuated to move the tread carrier 112 upwardly out of contact with the combined webbing and netting structure the motor 104 is then activated to move the progressive linear clamp 18 back to its home position to the left of the folding and clamping station 14 as viewed in fig1 subsequent to the clamping fingers 28 and progressive linear clamp 18 disengaging from the combined webbing and netting structure the feed mechanism 22 is moved along the support rail 24 in the direction of the sewing station 16 as the feed mechanism 22 moves it slides the combined webbing and netting structure longitudinally through the channel 12 a conventional sewing device is provided for sewing the webbing and netting materials together and the belt 214 is preferably actuated to convey the material through the sewing station at a rate which is comparable to the operating rate of the sewing device after the sewing operation.