Banding in GCODE and in print

[BPQ1991 0]

Hello all, I've got a very interesting (read annoying) issue that cropped up in the last day or so. I've sliced a print and sent it to the printer and it prints in these zebra striped bands. When I look at octoprint on a mac i can see the banding on a pc i don't see the banding and on the print ... oh boy do i see the banding. Not sure how to fix this or what details are needed to help out. I've attached some photos and my cura version is: 4.12.1. Any help is good help at this point!!

 

Thanks =D

GA_xshelf_bracket_-25mm pla.gcode

2022-03-28_22-32-47.pdf

[GregValiant 1,358]

The gcode file you posted is different than the one in your photos.

That photo of a print looks like there is an extruder problem.  What printer is that?

[GregValiant 1,358]

I found it.  Geeetech A20M.

To the right of the Settings Search box is an icon with three lines on it.  Click on it and set the visibility to "All".  In the Material Settings check all the flow% numbers.

It looks like the skirt is going down at exactly 90% flow.  That doesn't account for all the banding though.  It looks more like the extruder is stopping and starting or some other problem that is causing intermittent extrusion.

Use the "File | Save Project" command and Cura will save a 3mf file with all your settings and the model.  Post that file here.

 

Edited March 29, 2022 by GregValiant

[BPQ1991 0]

@GregValiant Thank you so much for your quick response!!!! Sorry for the wrong gcode, I've attached the correct one. I also think I may have found the root of the evil. I'm running a test as I post this to validate. Sooo, you mentioned it is leaning towards being an extruder issue. I had my 1.5KG spool of PETG in a filament dryer and I think that may have been putting a little drag on the filament. I took it out of the PTFE tube and looked at it and i noticed some morse code (dots where the extruder pushed the filament through and dashes where the filament was slipping in the extruder gear teeth), I put the filament spool on the stock spool holder and am now running a test with the same gcode on the octaprint server. I've attached the files in question.

 

So .. tension on the extruder wasn't it. Still printing like crap. I am going to disassemble the hot end, put new PTFE tubing in, and also take the extruder apart and clean it as well. I may also change nozzles. I noticed quite a bit of filament dust on the gear. Any tips on the best way to clean the hot end?

 

I've printed a bunch of layers now and it is spotty at best. I am going to abort the print because it is a mount for an xbox and the last thing I want is for it to be weak =D.

 

Again, THANK YOU so much for your help =D You have no idea how much I appreciate it.

GA_xshelf_shelf_final.gcode GA_xshelf_shelf_final.3mf

[GregValiant 1,358]

The numbers in the gcode say extrusion is at 100% flow (if you're Mr. Spock it's 99.9882%)

 

My hot end is a single so it's straight through.  I found a piece of wire that is 1.75mm and (with the bowden and nozzle out) I push it through the warmed up hot end.  It usually gets something out.  In your case I don't know how you would handle the merge area.  I suppose a smaller piece of wire would work.  Maybe something like a broken guitar string.

 

I have a simple system for cleaning nozzles.  I hold it with a piece of pliers and put a propane torch to it.  When the flaming drips stop I drop it into a glass of water and then clean out the inside better with a watchmaker screwdriver and the cleaning needle that came with the printer.  Looking back - I don't think I've ever had a true "plugged nozzle".  It was always a plug that formed at the bottom of the bowden tube.  Printing a lot of PETG will eventually hurt even a Capricorn tube.

 

The grinding of the filament is a definite problem.  Are you confident that the extruder tension arm is adjusted tight enough?  Usually when things get bad and the filament won't push then the extruder skips steps.  If it is turning and not pushing then maybe it's just not gripping the filament tight enough.

[BPQ1991 0]

@GregValiant Ok great tips. I have a propane torch I use to smooth PLA prints I can use to clean the nozzle. I decided to let the print play itself out and print =D. So far it actually doesn't look so bad after the first 3 layers. Im thinking it may be an issue of the layers not sticking to the bed and then catch and collect on the hot end and the nozzle. Either way I'm going to clean everything up and retry the print again tomorrow after this one finishes. I'll send a photo of the print with the "bad/dirty" parts and then again after it has been cleaned.

 

I actually put a Creality CR10s Pro v2 on order from Tiny Machines because of the level of frustration :(. I ordered an all metal hot end and upgraded DDX extruders right off the bat. I don't want to deal with these problems on just about every major print with this printer =D. It's ok for smaller prints but when I want to print PETG and big prints it is a bit of a challenge.

 

Greg, thank you for all your assistance and advice! You've been an enormous help!!

 

 

[BPQ1991 0]

AAAND it failed miserably. As soon as it got to the infill it failed. I'm going to take it apart and clean it well and replace things and see what happens.

 

 

[BPQ1991 0]

I had to post a follow up to this thread to give @GregValiant some serious props. I cleaned the hot end using his suggestions. I used a NEW nozzle rather than cleaning the old one. I also put some filament in the dormant side of the hot end (I have an A20M so 2 into 1 and the merge as was suggested could be an issue). Purged everything with 750mm of filament extruded through EACH extruder and ... man .. what a difference !!

This is one of the best prints this printer has done ... bar none ... since it was new. I learned a couple things. These brass nozzles are disposable so I will be disposing them. The PTFE tubing also degrades pretty quickly. Lastly, I put more meters of filament through this thing than I realized. I am searching for a plugin to octaprint that will track filament though the printer universally. The hot end was filthy ... and once it was cleared up .. BOOOM beautiful prints!

 

Thank you again @GregValiant I really appreaciate the input and guidance. I'm happy and most importantly my prints are coming out excellently.

 

I also did notice that the stock extruder with this A20M the teeth are weak. I can see wear lines in them, so I am shopping for upgraded dual gear extruders for it. If anyone has any suggestions I'm game!!! I am amazed at how much wear plastic can put on metal .... the teeth on tool0 are not in good shape.

 

 

[BPQ1991 0]

Just an update with the final print. Has 3 small defects in the wall but over all ... I cannot complain. It is SUPER strong and the print feels extra solid. After 16 hours I am very very happy with the output. Going to close out this thread now. Thanks again one last time @GregValiant =D you have no idea how happy I am that this print worked!!