Massive failure

Hey all, only 2 days after bumping up my movement speeds I'm getting misalignments half way through my prints. Not all prints. Yesterday it was an offset of about 1/10th inch. Thought it was a slice error so I rotated part 90 degrees and resliced and part printed great. This part (see pic) misaligned a good half inch. Could this be a belt slipping? Belt and tension seem ok. Thanks.

Did you check the slicer code. Might be something in there telling it to print further out than it should.

You already stated the problem and solution. You bumped the speed up too high. Dial it back a little. It is shifting in the Y axis. The Y axis moves the relatively heavy print bed back and forth- it can't keep up with the X axis which only has to move the extruder carriage. Newton's laws apply!

Sometimes when testing speed we do something like test it by printing a square, where all the axes have to do is move to one end then switch on the other axis. That isn't a good way to adjust speed. It's better to do it with a more complicated print that requires the axes to do a lot of jerking back and forth and changing speeds. That's more like real printing conditions.

Or... You can adjust the maximum Y acceleration. Set that down, and maybe you won't get the same missed steps, though it will slow down print head speed at the same time some, because it won't try to accelerate the bed as much.

It's also important ot note that the print bed gets heavier as the printed part gets built.

It is like the_digital_dentist said, with more complex prints the failure occure more.
I had it with the honeycomb infill. Small fast movements.

Thanks guys, in my zeal to keep things lubed I put a drop on my y axis idler bearing, guess what happened. Cleaned everything with alchohol and tightened up y belt and all is good now. Thanks for the input.