UPDATE: turns out the issue was the mode l was trying to print!
After lubricating everything, removing then retightening screws from all over, cleaning the bed, scrubbing the nozzle, it looks like my issue was actually from the model I was printing with. It had a razor thin edge as its base, and the printer either a) printed a very thin line of filament, which could easily shift due to having no structural support or b) did not print a first layer as the bottom may have been seen as not touching the base. Either way, my fix was moving all my print files down by 4mm, creating a flat base for the print as it cuts off the thin edge! For my use case, this was fine as shaving off 4mm from the bottom does not affect the functionality of the mask.
This also explains why the smaller models I tested printed fine (a Benchy + a controller mount), as both had very flat bases.
original post:
When trying to print larger models (in PLA), I run into an issue where the filament does not correctly adhere to the printing bed. I have tried cleaning the nozzle with steel wool and washing the build plate, but the issue still occurs. It is probably something to do with the settings on larger prints, as smaller models (controller mount, Benchy) all print perfectly fine.
In all occurances, it seems like the first few layers do not correctly join together, and the print becomes a thick web of filament string (not a fine web, but a thick one where the strings are about the thickness it was printed in)
Does anyone have an idea on what could be causing the issue?
the models I am trying to print:
- https://www.thingiverse.com/thing:6783537/files (the mask of the Hollow Knight guy)
- https://www.printables.com/model/19648-channelled-nail-from-hollow-knight (his big sword, at around 0.6x scale all dimensions)
I am using OrcaSlicer and a Bambu A1 (note: I no longer recommend Bambu printers, this was bought before the firmware updates that blocked third-party software support outside of LAN only mode)
My slicer settings are close to default, but with gyroid infill, 3 walls, and tree supports. Those settings work with smaller prints, so I’m decently sure they are not the problem. My printer was sitting unused for a few weeks with the filament exposed, so perhaps the filament became too wet? But small prints work fine. No idea what is causing this issue though.
edit: I have printed a large first layer test print, and I see many imperfections on the surface. What does this mean?
on the print bed
on the floor
edit 2:
Tightening the four small screws behind the heating assembly did not fix the issue. What else could be going wrong?
Looking more closely at the models I am trying to print, it looks like the base is very thin and isn’t flat. Could that be why the first layer easily shifts? Maybe I need to manually add supports, since OrcaSlicer only adds supports to either end of the curve. I will try that and report back whether it works!
Yeah that’s a terrible orientation for bed adhesion. Have you tried orienting in a different manner that provides a larger contact area with the bed?
I was able to print by lowering the models by 4mm, making the bottom flat enough to correctly adhere! It turns out that it was an issue of the model, not my hardware
Why not just orient it in a different way so a flat surface was touching instead of cutting a part off?
It’s only 4mm, so it’s no big deal. Plus, this is a helmet shape, so the other sides are round (and therefore need more supports, using more filament and such)
Maybe try a different bed temperature? And I got some improvement after cleaning the bed with alcohol.
Is there any location specific that causes adhesion issues? Bambu printers aren’t known for warped beds, and have ABL, so this isn’t likely. On my older printers I print a 1 layer tall square that’s 20*20 mm to test my z offset. It’s in a 3x3 grid (can do 4x4 or whatever) so I get a good idea of where my plate has issues.
Check mechanical connections so it isn’t caused by slipping on gears/rods. Have many hours of printing since you gave it a good thorough service?
Also, what filament type is this?
It’s PLA, forgot to mention! Have edited the post with that detail.
It doesn’t look like any of the motors or such are slipping. I have also lubricated the rails of the moving bed recently.
Have you checked that all the grub screws are properly tightened?
Try turning off the setting that turns off the headed bed after a few layers.
Otherwise post a pic of your first layer.
My printer keeps the bed heated until the print is finished. Don’t think that’s the problem!
My attempts at printing the large models (see how they are all stringy, the filament is not stuck together as a solid object)
Post a pic of the first layer on the bed. I suspect your z offset is too high and you need to smush it into your bed more.
I have edited the post with a large first layer print. There are many imperfections, what does it mean?
How old is your printer. ?
I had near 2000 print hours and started having first layer problems. I did a lot of troubleshooting and nothing worked.
Ended up being that the heat block needed replaced. Even though it seemed to be functioning. It was causing flow errors or something.
It could also be that the screws around it get loose. That’s actually been most people’s issue but that wasn’t mine.
I replaced the heat block and it fixed it. Here is a link to the thing I’m talking about. Explains to check screws first before considering replacing the heat block.
Hopefully that’s your issue cause that’s easier to do than replacing the heat block.
A poor first layer may not be super noticeable at first. But the problem for me was it got worse over time and did result in prints lifting.
https://forum.bambulab.com/t/are-you-having-issues-with-first-layer-heat-block-solved/110665
My printer has 676 hours. I will try looking for the screws of the heat block and see if any are loose!
Be sure to check the screws on the backside. You will need to take out the front three to access it.
https://forum.bambulab.com/t/a1-mini-a1-users-solved-screw-fell-out-of-toolhead/97626
I have tightened those screws now, will see if that fixes the issue. Some of them were not fully tightened. I will see if the print works correctly…
In all occurances, it seems like the first few layers do not correctly join together, and the print becomes a thick web of filament string
A pic would help but that sounds like bed leveling. That happens to me on my S1 bed that has low spots where the bed screws are under the plate. So while the bed is “level” there are some shallow pools that the automatic bed leveling isn’t compensating for and I get that effect if I print in that spot.
I’d suggest printing a layer 1 test print. https://makerworld.com/en/models/953670-1-layer-first-layer-test-print-benchmark?from=search#profileId-922200
You want the test print to look like a perfect sheet of paper.
First layer test print worked fine for me, quite smooth aside from a few bumpy bits. This is a 60x60cm square I found on Printables.
There are minor bumps near the middle, are those of any concern? This is immediately after I used the automatic bed levelling function
It’s a little hard to see due to low resolution, but it looks like you have small gaps between infill lines. If that’s the case you need to reduce Z-offset to get more squish.
It could be the lighting but when I do a layer 1 test print it looks like a sheet of paper without the large ridges like on your print. Does your sheet hold together like a sheet of paper or is it stringy?
It does feel like a sheet and isn’t stringy
The bent bit in the corner was from me trying to peel it off the build plate, ignore that
