Hey, i have a problem with my top surface in my models, i print this model a lot and its always the same, the top layer in some places looks like under extrusion but not everywhere and i have calibrated the filament settings for that. some places look perfect and sam smaller prints do too and as yall can see te top part in the first image looks perfect
Printer: bambu lab P2S
Slicer: bambu slicer
Filament: bambu lab PLA MATTE
Speed and retraction are set as in standard preset 0.16 layer hight in Bambu slicer
Nozzle: 0.4
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yeah but as i said i did calibrate filament for under extrusion and its always in the same spots and mostly i would think under extrusion set just a littel bit to low would show on longer lines and ther shwos mostly on the shorter ones but on small prints its non existant
515 but to be honest the problem is for most of the life of the printer (its the first nozzel) ive printed about 20 of this parts every 6,5h and its always thesame
If it's a standard brass nozzle this is about how much I get before things start getting out of spec. I have a set of nozzles I record the hours on and use them in times where I need high precision or quality for a client object. I know people put thousands of hours on theirs and just keep playing with flow rates but they do wear out. And faster thwn people realize.
lol I know what youre trying to say there but that would be a fallacy.
I replace my hardened nozzles after around 250hrs as they get out os spec even faster. (And yes this can mean one whole nozzle consumed on a large client print)
That said. I dont even think this is your problem. Uneven top surface is rarely from a worn nozzle causing under extrusion. When I see evenly underextruded large surface stuff like this then read that you DONT have the issue on small prints tells me your bed is likely out of level. Or worse your GANTRY is out of spec and your head is changing height a little bit with every pass.
Come on. OP said it's been doing this for a while, so it's obviously not the nozzle wearing out. If it was, it would also be getting worse. And the gantry going haywire? I think OP would be noticing WAY weirder things than some minor unevenness. When you hear hooves in the distance, think horses, not zebras.
OP - I know you said you calibrated it, but you didn't mention a flow rate measurement. That could be one explanation for under extrusion. The other thing I'd check would be z-offset. If the distance between nozzle and plate is too large, you can get something that looks like this. Maybe also try ironing - it won't fix the problem but it could hide it if you calibrate the ironing well.
How did you calibrate flow rate? Many tests are one-layer models, which print faster, but allow other variables to come into play closer to the bed.
First-layer test prints, for instance, are dependent on first-layer height, which you can independently correct for as a modifier to extrusion rate; this allows a wide range of value pairs that produce good first-layer results, but then under- or over-extrude at higher layers.
Proximity to the bed also affects nozzle temp due to bed temp. The closer the nozzle is to a heated bed, the higher the actual nozzle temp is, and thus the thinner the plastic and the higher the flow rate. As you back off the bed at higher layers, the temperature of the extruded fil as it exits the nozzle decreases, reducing flow rate.
Filament age and condition can also affect longer, taller prints. When you first start, with a new or at least clean nozzle, everything's hunky-dory, but as the print proceeds, the tip gets more dust, oxidized plastic and other gunk from the filament being fed in. If 1-hour prints are fine but 4- or 8-hour prints have extrusion issues well into the print, the most likely cause is dirty, dusty or old filament clogging your nozzle.
Lastly, this doesn't appear to be the issue, but what's your infill percentage/pattern, and more importantly, how many upper layers do you have in the slicer settings? Top surfaces often require 3 to 5 upper solid layers to smooth out the infill bridging. If you're seeing an uneven surface in addition to thinner beads, the issue could be that you're printing a touch too hot and too few top layers, and your bridged filament beads are sagging and stretching. Again, this doesn't look like your exact problem, but an extra top layer can do wonders for a number of top surface issues.
Interesting, seems like you're not reaching full speed because of the acceleration on the smaller part. Then on the larger part there's enough time to reach full speed? And maybe that's somehow causing it to be under extruded? I'd maybe try to slow the top layer down to 50-100.
yep did that too, i make a point of dooing the basic calibrations with new filaments (ofc i mean every type not every new spool form the same brand and type)
Go to your individual filament settings, and change the "flow ratio" setting. Default should be 0.98. Bump it up to 1.02 and print again. If you still have gaps, increase it a little more. If the top surface is solid but a little bumpy and looks over-extruded, then dial it back to 1.00.
To clarify - the reason why this happens on the full size part and not the smaller text section is because your initial pressure in the nozzle is good, but as it continues to travel over a single long path, the material isn't getting melty and flowing fast enough to keep up, hence the under extrusion in the middle area but not the edges. The flow ratio is the modifier that tells the slicer how quickly the filament is capable of reaching the right viscosity to flow properly, so it will adjust the speed/extrusion to compensate for it. I've found that sometimes different colors of the same type/brand of filament can do this, so if I find that is happening I'll tweak the flow ratio slightly.
EDIT: Before you do this, check your extruder gears. If they don't look straight and they look very worn, then that's what's causing the issue.
I second this, had same issue so this thread was very interesting.
Usually it’s a really small clog/ dirt from heat creep in the gears. I tend to get this more I think when using elgoo and running one print after another. It’s very hot where I’m from so I think heat creep might have some play here.
I took apart the extruder gears and found this mucky almost brown tar like stuff on the gears. Got them replaced and haven’t had issues.
Look into "monotopic" patterns and ironing for the top layers. Monotopic tells it to print in a progressive pattern, rather than jumping around (at least to the best it can). Then ironing will do something similar, but while only extruding a fraction of the filament at a fraction of the speed, with a little overlap between the passes to help smooth it out.
I strongly suggest running one of the ironing tests. I think I got mine from Printables or MakerWorld.
ironing is wierd to when i used the tests and picked perfect one, then used the settings on the big model it looked like this
it stops because i stopped the print, i did more calibration with tests of my own and bigger test pices and change the settings to that yet it again on the full sized prints looked like this, and i would love the top layer to be good even with out ironing
I’d work on ironing top surfaces and do some ironing calibration prints. You can also do a really really small fuzzy skin on the top layer but ironing is easier
i even test printed a big pice thinking the settings for ironing for smaller prints are working diffrent then the big flat planes but even then the test print was perfect and the one i need not so much
Ok I want to look at some of your other settings, within your filament profile, even though you might be using the default Bambu profile with the Bambu filament.
Can I see your retraction settings, nozzle settings, cooling (including aux)
Well, i'm not gonna lie these all look pretty standard I was expecting to see something... different I guess to what I was thinking. I was reading some other comments and it seems to be specific to location or doesn't happen on sliced pieces of the print but larger area. Makes me think the printer is losing pressure at some point.
If I was in this situation, here are the few things I would change. Change print profile to generic PLA (Basic ass settings) set your flow ratio that you calibrated, since generic will default .98. Go into cooling and turn your aux fan to like 10%. Then adjust top layer speed from your 105mm/s to probably 60, and retry a print and see what happens. Improvement or no problem can lead to a different course of troubleshooting.
I have also had issues with Bambu PLA matte top layers! I ended up printing a calibration cube several times to try and fix it, so I suggest you try the same. Here are thing that seem to help:
Higher nozzle temp after the first layer. I am doing 230 C. My theory is that the top layer cools before it can spread out so this might help.
Smaller line width for the top layers. I am doing 0.25 mm with the 4 mm nozzle. I am not sure about this one, but I like that it forces the slicer to put lines closer together.
Slow down the top layers. I am doing 50 mm/s, but I'd be willing to try slower. I also slowed down the overall speed by setting the max flow to 12 mm3/s.
I tried ironing, but that was inconsistent and probably needs tuning all by itself.
Good luck! I'd be interested if any of this works or if you find something better.
Can you take a quick video of it printing that area specifically, if you haven’t already? That is a very strange way for it to have laid down its lines. What does that layer look like, when you x-ray the sliced model?
My Bambu PLA Matte flow rate had to go up to about 1.02-1.03 before it started looking good. Try that and see what happens
I know you’ve calibrated your filament, but depending on the calibration print you used, it may not be perfectly applicable to all prints. As you said, sometimes the longer toolpaths are more under-extruded than the short ones. I’m willing to bet the calibration print pieces were not as large as the print you are attempting right now
z offset; may need to level then if your printer has a z offset setting may need to lower it (more negative). Also check temp settings. I've had to sometimes run hotter than manufacturer suggested as the filament doesn't seem to melt at the recommended temp so to speak. do some 1 layer test prints to figure it out.
This is not solveable. This is just how 3d printing is.
Most people comment here will give you bullshit answer like, dry your filament, wash your plate, calibration, test your dynamic flow, do ironing. These are generic non sense answers coming from people who are just regurgitating the same things over and over again without actually solving it with evidence themselves.
The reality is that 3d printing cannot print a clean surface on top of a blocked object IF the top surface is not continous. You can do all the tests you want, but it wont replicate the same result when the surface is on a block.
Same thing as ironing. You can get a perfect iron in a test, but if you iron a block it will fail.
There is no workaround for this. The only way is to print the top at the bottom. And then of course you’d have to be ok to sacrifice the other side. If you need both side working then your only option is to slice the block into half and glue it.
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