Horizontal Banding Issue  

Re: Horizontal Banding Issue

I'm having this too on a few prints, and the truth is you can never get it away completely.

I don't know where it comes mainly from, but i have a hunch that some of these factors below are more to blame than others.

There are multiple possibilities for this problem:

- Filament diamenter varies every few centimeters. Some filaments show this more than others, like while PLA for example. Take two meters of filament, measure it via a digital caliper every 10cm, if it's not 1.75 +- 0.05 then the filament is bad. I have expensive white filament that shows these values 1.73, 1.68, 1.62, 1.78, 1.82 and so on.
- Cooling. Not cooling fast enough results in the layed down filament doing what it wants, like expanding and hardening in uncontrollable directions. This results in what looks like underextruded and overextruded layer lines. Slow down the print to around 60% or so.
- Pressure put on the filament by the hobbed gear. loosening the screws so that the hobbed gears barely catch the filament and the print still extrudes over many hours will work wonders in reducing this banding.
- The Slicer. SlicerPE is absolutely awesome, but it seems like it has some problems with their slicing engine. Some prints will never look good no matter how you slice them. Switch to Cura for a test (after using this tutorial https://manual.prusa3d.com/Guide/How+to+import+profiles+to+Cura+%28Windows+%26+macOS%29/703 ), and your print will look totally different with the same settings. Cura doesn't always print great, sometimes it does things to the prints where i'm still scratching my head on what the heck went wrong.
- some other things i forgot because i'm sitting in a bar ass drunk right now 😛

Re: Horizontal Banding Issue

I would like to add that this could be caused by the force of pulling the filament off the spool. Are you using the standard Prusa holder that sits above the machine?

As a little test, try pushing down very slightly on your extruder with it positioned in the middle of the X dimension and a bit raised off the bed. Can you notice that it is not very rigid and bends easily? The force required to pull the spool around will cause a deflection of the nozzle and in theory this should raise and lower the nozzle. I don't know the degree of affect this will cause but it could be something to investigate.

You could move the print to the far left side of the machine and see if this works better than printing in the middle (the machine is a little more rigid at the ends).

Or, you could move the filament spool off the machine and off to the side.... or you could man the print in person and keep the filament slack.

A 2nd thought is that the Z axis screws and nuts may be binding and causing some trouble with the Z axis motion. What I have done to check this is to remove the Z axis nuts from the carriage parts (two screws per side) and then notice where the leadscrew 'wants' to be. hopefully the leadscrew will be centered directly in the bore through the plastic parts as you manually move the X axis assembly up and down.

I have also seen an extreme version of this the ONE time I tried to use my Printrbot with the new heated bed retrofit. The banding was so enormous it was almost comical. That printer had a heating element bolted to the bottom of an Aluminum platen and I think what was happening is that the bed would rise up and down each time the heater cycled ON and OFF. The PID tuning must have been truly horrible. That is when I decided to give up on that printer and buy this new one : )