Patent ID: 8580178

Claim:
A method of forming a strip of heat deformable fabric material for use in a covering for an architectural opening, the method comprising: heating the strip of heat deformable fabric material into a deformable condition; passing the strip of heat deformable fabric material in the deformable condition over an arcuate surface to form the strip of heat deformable fabric material into a transverse arcuate cross section; cooling the strip of heat deformable fabric material to set the transverse arcuate cross section of the strip of heat deformable fabric material; and detecting a tension in the strip of heat deformable fabric material, wherein: the strip of heat deformable fabric material is heated by passing the strip of heat deformable fabric material through a heating chamber; and the tension in the strip of heat deformable fabric material is detected upstream of the heating chamber by a first tension detecting device.