What could cause this anomaly?

[HienoKaveri 0]

 

Hi,

 

I'm pretty new to printing. I have an Ender 5 Pro with BLtouch, and ran into this issue while printing. Using eSun PLA+, 210C, 65C bed, 0.2layer, speed 60mm/s.

 

There is this strange layer that appears randomly, as seen in the pictures. If I print again with same settings, result can be perfect. Also no telling where and when this happens.

 

The red object is not solid, walls are a few mm thick. Same thing on the gray box, some layers are ruined all of a sudden, then it gets back to normal.

 

I'm sure someone has seen this type of behavior before? What's the deal?

 

thanks.

HK

[GregValiant 1,251]

On the red piece I see that at around layer 15 there was a slight problem, at the visible defect the problem was major, and above the major problem there is another layer that shows the minor defect again.

Since they don't appear to be at regular intervals (Z binding or junk on the Z wheels or something else mechanical) then it would appear that something is intermittently affecting the extrusion.  The Enders (I have a 3 Pro) and CR-10's share the same model hot ends and it's often a partial clog at the bottom of the bowden tube where it is supposed to provide a seal against the top of the nozzle.  If a gap develops there (and it will over time) then longish retractions can pull molten material into the gap between the tube and the nozzle end.  That material in the gap can cause a partial blockage resultant in intermittent flow.

Fixing the problem requires warming up the hot end, taking the nozzle off, pulling out the bowden tube, passing a piece of correctly sized wire (I found a coat hanger that worked) through the hot end to push out the plug of plastic, and trimming off 5 or 6mm of the bowden tube.  The cut on the end of the bowden tube needs to be as exactly square as you can make it.   When re-assembling the hot end - leave the nozzle loose by 1/2 turn, shove the bowden tube back in down to the nozzle, put the lock clip on the tube fitting, and then do a final tighten on the nozzle.  The hot end needs to be hot during that.

The problem could also be a fluctuation in the temperature, but that doesn't happen very often.

If you have a stock Creality extruder that is constructed of plastic then pull the pressure arm off and look at it's bottom side.  Those arms WILL crack and fail at some point.  The fix for that is an aluminum extruder.

[HienoKaveri 0]

*sigh*

Glad it was this simple..