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Z banding when ever I use infill - what's wrong?

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Recently my UMO+ is showing very periodic Z banding whenever I print with infill. Please help me figure out what has changed and/or what I should try to get smooth prints again. This is a recent development with my printer.

Ultimaker Original Plus, CURA 15.04.2, 14mm diameter test cylinder, ColorFabb PLA/PHA

z-banding1.thumb.JPG.b4c399b6f700c905c145b77a1894b098.JPG

Cylinder on the right:

layer_height = 0.2

wall_thickness = 0.8

retraction_enable = True

solid_layer_thickness = .6

fill_density = 17

print_speed = 40

print_temperature = 190

The cyinder on the left:

layer_height = 0.2

wall_thickness = 0.4

retraction_enable = True

solid_layer_thickness = .6

fill_density = 0

print_speed = 40

print_temperature = 190

z-banding1.thumb.JPG.b4c399b6f700c905c145b77a1894b098.JPG

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Hello,

Did you invert the descriptions of the cylinders? On the right you have no infill and on the left you do.

The z banding seems very constant. It is probably some issue with one of the bearings or something is affecting the z step causing it to not be smooth.

If its not the z step then you would probably have some issue with temperature changing.

You say you are using the UM+. Are you enabling the heated bed for these prints?

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Hi Mark,

Have you tried upping shell thickness to 1.2mm? With thicker shells, infill will show through less, and generally will produce a nicer outer appearance for your model.

It also looks like the model with the infill actually looks better than the one without (unless the model is supposed to have the ridging). Could you post the stl or the gcode for what you're trying to print?

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thanks! for the help.

@pm_dude , i did get the order wrong on the descriptions. I am using the heated bed but only at about 27C to make up for cold room. I am using blue tape for sticking to the bed. The temp seems fine drifting +-3 degrees and mostly when the fan comes on.

@Remy - I tryied 1.2wall and still had some issues. Also see photo of the inside the the 0.8 wall print the banding is on the inside too.

this pic is 0.4 wall, 0.8 wall, 1.2 wall

5a331257e76f0_photo2.thumb.JPG.f98aa8781ecfd21f0acefcac4e313ca7.JPG

5a33125ba4f6d_photo1.thumb.JPG.816f8276ebabc235c7c411f122f7746d.JPG

I am starting to think it might be time or speed related since the band get father appart at the tops of these cone shapes. and the large diameter looks good, these cone shapes were both at 0.8 wall

5a33125841e1c_photo3.thumb.JPG.a627a57764441837bae41e2b4dd77374.JPG

photo.thumb.JPG.760f5dbd6118d48fe90b1347edcb1ca6.JPG

5a331257e76f0_photo2.thumb.JPG.f98aa8781ecfd21f0acefcac4e313ca7.JPG

5a33125ba4f6d_photo1.thumb.JPG.816f8276ebabc235c7c411f122f7746d.JPG

5a33125841e1c_photo3.thumb.JPG.a627a57764441837bae41e2b4dd77374.JPG

photo.thumb.JPG.760f5dbd6118d48fe90b1347edcb1ca6.JPG

Edited by Guest

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update - (still baffled) here's a photo of test prints showing (i think) the periodic banding at certain print speeds. I think am seeing a relationship between the the appearance of banding and print speed. What do you think?

5a33125f3353c_3towers-1.thumb.jpg.3dce667416b4d2b9fb09c40214659360.jpg

The two that were printed at 0.8mm wall are showing pronounced banding on diameters in the range 9mm-5mm while the tower printed at 1.2mm wall is showing banding on the range 7mm-3mm. I'm explaing this shift by the fact that the setting for "Minimal layer time=4seconds" on the 1.2mm wall print would slow down later than the print done at 0.8mm wall so the banding would show up higher.

I did print the basic cylinder on two other UMO+ machines and they look good.

If anyone wants to give is a rip on thier machine I have uploaded the STL files and openSCAD code here.

https://www.youmagine.com/designs/cylinder-tower-test-print-customizable

(edit - applying belt tentioners did not effect this issue, but I have some nice sounding belts now, pling pling)

I'm grapsing at straws now...I'm not sure what to do next. I do think 3 of my 4 x-y blets are a bit looser than the tightest one, maybe I'll print some belt tighteners and see if that changes anything.

5a33125f3353c_3towers-1.thumb.jpg.3dce667416b4d2b9fb09c40214659360.jpg

Edited by Guest

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I hope someone can tell me I'm over thinking this and there is a simpler explaination.

anyway, here's what I have today.

so I'm thinking the zone of around 20mm/sec print speed is the trouble zone for my printer.

Here's photo showing some data also interesing feature that the period of the banding seems to change. I've also included what I calculated the adjusted print speeds to be at each section (based on the 4 second minimum layer speed setting I am using).

cylinder-periods_9to6.thumb.jpg.c38f0f15e68cc13b268acf2a45ae9caa.jpg

SO I tried re-printing one of my early tests at 20mm/s to see if I could make this happen to a previously nice print. here's a photo, same settings just one was at 20mm/s and the original one at 40mm/s. Looks like I can make this happen by printing anything around the 20mm/s speed. Looks like the z-bands period is smaller than a complete revolution since the z scar shows the bands not matching up.

5a33126355a50_bigcylinder-20mm.sand40mm.s.thumb.jpg.3fc550754e2f30af213ae66532170432.jpg

cylinder-periods_9to6.thumb.jpg.c38f0f15e68cc13b268acf2a45ae9caa.jpg

5a33126355a50_bigcylinder-20mm.sand40mm.s.thumb.jpg.3fc550754e2f30af213ae66532170432.jpg

Edited by Guest

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based on the results, i think its the extruder or filament since the banding changes based on layer size. does this seem right? i think i can rule out the z screw and bed assembly.

 

The 40mm/s model you posted looks a lot nicer than the 20mm/s one. What temp are you printing at? For slower speeds you need to use cooler temps, otherwise the plastic will still be hot and malleable when the next layer gets put down. The nozzle can cause the previous layer to bulge out a bit since it has not set yet. The banding is really consistent so this may not be the case here, but nozzle temp could be a factor.

I don't have access to a UMO here but I will try running the cylinder towers on a UM2 later today with varied settings and let you know if I can reproduce the issue.

Unless you have solved it already of course! :)

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What temp are you printing at?

 

I'm printing at 190C which is a good temp for ColorFabb PLA/PHA. I have not figured it out yet. :-( but I did print one of the towers on another UMO+ at work and it came out smooth all the way up (same gcode actually!) So I know it's something with my machine. I have not had more time to trouble shoot but hope to this weekend.

And like you say the banding is so regular and is effected my the layer time that I think it's something about the extuder going at the slow speed.

Edited by Guest

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ok this is still driving me crazy. This weekend I asked folks at my local maker's space for ideas why this is happening only on my machine, the UMO+s I have at work do not do this. They suggested it might be a power supply issues. So I brought home one of the power supplies from work to try on my printer. here's my test prints. I included a print done at work to show how nice those look.

the 7 prints I did at home were all done back to back, from the same gcode file.

Anyone have any ideas for me , this is making me insane! also FYI - I'm convinced this is happening only when printing around 20mm/s

5a33196105925_zridgeson3partcylinder-notes.thumb.jpg.e00fd9522700d0370923b48ce7768b41.jpg

5a33196105925_zridgeson3partcylinder-notes.thumb.jpg.e00fd9522700d0370923b48ce7768b41.jpg

Edited by Guest

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Have you tried bringing an UMO+ from your school to your home, or the other way around to see how that works?

And what is the difference between print 1 and 4?

 

I have not tried moving the printers to different spaces, but out of desperation I can try that.

and #4!! I know what the heck? it's a confounding outlier.

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WOW. Now that's interesting. Also just wondering, if your table or the area where you print it's rock solid or absorbs vibrations?

Ofc there seems to be something else there on the power

 

I would say "adsorbs". It's on an old wooden table on foam cubes (to make it quieter).

the fact that this z-wave seems to be linked to printing speed really has me stumped. Of course I may be latching on to that. So I appreciate other perspectives to help me see other possible correlations and causes.

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This banding can be caused by very few things:

1) A height issues where the bed doesn't move down w;hen it should so you are printing once or twice basically at the same height or maybe the bed doesn't move down as far as it should.

2) Temperature fluctuations - easily detected because you can actually read the temp off the controller while it is printing and it has to be > 5C to see stuff like this and usually it's not so severe.

3) filament fluctuations- also easily detected - for this severe overextrusion you would easily see filament diameter changes.

BY FAR the most likely issue is #1 but this issue can be divided into many sub issues.

Note that the spacing on the UMO threading is 3mm and your pattern also appears to be about 3mm. i recommend you measure this distance both on the Z screw and on your parts. Instead of measuring the distance directly, measure the distance between say 5 threads and divide by 5. Or 5 "bumps" and divide by 5. This way you get a more accurate result.

Anyway your z stage is probably sticking or maybe your Z screw is wobbly. Try moving the bed up and down by hand. Try greasing it. Move it electronically up and down - does it wobble? The higher speed printing creates more violent vibrations which can make the bed stick less. Such that the bed doesn't get stuck at a given height.

Sometimes adding a weight to the bed can help - about 2 pounds is good. Near the back. Alternatively try printing sideways with *less* weight on the bed.

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Thanks for all the great suggestions, it's much appreciated! Here's my results.

(FYI - I had to stop doing test prints tonight and start printing handouts for the sessions I'm presenting at at MACUL Thursday and Friday. It will be Saturday when I can do more test prints)

 

1. I re-greased.

2. moved the bed up and down electrically and did not see skipping like in the video.

3. While the steppers were still energized I tried moving the bed up and down by hand and I think I do detect some small wiggle.

4. added a 40oz (2.5lb) weight to the back and ran two test prints, the 1st one slightly better but the 2nd one was back to it's old tricks. (two separate print runs back to back)

@gr5 the banding seems to be related to the distance printed, see the images above where the period of the banding changes for different diameters. Also see the large diameter print where at the z scar the banding does not "match up". I feel like at a low speeds I end up with periodic under-over extruding where the period has to do with amount extruded. I have measured my filament (colorfabb) and I'm pretty satisfied that it's not varying more than +-0.04mm. I'm worried it might be my extruder.

here's the photos of the 2 prints I did with the weight on the bed.

5a33196f96801_zridges40ozweight-notes.thumb.jpg.23738816005f67a42cc24d499abe4185.jpg

Ok i hesitate to show this photo since I'm not convinced in what I am seeing and have not tested this more...but......here''s another thing I have noticed (which may or may not actually support my suspicion about the extruder) This is a picture of bed leveling print that I run from time to time to check my level and adjust it on the fly. (anyway) what you see is periodic patterns of thin and thick lines. this was done at 20mm/s and may be due to the extruder, or maybe my bed has wavy lines. I have not tried rotating the test pattern by 90 degrees to see if the bed is the cause or if I am really seeing extruder periodic over-under extrusions.

5a33196fd9791_bedlevelbands.thumb.JPG.1748a5da52901a2938015d27aef9f878.JPG

5a33196f96801_zridges40ozweight-notes.thumb.jpg.23738816005f67a42cc24d499abe4185.jpg

5a33196fd9791_bedlevelbands.thumb.JPG.1748a5da52901a2938015d27aef9f878.JPG

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Well I left out #4 on the list above - the extruder speeds up and slows down but I thought that too unlikely to mention. But I have to admit the evidence (different spacing on different diameter cylinders) agrees better with "extruder speed changing".

Is the gear on your extruder not round? The only way it can be the extruder is if it speeds up for a little while and then slows down again. Maybe something is off center?

You have to realize that just measuring the distance that the filament moves (or z axis moves) might be difficult to notice as this problem is a bit subtle (yes it's easy to see on the walls but that could be just 30% over extrusion).

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ok, I finally got back to do some testing and I'm still lost. :(

Not all is lost, I think I have decided printing the 1st layer is not a good way to test my "slow-speed-extrusion-problem" theory, BECAUSE I think my bed is not flat.

here's the most dramatic image, printed at 20mm/sec showing what I think is bed waves. Since the thin to thick sections do not appear periodic with the distance the path travels BUT periodic along the x direction in bands.

zwave-spiral_20mm-lable.thumb.jpg.e3a43ee7e699f922876e8d0438cd3727.jpg

Here's some more test prints I ran at different speeds, thinking I might get no bands at higher speeds but I think was my bed was going down a little every print so each print was a little thicker and I stopped seeing the bed waves.

zwave-spiral1_40mm-lable.thumb.jpg.d89a379d1c59a068089e55c5fb73ff54.jpg

zwave-spiral2_15mm-lable.thumb.jpg.2eadeead76231c5b07b9ffc9118cc6f7.jpg

zwave-spiral3_20mm-lable.thumb.jpg.5a5176e63a0104ead03e2fab0aa2344f.jpg

zwave-spiral4_40mm-lable.thumb.jpg.a45211b16a22148cc8f430890b5d08be.jpg

zwave-spiral5_15mm-lable.thumb.jpg.237d71208dbb9efecf727cc78c538402.jpg

zwave-spiral_20mm-lable.thumb.jpg.e3a43ee7e699f922876e8d0438cd3727.jpg

zwave-spiral1_40mm-lable.thumb.jpg.d89a379d1c59a068089e55c5fb73ff54.jpg

zwave-spiral2_15mm-lable.thumb.jpg.2eadeead76231c5b07b9ffc9118cc6f7.jpg

zwave-spiral3_20mm-lable.thumb.jpg.5a5176e63a0104ead03e2fab0aa2344f.jpg

zwave-spiral4_40mm-lable.thumb.jpg.a45211b16a22148cc8f430890b5d08be.jpg

zwave-spiral5_15mm-lable.thumb.jpg.237d71208dbb9efecf727cc78c538402.jpg

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Look like an eagle when it moves and check if the sideblocks move up/down

giphy.gif

Also, check that the head when you move x/y by hand (fast moves) doesn't do a 'tack tack' sound, because then it might be the linear bearings.

Also if it's an umo+ check this for the bed screws might be pushing the glass

https://ultimaker.com/en/community/10335-glass-plate-not-flat

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thanks for the ideas. Here's me checking my rods.

1st you'll see the block on the Y axis wiggle a tiny amount when moving in the X direction.

Next I move the head a round fast since I'm not sure what "tack tack" sound I'm looking for.

Also I think I see similar but maybe less wiggle on the X blocks when moving in the Y direction. I wonder if this is in the "normal" range, I 'll look at the printers at work to see if they look the same. If this was causing my issue would I still see the apparent correlation to printing speed and my z-waves?

 

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