Top Layer lines where nozzle restarts

Bambu Lab P1 Series Troubleshooting
1

Hi Guys, I’m trying to print a flat sign that is using Petg material. I would like to avoid ironing. I have tried all the suggestions mentioned in this forum which are …

  • Disabled “Only one wall on top”
  • Switched to Monolithic Top surface
  • Unchecked “Reduce Infill Retraction”
  • Using Top Layer 4 and 5
  • I tried printing from 255F all the way up to 270F.

All the slight blemishes are gone except for the Line that looks to me where the nozzle continues to print after finishing up another area. I don’t know what else to do to get rid of this. I have a Prusa and never had this problem.

I have calibrated the printer and created a separate profile. This is on a P1S printer.

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2

I believe this is tied with the speed of printing of each section of the top surface that impacts the “shine” of the filament, as it varies depending on which filament you use as well

Usually when I’m looking for a really clean top layer I’ll use ironing, i would recommend doing a few tests with small test objects and playing the settings for that specific filament to get the cleanest result possible

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3

Thanks, I’d like to avoid ironing for now as I need it to print fast. Also my farm has some prusa and it prints with no ironing fine. If I mix ironing from my bambu printer the prints won’t look the same.

Do you think lowering down the speed for top layer would fix it ? I will try that next.

4

yeah give it a try, the results should improve with the most constant speed possible, what it does here is that it moves slower on the longer sections and then speeds up on the short parts of the “x” if you are able to have a constant speed on the long and short sections the results will definitely be better, especially with non-matte filaments

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5

I will give it a shot, I will drop top layer speed from 150 to 100, also I will lower fan speeds and see if temp has anything to do with it. Thanks again.

6

If your part doesn’t have to be airtight or watertight, make it under-extrusion a bit, so the top surface would be better. Like, flow from 0.95 down to 0.92 for example. This is to make each strand of filament doesn’t overlapping the neighbors

This is the part I’ve just printed. PTEG, flow ratio 0.9

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Zoooooooom in

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You can see the gap between strands. Just ignore the bubble there since the filament is a bit wet.

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ah!, thats a great idea. I will try that. I think mine is at .99 as I did a calibration and it bumped it up from .95. I can try .90 then and see. Will update as soon as I got the test completed. Thanks!

8

There is a one-click lazy-man’s solution. Turn on ironing.

This photo is not an optical illusion, it is real. The left hand side is basic default print. I only changed the number of top and bottom layers=1 to really exaggerate the layer lines. The right hand side has a modifier applied to it with ironing turn on.

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To further handicap this model, I set the filament profile to Bambu Basic even though this was Jayo PLA. That gave this an uncalibrated filament profile giving it all the disadvantages possible. Feel free to test this with your filament to compare results.

ZTest part.3mf (80.2 KB)

Nothing comes free

So you may be wondering: why isn’t ironing turned on by default?

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Here’s the answer as to what you give up–Time to print:

With Ironing on the right side-only.
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Without Ironing.

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For this 3mm high example, that’s almost a 100% increase in printing time.

Now, having said that, ironing doesn’t solve all problems, but it is a one-click solution to most surface line issues. You can also experiment with the pattern. For example, ironing with a circular pattern can give a molded-like appearance to a symmetrical object.

However, with an asymmetrical object, this can result in patterns that may not be as appealing. On the other hand, with two- or three-color filaments, you can sometimes create unique and interesting patterns.

In the end, my personal preference is to calibrate the filament by hand. I’ll admit, this process is as much art and skill as it is science. You’ll need to decide your own level of commitment to mastering it, but the reward is that, with mastery, nearly any filament can be made to look perfect—or almost perfect. :wink: Some filaments, however, resist calibration; those I return to Amazon for a full refund with freight on their dime, even if I’ve used 25% of the spool trying to calibrate.

3 Likes
9

Just wanted to post an update and the fix. I have tried lowering the top layer speeds and increasing the temp, I also tried lowering fan speeds to have more heat and this didn’t fix the problem. What fixed it for me was lowering flow rate, the default was at .95, after calibration I had it at .99. I lowered it to .90 and it was still visible but then dropped it down to .88 and the lines were gone. Thanks again for your help guys!. The lighting doesn’t do it justice :slight_smile:
465165300_10161211938764724_1163616643953601151_n

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10

looks great, i might start doing that myself instead of resorting to ironing when i want a clean top :slight_smile:

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11

Thanks for closing the loop. There results speak for themselves, that’s a great looking print. I think you’d agree, there is great satisfaction in figuring out the challenge and not allowing the machine to beat you. To paraphrase a famous Colonel in a certain movie “What you smell is like napalm in the morning… the smell of Victory!!!”. :clap:

In the end, it seems like the solution was rooted in manually overriding the calibration. Who would have thunk it??? :yum: It’s at this point that our friend @johnfcooley should bring in his horse. :joy:

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12

Anything for you @Olias :slight_smile:

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13

Lol!, thanks guys, yeah the ironing will mask the imperfection but I strongly believe that the flow rate is what fixed the problem for me. I think changing pattern will also fix it, but will only mask it as it won’t reconnect lines. So yeah I think flow rate is the “actual” problem/solution in this case.

14

I’m having this issue also on literally any size part I print in the Bambu PETG-Transparent from small 3” stuff to this bigger lamp shade I just finished. My A1 is only a week old, I’m brand new to 3D printing.

Spool was dried prior as instructed; it’s not moisture. In my mind, I expected that using Bambu’s own filament would be best suited with the profiles they provide and that they’d be optimized to avoid these sorts of issues, but doesn’t seem to be the case, huh?

15

Welcome to the forum :slight_smile:

Being new to 3D printing, you may want to focus on PLA until you are more comfortable with slicer settings.
PETG is more challenging to print as it likes to cling to the nozzle and is prone to warping. Also, settings for PLA are reasonably straightforward as it is much more forgiving than PETG.

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16

Thanks, Eno.

I did some initial prints in PLA, but for the parts I’m printing functionally I need them to be as transparent as possible which requires the PETG.

I’m an engineer for a living and incredibly mechanically inclined; I’ve spent many, many hours learning before I even bought the machine, even as far as controlling the ambient room temp.

First question is, what’s the point of Bambu filament profiles if they need to be tweaked? Why would they supply their own filament for their own machines with profiles that produce less than optimal results using their own slicer when all other variables are in check?

Second, if using the default profile, what would you recommend to eliminate the banding?

17

Well, the ways of Bambu can be mysterious. So I have found it best to not be angry (at what “should”) and just be surprised (but soldier on).

Printing transparent will not result in perfect transparency as there are physical limitations. It is a layered process without the ability to apply pressure after all. You will not be able to completely eliminate the layer lines.

What needs to be kept in mind is that PETG likes to stick to anything (including the nozzle) and is prone to warping.

To give more detailed advice, it would be helpful to understand what you intend to achieve. Pictures of the unsatisfactory prints
, screenshots of your slicer settings (Filament, Quality, Strength and Speed) and a screenshot of your Flow and Speed preview.

18

Haha, understood, I guess I just don’t see the point of profiles given this information lol.

Understood on the transparency as well; had learned that in my early research, but I’m working out a case for a product I intend to sell in which I’m paying homage to the old Nintendo N64 semi-transparent consoles in which case the PETG-trans is perfect thus far, beyond the banding and I don’t have any warping issues. TBH, this case is 2 halves which snap together and the PLA warped whereas the PTEG didn’t (also using the default Bambu profile for their PLA).

I’ve been trying to post photos since my first reply but I think because my account is new, it’s limiting what I’m allowed to do.

19

Ok so it kept giving me an error trying to post photos from my iPhone, but seems to be working now on my Mac.

This is the lamp shade I printed, you can see the banding on the top.

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This was printed directly from the Bambu Handy App using the settings as provided except for changing to the Bambu PETG trans filament profile.

20

OK, so I think you may be able to do much better with the lampshade. Not so sure about more complex shapes, but the lamp shades looks like it is fitted together from 6 pieces lying flat on the build plate.

When you print from the handy app but change the filament, it will just use the filament defaults, no matter if they are good or bad for what you want to achieve and better transparency is a bit special. You will definetly want to get used to Bambu Studio and/or Orca when printing transparent.

There are a few threads, but I think the most interesting one for you may be this one:

What I would suggest for the lampshade (if it is indeed just flat on the build plate) is:
In the Filament settings: set the bed temps to just below the softening temp, nozzle temp throughout close to the max temp of the filament, enable “wipe while retracting” in the setting overrides, maybe even reduce/cut cooling.
In Quality:
Use a very high layer height, set all line widths to the same width/larger than the nozzle diameter (PETG does not like too large widths, but flat transparency is a special case)
In Strength:
Set walls to 999 in order to eliminate alternating infill patterns.
In Speed:
Reduce all printing speeds to below 100

Note however that while I do hope that this helps with the lampshade, these settings will result in very bad bridging and overhang performance.
But first you need to decide if you can achieve the kind of transparency you want to get. It is quite possible that expectations just can not be met with the current level of tech. But that depends as much on the tech as it does on the expectation.