you probably have no waves because it is under tension unlike a pull down that only has the weight of the bar. I have a 120 dalite HP 2.8 model C pull down that I bought used which has a big wrinkle on the left side when hanging. I really lucked out because my setup requires it to be half way between the bottom stop and the next one above. I use a bar attached to a small dumb bell to hold the screen at the correct location. With the screen under tension of roller spring trying to lift the weight there are no wrinkles at all. Most pull up tripods work the same way..