[Vertical walls are very slanted]

Thanks to all. I got it solved because of this forum. It was a friction issue in the x-drive, like gr5's problem but with a different reason. My x rod drive pulley was mounted 1/2 mm to far down the shaft. Since the pulley rides on the race of the rod bearing, this allowed more of the rod to protrude from the bearing and rub on the end plate. Moving the pulley slightly took care of it.

Thinking the slant over, it's surprising how infrequent I was missing steps. An 11 degree angle is 0.2 radians meaning I was missing a single additional step in the +x direction every 5 layers to make the pattern skew to the negative x.

 

[Vertical walls are very slanted]

This is my first time in the forum. The advice is great. The "missing servo steps" explains why the angle gets steeper for parts longer in the x-direction. I don't see any belts rubbing but I can certainly track down the problem now. Thanks all.

 

[Vertical walls are very slanted]

Thanks for the ideas. I've checked them out.

The pulleys are very tight. I can't find slip anywhere in them. The head moves easily, and with the same amount of force in both the x and y directions and over the whole bed. The amount of slant is constant and seems to keep going (tallest part I've made is 2 inches so at 11 degrees, that's a 0.4 inch offset at the top. It seems there must be some slip somewhere to keep accumulating but it's only in one direction and on one axis and very consistent, meaning straight sides are very straight but slanted.

Obviously I'm stumped.

 

[Vertical walls are very slanted]

I'm brand new to Ultimaker. On all my prints, vertical surfaces slant significantly (11 degrees) towards the negative x direction as they build up. In the y direction, they are nice and vertical. Any clues on what's wrong?