What might cause these effects?

I’ve been printing with silver M3D ABS-R (PETG-based) and I’ve been getting these pockmarks (circled in yellow), for lack of a better word. They’re not terribly detrimental to the structure, but they sure are ugly. What are possible causes? Too much retraction? Partially clogged nozzle? They occur regardless of nozzle temperature.

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you have been attacked by evil nanites that will take over the world… head for the hills


Not entirely sure if this is 100% what the problem is, but it may be related to it:

I have also been experiencing the same problem. I haven’t tried to stop it yet though haha.

Hope it helps!


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Overextrusion - set your flow rate a percentage point lower.

Phil, I meant filament
Product Designer @ id-z.one


Wouldn’t overextrusion cause blobs instead of pits? I’m thinking maybe it’s actually underextrusion. I remember seeing that some people have bumped up their flow percentage to 110% or so.

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I have a print going at 105%, so we’ll see.

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Underextrusion is the likely cause. I saw a significant improvement just going to 105%. It’s not perfect, so I’ll probably go to 110% on the next print.

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Calibrate your extruder as mentioned by @rick (Thanks Rick :smiley: )

Here’s the tutorial on how to do it (I did it with Octoprint, but it can be done with other slicers :slight_smile:

And here is the original post by Rick :slight_smile:


I printed an object last night at a 110% extrusion factor and had zero pits in the surface. It wasn’t a particularly tall object (45 layers at 0.2mm/layer), so I’m not willing to call the issue 100% resolved just yet.

Did you attempt the extruder calibration?

I don’t have the time to do that these days. I’ll probably get to it eventually. I did discover that the Snapmaker FFF file was using an extrusion width of 0.42mm, which is only 105% of the nozzle diameter. Simplify3D defaults to 120% of the nozzle diameter = 0.48mm, so I suspect that this is really where the problem lies. I changed the extrusion width to 0.46 and the extrusion multiplier back to 1.0 to give me what should be equivalent extrusion. I have a print going overnight that should tell me.

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Hi @TheBum @X_Pilot @Tone

I feel like a neanderthal watching gods share their unique knowledge. Thanks for sharing all this great information, it really is appreciated and adds to my education.

When i grow up, I want to be just like you

Doug the Neanderthal, wishing you a great weekend.

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Haha @doug! I’m still learning too!

@TheBum It took me about 10 minutes to do the complete process because I triple checked haha :slight_smile:If you’ve solved it with the extrusion width and multipliers then that’s awesome!


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Upping the width to the value suggested by Simplify3D (0.48mm) and leaving the multiplier at 1.0 has gotten rid of 95% of the pits I was seeing. The remainder seem to be toward the beginning of each extrusion line and are hardly noticeable. Still, I want to get rid of them if I can, so I’m experimenting with the Wipe feature of Simplify3D. The first print with Wipe turned on and set to the default length of 5mm came out very nicely, but I’ll need to do more testing with taller models.

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First of all sorry for my English, I’m good at reading but not very good at writing it (long texts especially) :slight_smile:

I’ve got the similar looking problem. Everything printed smoothly and then all of a sudden there were gaps in the diagonal fillings (see the photo).

And the problem progressed - the more I printed the more gaps there were. The part on the photo was printed with the original Snapmaker PLA gray filament. The extrusion temperature was 205C (initial layer 210C), bed temperature 50C (initial 55C), printing speed 25 mm/s (initial 5 mm/s for adhesion). The code was generated by SnapmakerJS 2.4.5, though I don’t think that it is important in this case.

After reading this topic I tried to experiment with the flow and temperature. The same part was printed with the flow varying from 80% to 120% and extrusion temperature varying from 205C to 215C. No luck, the gaps were still there every time. And I remember there were no problems when I first started printing with the same PLA and later when I printed with PET-G.

But while sitting near the printer and watching the process I found out that sometimes there was a loud clicking noise and it looked like the gap appears right after that noise. Maybe those gaps are related to the moisture accumulated by the filament when the water boils in the nozzle and interrupts the flow? The reel is sitting directly on my printer without the “dry box”.

So I’ve opened a new sealed box of the same gray filament and tried to print - there were no gaps at all. I’ve managed to print two or three days without them and then they started to appear again.

So is it possible that the problem is moisture-related?

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You should try a new hotend.
The nozzle may be slightly clogged.
PET-G requires higher temperatures (I use about 230°C) so there might me some residue inside the hotend.
Maybe it is enough to change just the nozzle
I don’t know how moist the air is at our home but I store my PET-G (over 30 different ones) just in the open cardboard boxes for over half a year without any problems.

My snapmaker doesn’t like setting the flow over 100% and since I found the right settings for the temperature I stay with 100% and it prints just fine.


Thank you! I’m new to 3D printing so your advices are very helpful.

I was already going to replace the hotend with the spare one (the one that comes with the Snapmaker) a little later. I’ve bought a pack of spare nozzles and ordered a 0.4 mm cleaning kit. I believe I’ll be able to clean it if necessary.

The was no such problem with PET-G - no gaps at all. There were other problems though (for example the corners of the large parts almost always tried to come off from the bed after several layers making the whole object curved) so I decided to return to PLA again.

And I’m going to make a sealed dry box with silica gel and teflon tube for feeding PLA to the printer, maybe it will help. I don’t think that the air at home is very moist but I store all filaments sealed with silica gel just in case. I’m also going to buy a hygrometer :slight_smile:


3D printing means learning all the time…
I’m using the snapmaker for about a year but I still have some problems.

I want to give you a few hints:

1st layer adhesion and quality are the most important things for succesful prints.
You shold do this things if you have problems:

  • leveling the bed
  • use a skirt (3-4 lines at least) to prime the nozzle
  • first layer hights larger than 0,15 mm are easier to handle
  • 1st layer print at speed about 5-10 mm/s

Small details as holes in your print require slower speed!
You will learn what models have to be printed at what speed range - for such a small print I suggest 20-25 mm/s

If you use another slicer then snapmakerjs (like Cura or Simpolify3D) you can adjust the extrusion width to 0,36-0,38 mm to avoid the gaps between the lines:

To avoid these strings you have to adjust the retraction and maybe use the Z hop at retraction:

I know these holes - they come from a bad flow inside the hotend when it is starting to cogg up and/or you are printig too fast and/or too cold:

I like following page because there are so many helpful hints:

Please have a look at the SnapLinks-Wiki:


Thank you very much for the detailed hints and links. Right now I’ve got rid of the holes by doing two things: replacing the whole hotend kit with the spare one and cooking the possibly damped reel of filament in the oven at 40C for 9 hours. The holes have gone for now.

Here’s what it looks like after replacement:

There are still problems with the hole walls but I’ll deal with them later.

By the way, the old hotend had a lot of melted filament inside but it all was gray from the latest prints. Before that gray PLA I printed with “natural” (white-ish) and black PET-G and there were no residues of that color. But I still believe that it was clogged since the replacement of the hot end saved me from the holes.

Yes, I agree that 3D printing involves constant learning. Some things I’ve already learned and the whole lots of others need more experimenting. I always print with a skirt, it helps with the first layer adhesion somehow. As to the speed, now I use 10 mm/s for the first layer and 25 mm/s for other ones. I used even slower speeds before I read that the nozzle becomes clogged faster if the speed is too slow (can’t find the link now). Thank you for the hint about the small details - I’ll try to set all speeds to 10 mm/s and see how they come out.

The gaps between the lines have gone with the holes and the overall surface quality is much better after the hot end replacement. I’m using SnapmakerJS and it doesn’t have “extrusion width” parameter but I’m going to try Slic3r and Cura some day (Simplify3D requires the Internet connection to launch as I remember).

As to the strings you marked on the penultimate photo - these are strange things. I print with the 5 mm retraction, retraction speed 20 mm/s and 1 mm z-hop. But the printer doesn’t perform a retraction where those strings are. It retracts only when it needs to move through the air. For example, when printing the part on the photo the retraction happens only during the creation of four L-shaped things when the nozzle moves from one part to the other. There is no retraction when the space where the nozzle travels will be filled later. For example the printing of the holes looks as follows: the wall of the first hole is created, than the head slowly moves to the position of the second hole leaving the line of the filament as if the extrusion continues. So all hole walls on each layer become connected with the “ridges” of the filament. They are covered with the diagonal filling later but remain visible and can be felt by touch. Maybe it’s a slicer-related problem, I’ll find it out when I try other slicers.

I’m printing with PET-G and will never use PLA again.
My retraction settings are 3 mm @ 50 mm/s with Z-hop 0,25 mm.

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