I decided to try Emmett Lalish's tricky Pre-assembled Spherical Iris box ("not for the faint-hearted and needs a well-tuned printer") on both my trusty old Mendel90 and my new E3D BigBox. Taking it slowly, it's a 10-11 hour print at 0.15 mm resolution, so I left it running overnight. The Mendel90 did well although a little over-extruded, meaning I haven't been able to get the mechanism to work yet. The BigBox however, presented me with this mess. No signs of over-extrusion - I think the mechanism would have stood a much better chance of working on this copy - so no real clues as to why there should have been such a sudden and dramatic shift in the Y direction. This is becoming an all too frequent occurrence lately, and I believe the shift is usually parallel to the Y axis. Anybody care to suggest what may be causing this?
First thing to confirm, is the print still attached to the bed? Some have found that they have steppers missing moves, myself included. For me it was on the z-axis. Check and double check your stepper driver voltages. Check your belts are tight and that your pulleys are not slipping.
Thanks, Jason. Print is firmly attached until the bed cools, then it releases completely. Print Bite is far and away the best surface I have ever used! I now have it on both printers. Stepper drivers just rechecked - all five are still reading 0.56 V. Belts are tight and pulleys are rock solid.