Since I used my UM2 for the first time I always had the problem, that the bed started to oscillate. Mainly on large prints with long straight runs. Some print could be recovered If I got it in time and turn the speed way down (50-60%). But a lot of prints where lost :( Finally I got around to test an idea I had for a long time. I drilled holes in the aluminum plate and cut threads in the holes. Then I screwed some aluminum U-profiles I had laying around to stiffen the bed. The U-profiles shoul