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What should I tweak to avoid this extra extrusion at edges?

Posted: Wed Jun 22, 2016 5:35 pm
by 2CNK
This is using the stock N2 settings for high quality (0.1mm layer height) using the Raise3D PLA that came with the printer.

the sharp borders around the "face" all have some extra material, like the zits on the bottom (under the left eye in the photo) or like a fuzzy "eyebrow" over the eye. These should be smooth sharp edges.

Image

The only other defect is the little keychain loop at the top, which looks a little melty/over extruded:
Image

But the rest of the model looks OK.


Looking at the troubleshooting guide at https://www.simplify3d.com/support/print-quality-troubleshooting/#blobs-and-zits suggests that adjusting the Extra Restart Amount and/or "Coasting". I can find Extra Restart Amount in ideaMaker, but is there an equivalent for Coasting?

edit: On observing another print, the nozzle is not stopping or starting at those positions so it sounds like coasting or extra restart should not affect that.


Any other directions to look in are welcome, too.

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Wed Jun 22, 2016 6:01 pm
by 2CNK
I did another print that I stopped half way through, and I see what looks like over-extrusion also on the inside.

Image
Image

What should I look at adjusting to correct this?

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Thu Jun 23, 2016 8:01 am
by Vicky@Raise3D
That should be ooze, you can increase the Retract Material Amount and Retract Speed in Ooze tab in ideaMaker. The strings inside is also the same ooze problem.
The top defect is drooping due to gravity because it is hanging in the air without any support. It is a common problem of FFF printer. The only fix way is add support. But your print is so small, adding support may cause other problem.

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Thu Jun 23, 2016 4:54 pm
by 2CNK
Thank you for the suggestion, I will play with those settings.

I noticed something while doing this.

Interesting result from increasing retraction amount (from 1.0mm to 3.0mm) and speed (from 20mm/s to 40mm/s) is I got grinding filament and some air printing.

But curiously the filament does not appear to have been "chewed away" by the extrusion gear. Inspecting the filament I can see the white "grinding" does not seem to be from the extrusion gear, because the white abraded area on the filament is behind the extrusion gear teeth marks.

Very interesting. Maybe there is a sharp area in my extruder body that the filament rubs on, and I notice it with the increased retraction settings?

Here is a photo of the stopped print. You can see it did not print for long. Stopped because of air printing and visible filament dust in the extruder head.
Image

In that print time, here is the filament dust that accumulated:
Image

Here is the filament section that was in the head:
Front
Image

Front/side
Image

Rear
ImageImage

It appears that the abrading of the filament is happening on the side opposite of the extruder gear. I would have expected that the gear was grinding the filament, but that does not seem to be the case. Maybe there is a sharp edge in the body of my extruder that is doing this, and it's most visible with a lot of retractions.

Side note: these photos are from just this last test but I have cleaned filament dust out of my extruder head probably 4 times total so far since starting with my printer. It just.... seems to accumulate.

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Thu Jun 23, 2016 5:11 pm
by socke
From my experience with the stock extruder, I would recommend you to not use a retract of more than 2 mm (1.5 mm worked for me with R3D PLA). Otherwise, you have an increased probability for airprints.
Btw., you should really consider using the Bondtech extruder ...

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Thu Jun 23, 2016 5:42 pm
by 2CNK
It just so happens I am at this moment trying a print with it at 1.5mm retract (halved the experimental 3.0) and it's doing better than last time - it passed the point it failed at previously, anyway. Fingers crossed.

I'll look into bondtech, but after all the dough I dropped on my N2 I'm afraid my piggy bank is wiped out :!:

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Thu Jun 23, 2016 8:42 pm
by 2CNK
No real improvement in the end result, still zits at the edges, and in roughly the same amount.

I've solved the little bit of stringing and the droop with some extra cooling via a small external fan I position to blow on the print, but the zit problem remains.

I'm keeping a big spreadsheet record of what I've tried + results but there doesn't seem to be any magic bullet yet.

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Thu Jun 23, 2016 9:12 pm
by AR_LA
I had a similar issue and my best results came from increasing retraction speed to about 45, and leaving length at 1. increasing length even to 1.2 with the increase speed didn't give me better results, that was with polymax.

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Fri Jun 24, 2016 4:04 pm
by 2CNK
Thanks, I'll see if that helps for me.

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Tue Jun 28, 2016 5:17 pm
by 2CNK
For anyone who might be reading and finding it useful, here's what I settled on.

After a lot of testing and tweaking, I decided that some zits (at the sharp corners of some facial areas) were unavoidable on such a small model and with a 0.4 nozzle.

I settled on getting results that looked like this (before removing zits)

before.jpg


And after removing zits (they came off fairly easily)

after.jpg


I think this is the best I can really get on such a small item (2.5cm tall) and 0.1mm with the N2's 0.4mm nozzle.

This is using Raise3D's PLA.

I copied the High Quality profile in ideamaker, copied it to a new custom profile, and modified the following:
* Bed temp to 60C (I had troubles with models popping off the bed at 40C)
* Retract speed change from 20mm/s -> 40mm/s
* Retract Extra Restart -0.02mm (note the minus sign: -0.05mm works but it's too much, you get really sparse infill. -0.1mm gets air prints.)

I printed 3 models on one big raft, chose the best looking one. Printing 3 models gives the tiny things time to cool more between nozzle passes.

I preheated the bed manually for 10 mins or so at 60C before firing up the print (otherwise the bed doesn't have time to warm through - the heater is at target temp but the bed itself isn't.)

I manually adjusted extrusion temperature up to 215C during the raft printing, dropped it back down to target 205C after raft was done. The raft uses a lot of plastic in constant flow, and at 205C or lower the extruder can "click" sometimes when trying to keep up.

I played a lot with extra fan, lower printing temperatures, different retract settings, etc. I never got any improvement I would consider super significant. The best and simplest results for me so far seem to be the above for printing this particular model.

Re: What should I tweak to avoid this extra extrusion at edges?

Posted: Wed Jun 02, 2021 7:57 pm
by lt72884
i know this is a super old post, but i found a solution with my direct drive and bowden setups to reduce the blobs. Set line width or extrusion width to 0.35 or 0.3mm