Random Repeatable Lines on Entire Layers

[joshbot007 1]

So now that I have my printer almost where I want it I have one more problem to tackel that I just cant figure out. I am getting these random lines on the sides of my prints that are consistent through the entire layer. The ouside wall is usually inwards on these layers almost as if it is printing the model at 99% scale for that layer then back to 100% scale for the next. It is not layer shift as it is a consistant offset inwards or outwards through the entire layer. I thought I had something loose or my Z axis was messed up or I was underextruding on some layers so I went over the whole printer and printed the benchy again just to find it did the exact same thing on the exact same layers!! This means it is repeatable and has me leaning away from a physical issue and more towards something in the way my slicer is set up or the GCode. It also does it on straight vertical models such as the calibration block pictured, therefor ruling out something with doing angled overhangs in the GCode. Does this sound and look like anything anyone has experienced before based off of my description and the pictures? My printer is an Ender 3 Pro and I am using Cura 4.6 

 

Thanks!

[Labern 774]

I have seen this sort of thing before from first z screw or z bearings that were not that good. You can check the bearing by involving them and see if they fall smoothly under there own weight.

 

Could also be nozzle or bed temp fluctuations or perhaps something to do with the feeder. 

 

With pla you can print on cold glass on blue tape or reduced thinly wiped PVA. To check to see if bed temp has an influence. 

Also monitor your nozzle temp. It may need a PID tune of some sort. 

[joshbot007 1]

Just now, Labern said:

I have seen this sort of thing before from first z screw or z bearings that were not that good. You can check the bearing by involving them and see if they fall smoothly under there own weight.

 

Could also be nozzle or bed temp fluctuations or perhaps something to do with the feeder. 

 

With pla you can print on cold glass on blue tape or reduced thinly wiped PVA. To check to see if bed temp has an influence. 

Also monitor your nozzle temp. It may need a PID tune of some sort. 

Thank you for the sugestions but don't you think that the issue being completely repeatable between prints would mostly rule out these solutions? If it was an underextrusion, bearing, or a temperature problem I would expect the odd layers to show up in random spots between prints and not at the exact same layers while looking the exact same (unless the Gcode is messing with these variables at certain points of course and not varation within the machine). Also my Zaxis is super smooth, I can move my gantry to the top and watch is slowly come most of the way down.

 

Oh and I print with ABS, PLA, TPU, PETG, Carbon fiber, and more in a heated and ventalated enclosure. The problem is not material dependent or print heat range dependent. I only started to tackel it now that I have pretty much everything perfect (inlcuding ABS layer adhesion finally 😄)

Edited July 30, 2020 by joshbot007

[Labern 774]

You may think that it would be random but most of the time I have seen these issues it's been at same layer heights. 

Things like bed temps on bang bang mode, a bad ball catching in a bearing race etc. 

I have had a bed fall under it's own weight ok but the bearing on it's own not fall under own weight. 

[joshbot007 1]

Ok cool, I will check out the bearings and temp!