**** UPDATE: To make a long thread short, even though the values had been working for some time, it turns out the Y Axis voltage really does need to fall between .5 and .6 The values of .25 to .3 had been working in this printer and has been working in others. Its still a mystery as to why now it became an issue. The positive of this adventure is I have new and better bearings in place and my XY assembly has never been better calibrated. Thanks again for all the support. **** So I have successfully printed several things now, and now I am trying to print the 1.1 parts. To make a long story short the last couple time I have tried that holds the hotends the Y axis has started to drift about the same point in the print. To answer the question yes, I have check all of the screws and belts its all tight, I used blue loctite with all the grub screws too when I assembled it. The drift was in x too on one of the prints. What I am wondering is if this could be the steppers over heating or something else. It could be coincidence but it seems like the drift happened at almost the same layer the last two times I tried the print. One more thing to note, I am starting to hear what I can only describe as a creaking or grinding from the left side of the printer as the Y approach the front of the machine, the sound is there if I move the Y axis by hand as well, I tried loosening the Y axis mount thinking it was binding or stressing the acrylic but that doesn't seem to be the case, could this be the sign of a bad bearing? I am using white lithium grease on the rods. The creaking sound has only developed in the last week or two I believe, when I assembled the Bigbox everything ran smoothly and silently. Could it be possible that the bearing is catching after warming up or something 1/4 of the way through the print?