Random blobs/globs on print during printing
Every so often I get seemingly random globs of filament on my prints. Of course, I never see it actually happen at the time but during random checks, sure enough, there will be a blob/glob of filament. It's not consistent with any particular STL file. And once the glob dries (almost immediately, of course), the next layer that comes across runs into the dried/hardened filament, makes a heck of a noise and either knocks the print off of the print bed or just goes over it and ends up messing up future layers.
Below are a couple of (not so great) close up photos of example globs.
Has anyone run into something like this before and know what causes it? The first photo is a third-party STL file but the second one is the Benchy provided with the Mini+. Up until that point, the Benchy print was awesome.![](\Users\jeffr\Downloads\Image2.jpg")
RE: Random blobs/globs on print during printing
if the first picture is your first layer, it looks way too high.
have you changed your nozzle recently? did you perhaps use a mk8 nozzle?
the drip, looks like waste material caused by an improperly fitted nozzle.
A Mk8 nozzle is shorter than an e3dV6 nozzle, so fitting one to a prusa can both mess up the first layer calibration, and cause the filament to leak in one fell swoop.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Random blobs/globs on print during printing
Too high? Hmm. My current Z height is -1.625 and, with that value, I get the filament to lay just about right on top of the steel sheet. The default value is crazy high as the filament has to drop a good distance from the nozzle to the sheet. Even -1.300 requires the filament to "fall" from where the nozzle extrudes it to lay on the sheet. Any value closer to zero introduces the "fall" such that the 90-degree angles during the first layer calibration are no longer 90-degrees.
I changed my nozzle a while ago (although I don't print 24x7). I have a few of the "Nozzle 0.4" nozzles and used one of those to replace the original that came with the MINI+. Although I've managed plenty of good prints during the change, perhaps I messed something up and introduced the globs. :-/ So maybe it's time to try and replace it again.
RE: Random blobs/globs on print during printing
Or should I be using the "Nozzle E3D V6 0.4 mm" with the MINI+ (not the original)?
RE: Random blobs/globs on print during printing
if they are all wrong type of nozzles, changing them will make no difference.
the screw thread on a mk8 nozzle is approximately 1mm shorter than the screw thread in an e3dV6 nozzle, they are not compatible.
it's important to use the correct nozzle type. Prusa printers use E3Dv6 style nozzles
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Random blobs/globs on print during printing
I think we cross posted
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Random blobs/globs on print during printing
So I purchased several of the "Nozzle E3D V6 0.4 mm" nozzles (this is what my order indicated) and what I received were actually labeled "Nozzle 0,4". I am taking this to mean that those two products are one-and-the-same (even though the former are more expensive than the latter, and I did pay the listed price for the former).
With the Nozzle 0,4 nozzles I was sent, I replaced the nozzle and now see what the problem is. After/during each print, filament is leaking out of the side of the nozzle where it is screwed into the housing. I presume (because I never actually see it happening) that the left over filament on the nozzle is heating up during the next print and dropping down onto that print whenever it gets to the required temperature. This is the same type of nozzle that I replaced last time (which led to my original post).
At the moment, I think all I can do is clean the nozzle before every print (setting the nozzle temp to 290C and letting the filament burn off). It certainly appears that I've got the nozzle all the way in as I can't (easily) tighten the nozzle any longer. It's straight and, save for the leaking filament, the prints come out as expected.
Are the nozzles I was sent the nozzles I ordered? And should I expect different behavior from the nozzles I ordered (assuming I'd get them and use them)?
RE:
E3d nozzles have dimples in the flats of the nut. To define the size. Non e3d nozzles have numbers.
If I recall correctly. The screw thread on a proper nozzle is 7.5mm long.
Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Random blobs/globs on print during printing
Ah, ok. Thanks! These nozzles have 3 dimples on them which corresponds to the image on the "Nozzle E3D V6 0.4 mm" product page. The text on the label stuck to the packaging threw me off. 🙂
RE: Random blobs/globs on print during printing
Dimples are good,
SO FAR, i have never heard of duff nozzles with dimples... Chances are you have the nozzle hard against the heat block, and the heat break not firmly tightened against the back of the nozzle.
the seal should be between the nozzle and the heatbreak, and the nozzle hex shoulder, should not be touching the heat block
I know this picture is the Mk3 hot end, but the idea is the same with the mini.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Random blobs/globs on print during printing
So after I changed the nozzle and performed a quick print (45 minutes), I didn't see much of a problem. And I do have the tiny gap between the nozzle and the heat block. However, now that I've attempted a 5h print, I got through about 90 minutes and it appears that the melted filament is coming out of the top of the heater block (then running along the front and size of the heater block down to the nozzle and dripping from there). When changing the nozzle, it's certainly possible that I loosened the heater block such that the liquid filament is coming out the top.
Is that what you meant when you wrote "the heat break not firmly tightened against the back of the nozzle"?
So I know how to tighten the nozzle but how can I tighten the heater block towards the heat break (if that makes sense)?
RE: Random blobs/globs on print during printing
Yes.
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Random blobs/globs on print during printing
So I know how to tighten the nozzle but how can I tighten the heater block towards the heat break (if that makes sense)?
I haven't done this, but it looks like these instructions would cover that: https://help.prusa3d.com/guide/how-to-replace-a-heaterblock-heatbreak-mini-mini_122769
If you pull out the heatbreak though, you'll need new thermal paste to reassemble.
You may also be able to loosen and slide out the heater and thermistor, then with the nozzle out, rotate the heaterblock like a screw up towards the heatsink one turn, and re-install the nozzle/heater/thermistor. But the thread pitch on the heaterblock may be too much, and one full turn may make the nozzle stick out too far?
Before you try to fix that, I'd personally compare the original nozzle to the new nozzles. Make sure the length of the threaded section of the nozzle matches between nozzles. If for some reason you got the wrong nozzle, you don't want to be taking apart your hotend to fix it for the wrong nozzle. If you have the old nozzle and didn't throw it away that is. If you did throw it away, I have some spare nozzles I can measure for you.