I'm getting wavy lines on the first layer only in both the x and y direction identically. The first layer is 0.4 mm with a 0.4 mm tip. The other layers are 0.2 mm. I've tried changing the Z offset all the way from -1.2 to 0.5 mm. I've tried changing the hot end leveling the heated bed. None of these changes affected the wavy lines. The waves have about a 1 mm period. The printer is a German RipRap. The material is ABS. The heated bed is 110 °C. I've tried the hot end at 220 °C and 240 °C. So far, nothing has changed the waves.