Popping noise and bubbles
Hello. I've had my pre-assembled printer for about 3 weeks now and things were going great. After some attempted modifications, I noticed a clicking/popping sound during my prints and after closer inspection, I noticed bubbles in the plastic when I would purge the extruder. I think this started happening after I did some tinkering, but maybe I'm just being more observant for issues.
I started building some dry boxes I could print from and wanted to extend the PTFE tube so I could hook it up to a dry box. Before realizing I just had to take off the piece on the side of the case and replace the tube there... I started at the extruder and tried to yank the tube out with some pliers before realizing I could press that little ring in to release the tube. This action is what I thought might have caused an issue.
But for trouble shooting, I've tried a few things:
- Freshly dried PET-G filament, and brand new and dried PLA filament
- Different nozzle (0.4mm HF, and 0.4mm hardened)
- Cleaned both nozzles with needle.
- Higher nozzle temperature.
- Directly fed filament into extruder (to make sure PTFE tube wasn't severely messing things up)
- Ran calibrations again, including the gearbox calibration.
Prints are still coming out ok, but the bubbles worry/annoy me. I do plan on replacing the inside PTFE tube soon since I definitely smooshed it a wee bit with the pliers. (If someone wants to give me a tip on out to remove the tube from that side sensor before the tubeexits the case, I'd appreciate it!) Any idea what to try or check next to fix this bubble/popping issue?
Best Answer by Diem:
Bubbling, fizzing and popping are classic signs of damp filament. It sounds like you are already heading in the right direction but perhaps you need to dry your filament even more than you have been.
Cheerio,
Bubbling, fizzing and popping are classic signs of damp filament. It sounds like you are already heading in the right direction but perhaps you need to dry your filament even more than you have been.
Cheerio,
RE: Popping noise and bubbles
Hmm ok. I did the recommended heating on both, and they are sitting in boxes with silica gel with a sensor that reads 20%-24% humidity. What humidity should I aim for? I'm afraid to keep them in the dryer for too long. I've been using this dryer I got a few days ago (with my own built box). Should I leave the filament hole open while drying?
I have been building some cereal dry boxes that are popular on Printables so you can print directly from the boxes. That is the only other major thing that has changed with my setup the past few days.
RE: Popping noise and bubbles
Totally agree that this is a classic symptom of damp filament. I've found in the past though that certain brands of cheap filaments exhibit this behavior no matter how much you keep them dry which is why I only use the "premium" filaments like Prusament, Overture (which I like) etc.
I usually aim for 10%rh, I don't always get there. Below 15% generally works OK.
I don't know that particular dryer so I can only refer you to the manufacturer's instructions; like many here I use food dehydrators.
Cheerio,
RE: Popping noise and bubbles
Ah ok, thanks! I cooked them again last night. I realized 2 things. First, that the dryer works in 3 power levels, not in temperatures. The humidity meter's temp reading was showing that the dryer wasn't reaching nearly the temps needed, so I bumped up the power last night, though it still came up a bit short of the 60°C for pet-g.
The other thing I learned is that these humidity meters aren't accurate under 20%. The lowest I could get them to read was 18%. I'll try them out later today though and hopefully no bubbles! Thanks
RE: Popping noise and bubbles
Do I need an industrial oven or something? I open a fresh PET-G roll and immediately through it in my dryer at the recommended temp and time. Then I immediately throw it in a dry box to print out of. It is still bubbling. Not as much, but still a decent amount. Is PET-G just difficult keep dry?
RE: Popping noise and bubbles
I suppose since a hardware had been ruled out, then this thread should probably stop, sorry. Just a tad frustrating that it is still bubbling 😅
RE: Popping noise and bubbles
I suppose since a hardware had been ruled out, then this thread should probably stop, sorry. Just a tad frustrating that it is still bubbling 😅
It could just be bad filament or maybe the heat block thermistor is bad and the nozzle temp is too high. One thing you can try is download a temperature tower from Printables for your filament type and run a test.
Is PET-G just difficult keep dry?
It very much depends how the spool has been stored and for how long.
If the roll has been left long enough to saturate all through then you'll need a loooong drying time. Typically a dry spool will absorb moisture into the outer layers and relatively short drying will pull it out again — but if wet all through it's easiest to dry, bag with desiccant, wait a few days, dry again drying the dessicant too, rebag and repeat until tamed. The pauses allow the moisture in the inner layers to migrate to the outside.
Cheerio,
RE: Popping noise and bubbles
Maybe I'll give that temperature tower a go. I thought maybe this polymaker dryer was just no good. I bought a food dehydrator that seemed to work well while it was running. I opened a new Overture matte pla and dehydrated it at 50°C for 7 hours. Popped it into a dry box and started a print the next morning. It too is bubbling 🫠
RE: Popping noise and bubbles
@klong,
How about a different alternative? When the filament is popping and bubbling what is it's consistency? Is it runny? I suspect that you may have damaged the hotend thermistor when you were attempting to take things apart. The wires to the thermistor are pretty delicate (I destroyed one myself by forgetting to unplug before I tried to remove the hotend assembly) and it doesn't take much force to damage them. It is possible (from experience) to damage the thermistor in such a way that the hotend will essentially "run away" without the printer being any the wiser.
If you have access to a volt/ohm meter you can check for continuity between the thermistor wires. Otherwise they are not too expensive to just buy and try replacing it.
Regards,
Steve
RE: Popping noise and bubbles
Definitely possible with how my first attempt at changing the nozzle went 😅. Although I think incorrect temperature was the biggest factor here. I tried out the temperature tower with both HF and hardened 0.4mm nozzles, and boy were the temp changes noticeable. I think I have the correct temperature dialed in now for my nozzle. I'm now doing the extrusion test cube to try and get the flow perfect. And there isn't a single bubble hole on this beautiful little cube. And I heard no popping while it was going.
So I've learned how important dehydrating and setting the right temp for new filament is... I'm definitely going to run the temperature tower and this extrusion cube test for every new filament I get.
Thanks for the help all, and sorry it ended up being a sort of obvious solution. I just assumed my nozzle tinkering broke something!
RE: Popping noise and bubbles
And keep in mind the thermistors are glass beads inside a thin metal shell. It is very easy to pinch and break the bead when tightening the retaining set screw. Finger tight using the short end of the Allen wrench is probably just over the limit of 'enough'.