Rhythmic vertical wide banding  

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richard.s46
(@richard-s46)
Trusted Member

I have read a bunch on the web, and am still looking/reading, but I wanted to post my problem here as well in the hopes someone can directly me quickly to a resolution.  I am printing some tall thin wall (3 layers thick) objects that are exhibiting rhythmic/semi-rhythymic wide banding.  I dont see it in the slice preview where I do see other similar subtle details, so I dont think it is the file.  It seems like it could be changing the amount of extrusion (maybe due to extrusion temp changes?).  Or maybe a fan is turning on and cooling differently for awhile?

If you have any suggestions, please help!

 

    

 

Thanks,

 

Ben

Posted : 26/05/2020 2:04 pm
richard.s46
(@richard-s46)
Trusted Member

The banding is tied to a cutout in the sidewall.  Could this be to a reversal in the direction the filament is being extruded?

 

Posted : 26/05/2020 2:11 pm
richard.s46
(@richard-s46)
Trusted Member

The strange thing is that the banding seems to be limited to one side of the part, starting and stopping at symmetric bulges on each side, though staying synched up with the oval slots.  The area directly around the oval slots does not exhibit the banding, only once past the bulges.

I am trying to print the next very similar part with stealth mode disables to see if it makes any difference.  I can find no defect in the file.

Posted : 26/05/2020 6:49 pm
richard.s46
(@richard-s46)
Trusted Member

No one with any ideas?  Normal mode did not help.  I'mm doing another print right now that has banding that is just plain random, no link to a feature on the part. 

Something must be loose or worn or I dont know what.  It is real annoying though...

Posted : 28/05/2020 1:06 am
Kevin Reid
(@kpreid)
Eminent Member

"Loose or worn" does seem like what's going on with that much visible difference. I don't have any suggestions for you besides "tighten things and shake things".

It looks like there's bigger unwanted-features on the X-aligned surfaces, so that would suggest the problem might be in Y. Check your Y belt tension and make sure the Y pulley set screw is tight and aligned with the motor shaft flat?

Posted : 28/05/2020 1:45 am
Marty
(@mrschultz02)
Eminent Member

That is a tough one, if something was lose you would expect the banding to be near the cut outs, not on the opposite side...  And it seems to return to normal when it passes the cut outs. 

Since it's a thin walled object, time per layer comes to mind, the layers with the cutouts don't take as much time so the layers are not cooling as much.  Those holes are not that big so it's hard to imagine they are changing the layer time that much, but you could try dropping the temperature a few degrees and/or increase fan speed if it's not at 100% already, and see if that helps.

Posted : 28/05/2020 6:51 am
richard.s46
(@richard-s46)
Trusted Member

OK....I may be stupid, but maybe not.....jury is still out.

I was running overdrive at 150%.....usually not a problem, but usually my parts are not so big.  I am currently printing a similar sized part at stock 100% speed.....I bet banding is gone.  A smaller part that I just ran at 100% had no banding.....I hate when I'm stupid.

Posted : 28/05/2020 1:47 pm
richard.s46
(@richard-s46)
Trusted Member

Well, no luck.  Still banding even at 100% normal speed.  I'll keep hunting...

Posted : 29/05/2020 2:09 am
bobstro
(@bobstro)
Illustrious Member
  1. Slow down, particularly external perimeter speeds. I use 25mm/s.
  2. Calibrate extrusion multiplier for that filament.
  3. Add external perimeter if wall is thick enough.
  4. Adjust wall thickness if the part is your design.

Slowing down is always a good 1st troubleshooting steps. If slowing to 50% or below helps, that will identify a range of settings you can test. 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 29/05/2020 2:42 pm
richard.s46
(@richard-s46)
Trusted Member

Thanks, will try speed reduction.  I also have not calibrated filament....lazy.   I do use prusament though, so that's good.

Posted : 30/05/2020 12:17 am
bobstro
(@bobstro)
Illustrious Member
Posted by: @richard-s46

Thanks, will try speed reduction.  I also have not calibrated filament....lazy.   I do use prusament though, so that's good.

Prusament calibration should be spot-on, but do check to account for any printer variations. After filament calibration, I find external perimeter speeds to have the biggest impact on surface finish.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 30/05/2020 3:13 am
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