What does cause this kind of glitches (globs)?  

Re: What does cause this kind of glitches (globs)?

I saw a similar problem when printing with a wood based filament - it was down to over-extrusion. I tweaked down the extrusion by a couple of percent and the blobs disappeared.

Cheers,
Paul.

Re: What does cause this kind of glitches (globs)?

Yes it looks a bit over extruded as Paul mentions.

Looking at your top layer in the image, you have some gaps there as well, could you try reprint it with a 0.95 Extrusion Multiplyer and maybe lower the Z height around 0.1mm, and if possible take a photo of when it prints the first layer.

Re: What does cause this kind of glitches (globs)?

thanks for your reply guys. It's weird because I printed other things and I've never seen something like that.

Actually the whole model was printed correctly apart from the top part (the one pictured). I will try what you suggest, thanks!

I indeed noticed the gaps on top (and on the first layer). I don't know if I can lower the z-height of another 0.1mm though. I'm already very close to the heatbed, I'll give it a shot.

thanks again, really appreciated your help.

edit:

this would be the bottom layer.

Re: What does cause this kind of glitches (globs)?

There is also a possibility that the top layers, being very small, does not have time to cool down enough before the following layer.

You can use feature in the slicer to detect the printing time of the layer and to slowing it when the layer is too small. In Slic3r, it's in the cooling section.

Re: What does cause this kind of glitches (globs)?

You can use feature in the slicer to detect the printing time of the layer and to slowing it when the layer is too small. In Slic3r, it's in the cooling section.

that's interesting. Is it "slow down if layer print time is below"? By default it is set to 25 seconds, which seems a lot. The top circles are done in like 4-5 seconds each.

Re: What does cause this kind of glitches (globs)?

Yes it's this setting.

This value will trigger the condition, and slic3r should adjust the speed so that the layer does not goes below this duration, having a cap on the minimum print speed. So having a higher time limit than the default 5 seconds makes sense.

I already had this kind of issue on a similar part, the first version was printed with other bigger object without any issue, but printing it alone was always a mess on the upper layers. I lost a lot of hairs trying to figure out why 🙂

Re: What does cause this kind of glitches (globs)?

thanks for your reply guys. It's weird because I printed other things and I've never seen something like that.

Actually the whole model was printed correctly apart from the top part (the one pictured). I will try what you suggest, thanks!

I indeed noticed the gaps on top (and on the first layer). I don't know if I can lower the z-height of another 0.1mm though. I'm already very close to the heatbed, I'll give it a shot.

thanks again, really appreciated your help.

edit:

this would be the bottom layer.

How many top layers do you print here?

Re: What does cause this kind of glitches (globs)?

it's all by default so far. 6 top layers, 4 bottom layers.

Re: What does cause this kind of glitches (globs)?

Matteo

Both the bottom and top layers display under-extrusion, yet the blobs could contradict that assessment.

Try Christoph's suggestion first, then calibrate the filament feed before making any other adjustments.

I would usually suggest making a change to print the perimeter last, but you have a severe overhang at the bottom of the model, so that will probably not work. You may find that using a different slicer will help or changing retraction, getting rid of Z-Lift (if you have that turned on). Turn on wipe and coast.

It would maybe help to remove the bottom of the model to speed up testing (and save wasted filament) so that you can try a variety of different settings.

Peter

Re: What does cause this kind of glitches (globs)?

thanks for your help PJR

I sliced the base and the top of the model to make some tests. I used the base to optimize flow and z height and the top for the "globs" issue.

I lowered the z height by 0.040 and the result is definitely better on the base. I loose just a pinch of definition but the texture is better. I also tried the same model on both Cura and Simplify3D, to my surprise Cura ended up with the best result. I tried to keep the same settings on all software but of course there will be some small differences.

Now I'm testing the glob issue, I'll post as soon as the print is done.

Thanks again, guys. You are very welcoming community.

Re: What does cause this kind of glitches (globs)?

I think that the first layer should be completely flat though, try increase the extrusion just a tiny bit.

Re: What does cause this kind of glitches (globs)?

After a lot of testing I was able to fix most of the issues.

The blobs on the thin walls were indeed caused by hasty printing. I feel I still have some gaps both on the base and on the roof, but I'm a bit scared of pushing the extrusion too far. If I lower the z height I start loosing details, most of the times that wouldn't be an issue but with this particular model it is.

Picture above is with latest Cura beta.

thanks everybody for your help.

Re: What does cause this kind of glitches (globs)?

Hey matteo,
2 tips I can give for S3D as I use that mainly are,

In Simplify 3d you have a setting that's called "coast at end" on the extruder tab, this will stop extrusion a "set coasting distance" from the end of the loop. This helps for blobs at the end of a layer. I usually use a value between 0.2 and 0.6mm depending on material. Also retraction is important.

Also, you have a setting on the extruder tab that defines extrusion width, try the different settings to see if it helps, but do it in very small steps, deviating not to far from your nozzle width.

maybe this will help 🙂
happy printing,
Serge

Re: What does cause this kind of glitches (globs)?

thanks serge, I definitely need to play around with the slicer options.

everyone was praising S3D but so far I got the best results with Cura, but what do I know... I such a noob 🙂

I already have coast at end enabled at 0.2 but S3D automatically slows down when the layer is too fast, so I believe that's what fixed the blobs for me. I'll have a look at extrusion width too. I believe it is suggested to set it at 120% the nozzle size... well anyway I have a lot of testing to do.

Re: What does cause this kind of glitches (globs)?

The truth is that every 3D model has its own one and only best slicer. The user has just to find out which one. 😆

Re: What does cause this kind of glitches (globs)?

if only it was a bit faster (and cheaper) to make tests!

Re: What does cause this kind of glitches (globs)?

The truth is that every 3D model has its own one and only best slicer. The user has just to find out which one. 😆

This is the most insightful post in quite some time. Could not agree more! 😀

Re: What does cause this kind of glitches (globs)?

The truth is that every 3D model has its own one and only best slicer. The user has just to find out which one. 😆
I'd maybe not go that far to say that every model has it's own best slicer, but every model has definitly got it's very own fine tune settings in the slicer of your choice 🙂

have fun printing 🙂
Serge