Banding caused by differences in layer time

[nicholasivorjohn]

I’ve noticed that I get slight banding when printing on the X1C when the layer times between layers are significantly different.

I mainly print PLA+ from Sunlu in black colour.

Initially I thought it was the difference in speed that caused this, but upon removing the option to slow down for the layer made it worse. Slowing down the print turns matte zones very shiny and is undesirable.

But when looking in the slicer the bands on the print perfectly correspond to the banding shown in the slicer preview for layer time.

For my particular filament and after many tests I came to the conclusion that any layer that took less than 15 seconds would have visible banding compared to layers that took longer.

So I tried tweaking my print settings for those faster layers to make the layer print a bit slower. I decreased the infill print speed so that it was essentially crawling along, and this helped massively. Were I tweaked these settings the banding went away completely.

I also found that tweaking the speed can help as long as you dont go to slow. Anything slower than 150mm/s and the prints become shiny again.

So with a combination of the 2 you can eliminate the banding but my oh my is it a manual process.

It would be much better if in the layer change section if we could say “if layer_time < 15 seconds then dwell for 15 - layer_time then print a prime tower” but sadly the layer_time parameter doesnt exist or at least is not accessible to us.

Something similar to this exists in Cura where it can move away from the print. This can cause oozing but this can be dealt with by using a prime tower which would only take a few grams of filament.

For those interested here are my settings:

Temp: 220
Part fan cooling: 100%
Aux Fan: 70%
Filament: Sunlu PLA+ Black
Dont slow down for minimum layer time

Default X1C print settings

Ive opened an issue on github: Move away from Print when Layer time is less than X · Issue #2126 · bambulab/BambuStudio · GitHub

If anyone has any other ideas how to mitigate this please share them.

[lkraus]

The filament cooling settings do allow setting a minimum time per layer. I’ve not had your problem or had a need to change the default settings, but it might slow down your print without needing to change individual speed settings.

[nicholasivorjohn]

This slows down the print though, and slowing down the print below a certain amount has undesirable effects. When you slow the print it becomes more shiny, thus compounding this issue.

[Sapper4484]

Glad I found your post. I’ve just got an X1C and very pleased until i came across the same issue for a specific print, it was by chance I was looking through the various options in the slicer and saw the layer time looking exactly like the bands i could see on the print t. I’m printing a Bambu Silver cylinder with some detail on the inside that causes regular slow downs of the layer and in my case its not just visual there are minor differences in the diameter. e.g. fingernail test. Which having been down the rabbit hole I surmise this could be due to minor differences in shrinkage. Testing has shown the same issue on the same part but less obvious with a Matt Bambu filament. My first search led me here and i see there has been a lot of conversation on github which i will follow from now on and. Ill be trying some of the suggestions to see if i can reduce the effect. Its for a model so im not that bothered if i cant get it perfect but i like to understand why things happen for future prints.

[jaysdw]

any updates with a fix on this?

[mgtarallo]

Hi Guys any updates on this - I have a similar issue - posted here:

Different sheen lines on my outer walls - matte / shine WTH?!

Hello Community - I’m trying to identify an issue with these inconsistent glossy versus matte finish sheens visible as Lines on the outer walls. I reduced my cooling down to 50% and turned off the parts fan and raised the filament temperature to 220 with Black Overture PLA filament to achieve a higher sheen like I would get on my Prusa MK3S - and for the most part this has worked but I’m getting these lines along the outer walls in odd places that are not consistent or uniform and they are diffe…

[matulekpl]

this is not same issue. Yours is because of outer wall speed. and ours is about layer time.

I have same situation here:

[metamorph22]

Did you ever get this issue fixed?

[metamorph22]

did you ever get this issue fixed?

[user_3026326371]

There is not real fix for this and some related issues, it just physics…

No matter how fancy our slicers get they still can’t change that we need to heat our filament in order to print it.
The plastic not only needs a certain temp when coming out of the nozzle it also has to hold OR NOT hold a certain temp on the previous layer(s) printed.
For example, PLA does not care much about anything while ABS loves to warp and give you headaches if the model is not hot or cold enough…

The time required to print a layer affects the layer temperature.
Small things need less time per layer than large things.
Most slicers compensate by slowing down the print speeds to allow for more cooling but offer no option to keep AN EVER layer time throughout a model.
Not that it would help much as it just reverses the problem.
Different overall temps for a layer affect by how much it can be flattened with the next layer, the adhesion and for many filaments the look.
In the worst case it results in dimensions or visual changes…

What is the cause of the issues here?
If we leave out the temp of the model than we can focus on our hotend.
Slower speed usually means lower flow rate.
Problem is that the slicer won’t compensate by changing the nozzle temperature
The filament takes on heat energy while going through the hotend.
But we can only optimise this temp for a specific speed.
For more than that we have to define different temps for layers in the slicer.
Not all slicers allow for this, at least not in easy ways based on layer times or such.
Ideally the filament reaches the print temperature with consistency.
Meaning the flow rate would be CONSTANT.
But as far as I know there is no slicer out there providing a feature to print based on keeping the flow rate and nozzle pressure even at all (possible) times…
If you ever created you own candle by dipping a wick into wax you know how vital the consistency of parameters is …

Is there a WORKING workaround until our slicers are able to eliminate these hassles for good ?
Not really, at least not without a lot of manual labour
The only thing I found able to reduce the bad effects a bit is like this:
Accept a much lower than default print speed in order to being able to print all layers, infill and such at the same speed.
Of course this does not work well unless you have a model ideally suited for this and enough time…
If it is mostly the outer layers for single models it MIGHT help to print the outermost wall loop first, rather than the usual inner first.
Be aware of overhangs and such !

In the past, with other printers and those I built myself I used the waste and wait method if a not too large model had to come out ‘perfect’…
Means I added a custom made waste model resulting the overall layer time being more or less equal throughout the model.
For very small area layers I also often included a pause on the waste model (in the infill area) in order to make sure things won’t end up in a wobbling blob of half molten plastic.
Bambu does not make this easy, at least not in ways I am ware of…

[DruiD]

Following this as well as I have signifcant issues with the layer time as well, its easily shown in these “string art” examples.

Interestingly, the problem is strongly observerd and FELT signifcant plastic exposed on the LEFT side closest to the Aux Fan, with the back and front exhibiting some of it , with the right side being far better, layers are visible, but not “felt”.

Left side example -

Right side of same print -

Layer time slicer pic

So I built just a solid cyclindar, liek 5% infill etc, with Left, Right, Back, Front etc at different heights - it didnt do it.
Ignore the mild matte banding and photo quality stuff. this was a fast test print but clealry doesnt have the layer issue.

Another string art with the visbile and producting felt plastic lines - this back of the “C” is the Left side again

Bottom side - you can see it transitioning strongy from LEFT (top corner of Pic) about where my thumb is, toward the RIGHT (bottom of pic) showing these lines\bands almost gone.

‘Right’ Side - barly visible again like the “Right” of the heart.

Any tips on this, I have tried, flow, cooling, slowing, its layer time and obviouisly very prevelant on something that changes layer times like this.

Has anyone logged a support ticket? Any updates from that?

DruiD

[Thermal_Runaway]

I don’t think you will get much from a support ticket because this isn’t an issue with BL printers, it’s an issue with all FDM printers and really more of a software limitation than anything.

You can achieve different surface finishes, and based on my own findings, it’s very effective to take feed rate and travel speed as a function of “surface roughness”. I have that in quotes because I’m not actually measuring roughness, and this is all very unscientific.

I printed a bunch of 200x200mm 1 layer thick sheets of PLA to understand this better myself. By adjusting acceleration magnitude and feed rate (aka print speed), I’m able to print any texture I want just by adjusting speed many times during a print. The glossy textures are those printed at approx. 30 mm/s and the matte or rough surfaces are those printed at ~120-130 mm/s

Also I think this would interest you also. It uses the same concept. The only problem is we don’t have anything like this implemented in our slicer now.

Velocity Painting - Repetier Software

[ioannis]

Not sure whether the issue is with layer time or due to varying speeds. In orca I’ve built a feature to allow the external perimeter to be printed at the same speed regardless of layer time - the inside layers slow down a bit more to compensate. This fixes the shine uniformity issue but I’m not sure whether this addresses the banding issue seen here.

I’d welcome some tests on this as you’re suffering this issue more than I can observe in my prints. The feature is available in the current release (2.1.1) and it’s in the filament settings - cooling, if anyone cares to offer any feedback.

Ps. For the best outer wall consistency print with inner outer inner mode.

[DruiD]

@Thermal_Runaway Not sure if you were replying to OP or my issue or just general.
My issue isnt the layers\banding due to print speed thou, though I admit it may not be the OPs.

Mine is the fac its not consisent one side to the other, irrespective of the model rotation or print speeeds.
Lowering the speed to super low speed just hides the issue - so techniccally yes its related to speed, but a inbalance on one side or the other or miss-calibration etc as at even high speed - one “side” is still smooth-- no banding issues.

[nakleh]

That would be “Don’t slow down for outer walls”, correct?

I wasn’t aware the inner layers were slowed down to compensate, that’s pretty cool. Gonna check that out!

[ioannis]

Yeap that’s right

[user_2149169283]

I have found this happens because of the internal layer construction. That is, if the internal structure is not consistent up the Z axis you get this effect. In my case it was a box with a protrusion on one side, flush to the side in the Z direction. I get a band at the bottom of that protrusion which is caused by the finishing layers of the top of the box meaning the outer skin sticks out a bit more.