Prusa Core One: Serious Layer Shifting but not every time
Hi folks! Just got this Core One, new in box, and it's already having some problems. I'm a bit frustrated as, given the high price tag, I was expecting it to be near perfect.
The biggest issue I'm having is something I can only call "layer shifting" but I don't know if that's actually what it's called. Basically it has an X/Y shift partway through the print, not always at the same point, and then it keeps printing. It doesn't recognize that anything is wrong and goes along happily printing the rest of the model in a new position, often giving me spaghetti. This seems to happen when I print more than one copy of something but I've also seen it happen when printing one object. It also doesn't happen every time so I don't believe that it is an error in the gcode.
I've noticed a few other errors that appear intermittently with the printer. First of all it sometimes boots up and tells me that it "can't find all the puppies"? I have no idea what that means. It also initially had difficulty with doing Z-Axis calibration out of the box but I applied lubrication and manually re-leveled the bed by unscrewing, dropping to bottom, and re-screwing and it seems to not have that issue anymore. I could be wrong but this issue doesn't seem related to the z-axis as it only seems to be shifting in the X/Y axis. There's no floating or digging going on that would lead me to think that it isn't moving up/down properly and the amount of shift seems too significant to be related to bed leveling. Bed adhesion and first layers are consistently still good. The shift always seems to happen part way through the model.
RE:
First run the manual belt calibration and make sure the belts are not too loose. Next, with motors disengaged move the print head by hand to all four corners and make sure nothing is binding or main cable sagging and getting between the printhead and the motor.
Also, layer shifts can happen when a part warps and the print head collides with it.
Rerun X and Y calibration.
RE: Prusa Core One: Serious Layer Shifting but not every time
Hi,
Try my grocery list of fixes here.
Before doing the more esoteric fixes, you might simply try using Classic slicing instead of Arachne and turning off arc fitting.
RE: Prusa Core One: Serious Layer Shifting but not every time
Does the shift always occur in the same axis? In the pictures it appears to be in a line from the front left to the rear right. With a core xy printer the belts drive the extruder front left to rear right and front right to rear left, not front to back and left to right.
If the shift is always along the left front to rear right axis, check the upper belt and the motor in the left rear corner. Make sure the set screws that hold the pulley in place on the motor shaft are not loose.
RE: Prusa Core One: Serious Layer Shifting but not every time
Hi hyiger!
Thank you for your advice. I started by attempting the manual belt calibration using the wizard inside the Prusa Core One menu. I noticed during the frequency tests that the upper belt NEVER resonated at all. Actually what was very weird was that when it was trying to resonate the upper belt it instead resonated the lower one (basically it just was calibrating the lower one twice). What should I loosen if the upper belt is too tight? Or is this a sign that something else might be wrong?
RE: Prusa Core One: Serious Layer Shifting but not every time
Push the extruder all the way to one side and then press each belt towards the linear rail. The tension should feel roughly the same on both belts. If it does the tension on the upper belt isn't stopping the calibration routine from vibrating the belt.
Check the set screws on the left motor pulley. If the screws are loose, the calibration routine isn't going to make the belt vibrate.
One of the screws should tighten on the flat of the motor shaft. You can see this by looking through the right side panel.
RE: Prusa Core One: Serious Layer Shifting but not every time
Hi hyiger!
Thank you for your advice. I started by attempting the manual belt calibration using the wizard inside the Prusa Core One menu. I noticed during the frequency tests that the upper belt NEVER resonated at all. Actually what was very weird was that when it was trying to resonate the upper belt it instead resonated the lower one (basically it just was calibrating the lower one twice). What should I loosen if the upper belt is too tight? Or is this a sign that something else might be wrong?
First run Y calibration. If it passes then run the manual belt calibration. If the upper belts in not oscillating at all across the frequency range, it would mean it's either too tight or too loose. What you can try is in the manual belt tuner set the upper belt frequency to 95hz. Then turn both belt tension screws by the same amount (around 1/4 turn) and in the same direction (you can alternate between them). Do not turn them independently or you can bend the gantry out of alignment. Do this until the belt starts to oscillate.
I suspect maybe your belts are too loose.
Another possibility is that your main cable and PTFE tube could be sagging and getting wedged between the print head and the x-motor.