benjy

After several checks I found my one face that was getting inconsistent layers was caused by a lose x belt but more importantly was "racking", this is when one of the bearings on an axis binds occasionally because of misalignment. On my Bcn3d the right hand side of the y axis was slightly forward of the left (used a jig to measure from a perpendicular straight bar, as my frame is a little bit skewed, could have also used a square against linear rails but again I though the skewed frame might throw off my measurements). Ive also seen this on an A8 with smooth rods where one rod or bearing not aligned parallel to the other. similarly on my cr10s I seen this on the twin leadscrews when one was worn more than the other. So on an Ender (stock) I would replace the wheels on the Y axis because its probably one that drags intermittently, its very hard to see the level of wear on the wheel that can cause these things with the naked eye, just a piece of dirt , a crack , an out of round wheel (had those before egg shaped) or even the inner bearings could be shot. When you do replace them be gentle dont over tighten them, I ruined a few by learning the hard way and grinding flats on them. hope this helps someone