PETG Nozzle Blobs  

RE: PETG Nozzle Blobs

It wouldn't hurt to provide a 3mf (zipped, of course) so we can look at the slice details. Size, layer print times, that sort of thing.  Dropping blobs can be a number of things, from leaks, the nozzle picking up small sections of extrusion off the print bed, or even missing support structures for overhangs. So photos of the problem are also important.

RE: PETG Nozzle Blobs

@tim-m30

What is a 3mf?  I'll be glad to do that if I can.

RE: PETG Nozzle Blobs

In Slicer, File Export Project as 3MF - save the file, create a compressed ZIP, and copy the file into the ZIP.  Drag the zip into a post just like an image.

A "project" has everything needed to recreate what you did for settings, rafts, supports, the part(s) ... It's also a good way to archive a print that turned out well so you can get back all of the settings used.

RE: PETG Nozzle Blobs

@tim-m30

Slic3r doesn't appear to have that export option.  It does have an amf file export (which actually looks like a zip file itself) so I exported with that and put that into the attached zip file.  I did two of them, one is a PLA (the KT_ARM...) and the other is a PETG (Cover-IR).  Pictures are included of the results which neither are really great.

The KT_ARM_LARGE... one, I thought was going OK although the back edge of the flat area is extremely rough with little spikes sticking out.  But after it was working on the upright pole sections, it must have created a blob that attached to the piece and ended up breaking it free from the build plate.

Vertical uprights where it has to jump section to section (which is the same when I'm printing multiple small items) is where it seems to be the worse and builds up the blobs.

The Cover-IR is relatively flat.  With previous comments above, I've turned the nozzle temp down to 220 (which is actually 10 below the min desired for the filament).  It does seem like that lessens the blobs, but the item is very rough feeling and dull finish, so I think that temp is too low for it.

Let me know if these amf files are not what you were wanting.  I included an image of my Slic3r Export options to show what I have available.

RE: PETG Nozzle Blobs

Sorry - the menu is File -- Save Project as, not Export ... 

RE: PETG Nozzle Blobs

First problem on the larger parts is the fillet, or rounded edges on the bottom of the part. You really need these to be chamfers for best results in FDM printing. That said, I'm guessing because I don't have the project. But I'd guess you are trying to print too fast. Even perimeters that should be working are pulling free on inside corners. That probably translates into loose small segments in other places. These unattached segments of filament stick to the nozzle and melt and drop elsewhere.

RE: PETG Nozzle Blobs

@-2

Here is my updated file with the 3mf files in it.  I've read something about speed, but I never have been able to really figure out what I should adjust to actually check that.  Most of my settings are default settings (which seemed to work fine before converting to the MK3S upgrade.)  So I'm open to any suggestions on what I might try changing (but may need as much instructions as possible to do that) since I'm still very new with this.

RE: PETG Nozzle Blobs

Test with 5 C lower nozzle temp( I was printing 240C) and lower extrusion multiplier with 0.3( or a little more).

I had a petg print that hat stringing and blobs sitting on top of model, and nozzle hitting the blob. And my nozzle was getting dirty with filament on it, after adjusting it was gone.

You can do this wen the model is been printing.

RE: PETG Nozzle Blobs

Hi @peter-m-3

So for the extrusion multiplier, I see in my Slic3r, it's currently set to 1, should I set it to .3 or .7 (.3 lower)?  I wasn't exactly sure what you meant.

Thanks,

RE: PETG Nozzle Blobs

Yes, try 0.3 lower, then start printing.

If still blobs, lower temp a little.

if still not good lower extrusion multiplier even lower, normally 0.3 should be enough.

Every filament is different.

And normally you need to measure  the filament thickness, what normally nobody does(I think), and change this in the slicer.

Printing will never be slice and print and I am ready, you have always to change somethings, if you want to avoid this, you could stay with 1 company with 1 sort of filament.

RE: PETG Nozzle Blobs

@peter-m-3

If I go anything below 1 for the Extrusion multiplier it seems like I can't get the printing to stick to the bed.  It's getting very thin lines laying the initial lines and they pull up as the head is moving around.

I did try lowering the print temp to 235 and 230 didn't make any difference, it still blobbed.

I tried lowering the fan speed down to a Max of 20% (and Bridges down to 30%), didn't help.

I tried changing the Retraction Length to 2 and didn't help.

I ran about 2 feet of cleaner filament through it and still didn't help.

I have noticed that when it first starts to extrude filament, the very beginning flips up to the side.  If I'm testing extruding a good amount, it bunches up at the beginning until it finally drops down and then the extruding comes out in a straight line.  I'll try to include a picture of what I see when it first starts extruding (with the extruder raised up and I'm extruding a set amount).

What are the indications of a bad print nozzle?  I've never changed mine yet, so I don't know if that's one of my next steps to have to do.

RE: PETG Nozzle Blobs

I also noticed when I was running the cleaner filament through, the screw that sets the tension for the filament feeder (sorry I can't think of the correct name, it's late) was loose and the cleaner filament stopped at one point.  So I adjusted that until the filament started flowing correctly again, and hoping that may have been the issue, but it didn't help after I put the PETG back in and did another test.

RE: PETG Nozzle Blobs

Hot PETG is pretty sticky. I had some PETG prints with horrible surface finishes cause it was sticking to the nozzle and dragging the stuck plastic back and forth depositing it randomly. I just back off the live-z about 0.02 (+0.02 higher) and it stopped.

Google "PETG Live-Z" and see if the issue you have are similar. Backing off live-z is what worked for me.

RE: PETG Nozzle Blobs

Change nozzle, use the e3d online manual.

It's 10 minutes work and you know if it is the nozzle.

RE: PETG Nozzle Blobs

@print-my-world, thank you, I'll give that a try maybe before I replace my nozzle.

@peter-m-3, thank you also, I'm off work most of this week so that will give me some time I can attempt to do this.  I just kept thinking it wasn't the nozzle since it was fine before doing the mod to the MK3S.  But since it seems like I've tried everything else.

RE: PETG Nozzle Blobs

@peter-m-3

Well, I kind of feel dumb, but it does look like (so far) that it was the nozzle causing all my problems.  I did get it changed (my first one!!) and the first thing I printed using the Generic PET setting of Slic3r (so no changes made) and the item I printed turned out beautiful with a nice clean top and no stringing on it, although it was just a small replacement filament feed cap for the printer so it wasn't a difficult item, but compared to my previous 3 attempts to print it, this one was perfect.  I'm printing the item that I had posted the pictures of before that messed up between the 4 raised pins it has but doing it in PETG this time to see how it works.  So I'll post one more time for the status of this result tomorrow when it's done.

I could see where on the nozzle that I removed, I have always used my needle nose pliers to remove the initial filament just before it starts printing.  I must be sliding the pliers down the sides of the nozzle to do that, and it looks like over the time, I must be wearing down the sides of it.  The nozzle hole actually looked like it was slightly at an angle.  So I will have to keep that in mind and stop doing that!

At least this gave me a reason to open up the enclosure around my printer to get access to it easier, and I was even able to fix my filament sensor issue I was having by putting a small spacer under the IR sensor.  Now that appears to be working perfectly also.  So this was a double win for me.

RE: PETG Nozzle Blobs

@jmharo

Good news that you found the cause.  

RE: PETG Nozzle Blobs

Yep, everything has been printing great now.  So I'm happy now.

I want to thank all that worked with me to give me all the possible ideas.

RE: PETG Nozzle Blobs

This thread perfectly describes the issues (and attempted remedies) I've been having with PETG - it's been extremely helpful. Many thanks to everyone who participated.