Popping and bubbles in print  

RE: Popping and bubbles in print

Here is a example

RE: Popping and bubbles in print

it could be that there is moisture in your filament tpu is hygroscopic thus while printing a small pocket of moist 'plops' into the filament or your filament being used is not 'dialed' in into the slicer (eg wrong temperature etc)

RE: Popping and bubbles in print

@oxygen

Thanks, I will try drying the filament out but it did do it to some new sealed filament. I have change the setting for the filament and printed at different tamp but no change. 

I will keep you all updated on all the changes and see if can get it sorted. If anyone else is having this problem can you please post here.  

RE: Popping and bubbles in print

@ste

I had this problem while printing with TPU. There was bubbles in the print and while it was printing it was making a constant popping sound. 

I had to speed up my print speed. I increased the print speed by 70%. Once I did that, everything came out perfect. I was using spiral vase settings and had no retraction. Hope this helps! 

RE: Popping and bubbles in print

I've been having this same problem since starting with this Mini (borrowed from a friend as mine's pushed back to June), using a roll of CCTree PLA that my friend's had no issues with previously. I can hear the popping sounds, I can see the gaps in places where there shouldn't be any retractions (smooth portions of straight perimeter etc). It seemed to be more frequent at 0.15mm than 0.20mm layer height, and no evident change between Quality and Speed options in PrusaSlicer. I've upped the external perimeter speed to 50mm/s from 40mm/s to just make a change, and it's just as frequent. I'm currently printing my test cube at 60mm/sec Perimeter and External Perimeter (from 50 and 40 respectively) to see if it disappears, but I could see the first gap at the outer perimeter on the first layer (nowhere near the seam, which I placed at the back so I'd know).

I'm glad I'm not the only one with this issue, I'm just trying to work through it. It's possible this PLA has picked up a bit of moisture, it just seems unlikely.

RE: Popping and bubbles in print

I have the same issue.. first thought it was moisture.. but same PLA prints fine on my Mk3.

Printer was fine for the first 4-5 prints... and just started doing this recently. I cleaned the feeder gears, changed the nozzle thinking perhaps it got clogged..   still pops and wont print correctly... almost like it's too hot.  But I'm using 215 ( even tried 210 ) and the same PLA prints fine at 215 on my Mk3   

Hope someone finds a solution soon.  I really like this mini.  But right now I cant use it.

RE: Popping and bubbles in print

After some more research I found this video...  performed the fix.. and my printer appears to be printing again..

My heat block was a little lower, after this adjustment, and raising the probe, I did a first layer recal and it's printing great now.

RE: Popping and bubbles in print

Same issue here with new unpacked Prusament. Mostly on the first layer. I keep recalibrating and fine tuning Z without any success so far. Tried different speed, temperatures etc.. Printing with a raft is better 🙁 . Again, no problem with the MK3. Strange.

RE: Popping and bubbles in print

Hello, 

I am still getting this issue and have tried a lot. I did get some improvement Cheap black PLA by changing the filament Diameter to 1.70 after measuring the filament. My more expensive filament is still having problem and have changed setting but still no change. 

I will keep you all updated if anything changes.  

RE: Popping and bubbles in print

Ok. No bubbles anymore and the first layer now sticks very well.

I do not know why this happened. It seems the mini is very picky about everything that can fail.

I rebuilt the mini, checking all the screws. Pushed the heatbreak and reset the ptfe tube. Cleaned the sheet with Acetone. Replace the Minda (of course). Checked that the MINDA was horizontal (it wasn't) - I think you should not count on the prusa's prebuild state : it seems to be (sometimes) (very) unreliable.

Checked the idle extruder screw. Recalibrated the Mini's first layer. Then printed a cylinder and checked with an horizontal lighting that the first layer was perfectly flat (and used the Z offset live during print) : it wasn't.

The (included) first calibration scheme is not enough (!).

Then I tried to print a large surface : I succeed in having the PLA stuck on the bed increasing the PLA temp to 230. Prusament PLA. I know it is crazy, but, hey, it works.

So I changed the preset for prusa slicer : for instance, for a 0.2mm = 230 for the first layer, 0.3mm for the first layer.

And it works really great. BUT !... It seems that the Minda gives different results from one run to another. This may be related to MINDA temp (see another thread about that).

So, each time I switch on the Mini, I let the MINDA heat (10 mn) then I recalibrate using a print test for the first layer with ZLive tuning. And then, only then, I can start to print.

The results are very good if you can afford the recalibration time each time you switch on the prusa.

This is a neat little printer that can deliver but it is very picky about all. I don't think it is fair to advertise it as farm ready.  As for beginners, I think it can make many beginners give up very fast.

It is NOT a mini I3 MK3S (which I use and love). It is a prerelease mini printer very promising that need ironing.

So, be prepared to check all things twice (and that may not be enough).

(by the way thank you to all the girls/guys on this forum. VERY helpfull)

RE: Popping and bubbles in print

@gmenier

I agree 100%. My mini has been nothing but issue after issue. After tweaking it every which way it prints great but still some bubbling. Increasing flow factor from 95% after the first wipe to 100% seems to do the trick for me but it's aggravating that this setting will not stay inputted despite what I set in PrusaSlicer. The mini is a large beta test and maybe one day it'll be up to Prusa/Mk3 standards but right now it's hit or miss. This is especially sad because a lot of people are getting this as a beginners printer ... they'll have one heck of a time lol. Love Prusa but hoping for more fixes as they've been known to do to get this one to the level we know it's capable of. 

RE: Popping and bubbles in print

This is exactly what i'm experiencing right now! popping sound, holes on prints. One thing i have found is maybe mini is really picky for filament, cause the same filament i print with mk3s without any problem.

RE: Popping and bubbles in print

I'm also experiencing this issue on a brand new Mini, stock settings, 1-week old Hatchbox PLA that has been stored with dessicant and prints perfectly on another printer. The pops happen at roughly the same time after every travel retraction, so I'm pretty sure air is getting in through the nozzle and causing a bubble in the molten filament, which comes out after a predictable amount of time. If it was wet filament, it would be more unpredictable, and I'd have the same issue with this filament on my other printer. I have tried tuning retraction settings, but any lower than stock and stringing gets really bad - I'm seeing a lot of spider webs even with stock settings.

I haven't tried resetting my hotend position yet, but that does seem to be a likely cause. If there is a gap between the nozzle and the PTFE tube, that's a place air could hide after a retraction. I'm impressed overall by the Mini+ but it is a bit disappointing to have this issue out of the box on a pre-assembled unit using stock settings and stock g-code as supplied on the USB drive.

I think, i found the resolve of this issue

i am having same issue with my prusa mini+ while printing recorder (many round shape and hole). i used eSun PLA+ and suddenly the bubble popping and the surface layer of my object has many tiny holes (as the picture on second coment).

so i did what the video below, rise up my hotend closer and change my nozzle with e3d x nozzle, with nothing improve. still bubble and popping. 

and ridiculusly it wasn’t happened when i use prusament. print good and no popping. 

suddenly, it came to my brain to lower the nozzle temp, from 215 (default) to 205 (eSun recommend on the spool spec) and ….. the popping gone. still has one or two popping, but not frequently often. 

i think, the prusa mini has sensitive heater, or much higher temp than other printer like creality or voxelab. 

so try it guys, it may be help, but not 100% solved the issue. m

cheers and happy printing (tom-indonesia)

Posted by: @3dprintsbychris

After some more research I found this video...  performed the fix.. and my printer appears to be printing again..

My heat block was a little lower, after this adjustment, and raising the probe, I did a first layer recal and it's printing great now.

RE: Popping and bubbles in print

Since I started with my prusa mini+ (June 2021) I have more or less issue with it (extruder, hotend). I have the exact same issue since day 1 with popping and bubbling. At the beginning it was not a big issue, but it started to be one over time and ended with a clog.

I also see that the filament is currling, like there is a clog. The filament is a fresh spool of prusament that is dry. Same with other filament. So I'm 100% sure it is not the filament or moisture.

What I did / tested

• disassembled the hotend and extruder, cleaned it
• also replaced the heatbreak with a bondtech heatbreak
• replaces the nozzle multiple times (nozzle from prusa store). I will also test a genuine E3D nozzle

Now I'm playing around with retraction and temperature settings - a thing that shouldn't be needed with Prusaslicer and Prusament 🙁

RE: Popping and bubbles in print

Posted by: @william-3

..The filament is a fresh spool of prusament that is dry.... 

-means nothing. The only way to be sure that the filament is dry, is if you dry it yourself.

Clogs... If that happens almost regularly (at default slicer settings), then it means hotend isn't assembled properly. I have Bondtech upgrade on Mini for months and no problems so far (still using the nozzle that came with printer).
And no, with Prusament, there's no need tweak settings in slicer -for "normal" printing objects, result should be good at default settings.

RE:

Thank you for your inputs.

Bogdan, are you using the Prusaslicers default profile for Prusament just with the new PID settings or did you adjust anything else for your Bondtech heatbreak (like retraction)? 

I checked again the hotend and found out, that the PTFE tube was to short on the stock heatbreak. The spare PTFE tube was even shorter. I cut a capricorn tube in the correct length and put it in. I also tested the filament on another printer, there it works perfectly. Why it didn't work on the Bondtech one is frankly not clear for me - but out of scope for the troubleshooting for now.

At the moment I have some underextrusion problems that are seen on the first layer with the stock and the Bondteach heatbreak - I didn't have it before the clog. I will first troubleshoot this with the stock heatbreak, before changing to the Bondtech (just to make sure, there are no other problems). I'm a bit out of ideas and contacted Prusa Support on Friday - they just replied to check exactly this (hotend assembly, PTFE tube, extruder gear) - now I'm waiting for the response what could else be tested. I will of course write here as soon as I found a solution. If I have some questions about the underextrusion problems I will post in in another thread because it is not the subject of this one and possibly unrelated

RE: Popping and bubbles in print

For Prusament PLA, I use all relevant settings (temperatures, retraction, print speeds, fan, etc.) at default in PrusaSlicer. I never printed "test objects" (benchy and stuff), as there was no need for that -because I'm happy with print results. Btw. I always print with 0.20mm QUALITY setting.
Of course, depending on print object, it might be necessary to fine tune some setting. For example, when printing very small objects, then I decrease hotend temperature by about 5-10°C to reduce stringing -smaller objects are by default printed at lower speed and so extrusion is fine even at lower temperature.
Yes, I still use Bondtech's PID value, simply because I run modified firmware and I haven't updated to latest firmware yet. But according to Prusa's findings, that doesn't make much difference (if at all) -and I tend to believe that. Or let me just say: if printing with various filament types (PLA, PETG, ASA,...), then "perfect" PID value doesn't exist -it just can't.
But there's easy to check if PID value, that you currently use, is good enough: when printing, hotend temperature (shown on display) shouldn't fluctuate more than about +/-1°C (or max +/-2°C).

I bough Capricorn tube for "just in case", but never needed it (because I use Bondtech heatbreak since day one).

If there's extrusion problem (at default settings), then we only have two things to look at: hotend and extruder. If hotend is properly assembled, then no wisdom is needed (it just works). And with extruder calibration, you can quite easy check if extruder is the troublemaker.

Wish you success.

RE: Popping and bubbles in print

Hi Bogdan

Thank you very much for this information, this helped me a lot. At the moment, I guess I have to test the extruder, because it all started to happen after a jam/clogg and I had to clear the extruder gear (I had soft filament). The hotend was now disasembled so many times that I can do it in the sleep and even now from memory in which lenght I have to cut the PTFE tube - therefore I think this should be assembled fine. And the Problem is with the Bondtech and the stock heatbreak.

I will buy an extruder upgrade and test it. Again, thank you for your input