Weird issue, over extruding in certain areas??

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JonathanB
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Weird issue, over extruding in certain areas??

Post by JonathanB » Tue May 17, 2016 11:30 am

Hey, just want to throw this out there to see what you guys think. So I've been printing for about 2 years now, I've printed small stuff, large stuff, simple stuff, complicated stuff, probably over a few hundred hours of printing so far so I've seen many issues come and go, but this is a new one for me. I have a medium sized tall part I'm trying to print and for some reason, one of the thin walled sections keep overextruding and roughing up, most of the time if a section roughs up like this I give it a chance to smooth out over the layers but this is just too extreme, I've watched the printer and it's like it lays down too much plastic in that area (refer to picture). My specs are as follows:

- Taz4, printing on PEI, have printed many parts without issues with the standard gcode values output by slic3r just prior to this part so not hardware issue. PLUS the rest of the part prints perfectly, it's just that section which is the weirdest part.

- Nozzle .4mm, LH 1.5mm, print speed 100mms, original Extrusion widths that slic3r generated seemed really large, .68 up to .87mm. Extrusion flow rate is dialed in, 40mm extruded is 40mm of filament.
Material is red ABS, I use a Hotbox enclosure.

- You'll notice in the picture I've tried a few times with roughly the same results, the one in behind was cut a little smaller just to test the area so it wouldn't take too much time to print, apparently it came out ok???????wtf.

I actually did end up getting the part to print ok but I'm still trying to figure out why this happened to begin with. My corrections were as follows:
I originally had the part laying across X, I changed the orientation to print along Y, I dropped the hotend temp to 230 from 235 but not sure if that was the issue as I printed MANY parts at 235 without issues and in all sorts of orentation. I also changed the extrusion widths down to .5 mm(20% larger than nozzle) in the gcode output file.

I basically know what I'm doing with 3Dprinting, but this one I can't quite figure out......any thoughts?
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JonathanB
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Re: Weird issue, over extruding in certain areas??

Post by JonathanB » Tue May 17, 2016 10:44 pm

Seriously? no one? that's awesome. ;)

kcchen_00
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Re: Weird issue, over extruding in certain areas??

Post by kcchen_00 » Tue May 17, 2016 11:43 pm

Hmm... never seen that before. The wispy extrusion looks to me more like underextrusion, nozzle starved of filament or issues with the model resulting in bad gcode. Originally I was going to say it looks like stuck filament on the spool, but can't explain why its only on that internal face and all the other walls look good.

If orientation was the fix, then I'd chalk it up to a quirk in slicing. Could try to go back to original orientation and re-slice.

Not familiar with Hatchbox ABS, but 230C sounds a bit low... and. .68 to .86 flow multiplier seems really low. Could be that the infill perimeter is printing at a higher speed and slicer not compensating...


If you have the gcode, I can run it through S3D's print preview/simulator...

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JonathanB
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Re: Weird issue, over extruding in certain areas??

Post by JonathanB » Thu May 26, 2016 10:58 pm

Thanks, all good points, I really think it was a weird gcode anomaly, I can print the raw output gcode files with almost any part and they output really large extrusion widths for low layer heights, the parts print without issues. So again, this seems like a weird fluke. This fluke part seemed to like the 230c, I have no problem printing anything that low of temp, it's default temp for abs in pronter :)....

Can't give you file, working on proprietary things..... finally got it to work anyway so no big deal... just going to keep an eye on it see if it happens again. Thanks for feedback though...

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JonathanB
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Re: Weird issue, over extruding in certain areas??

Post by JonathanB » Sat Jun 11, 2016 8:56 pm

Just as a little update to my issue, here was the problem, basically Slic3r 1.2.9 is garbage for thin walls..... and what do you know, this all started when I upgraded to 1.2.9 :)......

Here is a thread on the issue..

https://github.com/alexrj/Slic3r/issues/2960

Until this bug is fixed with the latest version, I'll be going back to 1.1.7, maybe 1.2.7

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