A minor niggle with the Tigrox crowd control barrier has been the tendency of the film to stick in the slot as it is retracted. We have found that this is helped by changing the profile of the slot and widening the slot. This slot is formed by a 500mm x 5mm insert let into the cavity of this portion of the tool.  This insert was wire eroded by AMEDM in Smethwick, and we then used local Weymouth grinding company Samways Precison to grind the sides of the insert precisely  http://samwaysprecision.co.uk/, as they have a surface grinder capable of grinding to  this length and accuracy.
