During a rather intensive period of printing more and more shifts are noticed in the x-direction. At some moment, however, the printer was completely out of control. An investigation show that it was difficult to displace the flat bed in the x-direction. In the first instance it was believed that one of the linear ball bearings was cruched. However, after removing the belt they run too smooth to explane the heavy resistance. It appeared soon that the ball bearing used to stretch the belt was completely broken. All the balls were gone.
Actually I was happy that this was the problem, because this bearing is much easier to replace than the linear bearings.
A lesson learned is that also these bearings have to be checked if the movements are not smooth.
