zerofear
Posts: 4
Joined: Thu Dec 06, 2018 10:29 pm

Extrusion Skipped Blips

Fri Nov 27, 2020 3:32 pm

I honestly don't how to describe these little issues. It is like my printer is under extrusion, but only for a couple of mm only on outer layers. Very random. Some prints will have a few of these "pok" marks as I call them, others will have a bunch. Sometimes only a few. In the picture here, they are a little more bunched up on this model. Usually that are pretty spaced out.

Doesn't matter if it is a new spool. I have cleaned and even put a new hot end on. No difference. I have tried playing around with e-steps and extrusion multiplier. Sometimes it seems like there is are less, but then I print and then a new model has a bunch of them.

One thing I will say is I only seem to have these marks on my two printers that are direct drive. Is there a settings I am missing somewhere? Is there something hardware I am missing?

These printers were not originally direct drive. I upgraded them using MicroSwiss direct drive kits. Only started happening after the upgrade. So I am thinking it is a setting I am not used to for a direct drive, but not sure. (Creality CR-10 and Creality Ender-5)

Thoughts? Ideas? Is there something I can adjust in Simplify3D?
marks2.jpg
marks1.jpg

User avatar
dkightley
Posts: 2300
Joined: Tue Mar 10, 2015 4:09 pm

Re: Extrusion Skipped Blips

Fri Nov 27, 2020 5:14 pm

This is where getting to know how the slicer works is quite useful!!!!

Your printer looks as if it is either stopping extruding too soon before the end of a layer....or it is not starting to extrude as soon as it should at the start of a layer.

Knowing how the slicer works, you will instantly realise that this is something to do with the ooze control settings. The extrusion stopping early is controlled by the Coast setting...the greater the coast, the earlier the extrusion stops. The late start is a tiny bit trickier..it'll be a combination of the four Retraction settings.

Read this page to see what each setting does: viewtopic.php?f=8&t=1980

What you need to do first....is to watch the extruder in action and work out iwhich issue you have....excessive coast or excessive retraction.
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net

parallyze
Posts: 226
Joined: Fri Jun 05, 2015 4:18 am

Re: Extrusion Skipped Blips

Fri Nov 27, 2020 6:06 pm

Hi,
zerofear wrote:
Fri Nov 27, 2020 3:32 pm
... for a direct drive, but not sure. (Creality CR-10 and Creality Ender-5)
out of curiosity, did you adjust the retraction distance? I don't own one of the mentioned printers but remember they're using
pretty high values (~3-4mm) sometimes in their profiles.

That might be way too much for a micro swiss - so you end up pulling the filament too far, right out of the hot zone. Something
in the range of 0.8-1.6mm might be more appropiate (depending on other settings).

zerofear
Posts: 4
Joined: Thu Dec 06, 2018 10:29 pm

Re: Extrusion Skipped Blips

Fri Nov 27, 2020 10:49 pm

Yes, I have made all the retraction settings recommended by MicroSwiss. Actually been printing with the MicroSwiss hot end for awhile. Just recently upgraded to the DirectDrive. Retraction is 1.5mm. Retraction speed is 35mm. No coast, and no wipe. I am printing now, I tried making some adjustments. I dropped retraction to 1.0mm. Trying not to make too many changes at once so I know what fixes it. Will see what happens. I will play around with coast and wipe.

Just seems weird that it is not consistent. I would think if it was one of those settings, I would see it on every layer, not sometimes 100s of layers between the issue happening. In the pictures I showed, it happed quite a lot. In the rest of the figure, it is still there, but rare.

Thank for the info.

parallyze
Posts: 226
Joined: Fri Jun 05, 2015 4:18 am

Re: Extrusion Skipped Blips

Sat Nov 28, 2020 7:18 am

zerofear wrote:
Fri Nov 27, 2020 10:49 pm
Just seems weird that it is not consistent. I would think if it was one of those settings, I would see it on every layer, not sometimes 100s of layers between the issue happening. In the pictures I showed, it happed quite a lot. In the rest of the figure, it is still there, but rare.
Aaah... okay. The pictures are quite misleading then, I just tried to see if it was spread across layers and couldn't see any defects
on the same layer. And as there's almost no layers without those "missing parts" retracts ended up as suspect #1... :)

The set seems to come without a stepper, so you're using the old one and didn't have to do any vref adjustments?
Does the problem occur more often in a certain area of the print bed, is there anything (guide tubes) which might add friction to the filament before it enters the extruder?
Spring tension, did you check that one?

If there's a bit of filament missing when there's no retracts it might be extruder "skipping", this usually can be seen and heard pretty well
when near the machine. Or it might be filament slipping because of not enough tension on the spring - hard to tell on the distance ^^

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