whttnbrg wrote:I center a file to the bed, and it starts printing. Everything prints with each layer shifting towards the x home, till it bumps. once it hits the sensor, it starts building straight. what is causing this? once it homes on the X axis, it continues from that point and builds everything just fine.
That IS weird!
Question: Do you G28 before a print starts, to home all axes?
First thing I'd check is the belt tension on the X axis. Loose belts and all that.
Then, I'd double-check/preventatively replace the X end stop switch and wire. The end stop switch acting up can cause weird behavior during a print, including this.
I'd also check to make sure that my extruder wires aren't binding on something early on that lets them get popped back into position when the printer 'rehomes' itself.
Further Question: Do you have a fan cooling your X axis motor? The stock NEMA 14 motor overheats badly on its own, and can/will miss steps when hot. This gets exacerbated with age.