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PLA woes (stringing)

Posted: Mon Jun 26, 2017 3:26 pm
by ExplodedZombie
I finally got my printer printing. ABS is just okay, but PLA is stringy as junk. I have tried a ton of settings and variations based on all the guides I could find on the internet. Always pretty close to the same results:

Rostock Max v2 with E3D v6 (new version)
Temp: Tried 180 - 200
Move non-print: 225
Retract: tried 2mm - 5mm
Retract speed: tried 30 - 60
Filament: Hatchbox black pla, Gizmodorks purple pla (both same results)

Some funniness: Everywhere I see mention of low retracts, low retract speed, low temps, etc. Lower temps seem to make it break off slower = more stringing. Lower retracts and lower speeds seem to do the same. Anyone have any other ideas I can look at?

I also tried other models. Some with less stringing but still there when moving long distances.

Results: ... g.html?o=0

It won't let me embed this image...I'll try to fix later.

Re: PLA woes (stringing)

Posted: Mon Jun 26, 2017 6:27 pm
by joe
Judging from the photo I would say you are over-extruding. That means your extruder is forcing too much plastic through the nozzle so yes it will string like crazy with PLA.
Pull the bowden tube out of the hotend. Trim off the pla filament flush with the end of the loose bowden tube and advance 100 mm of filament using repetier host or whatever slicer you are using. Then measure to see how much filament came out. Should be exactly 100 mm.
Also make sure your slicer is setup with correct nozzle diameter.

Give that a try.

Re: PLA woes (stringing)

Posted: Wed Jul 12, 2017 5:52 pm
by ExplodedZombie
Thanks for that advice! I was over-extruding by a tiny bit. Fixed it! Unfortunately that didn't fix the problem.
This time I did
Temp: 200
Slicer: MatterSlice (Cura just fails to slice it)
Move non-print: 200
Retract: 4mm (2.5mm had same results)
Retract Speed: 100mm/s (I just don't see any difference no matter retract settings)
Filament: Gizmodorks purple pla
Minimum Retract distance: 5mm I think.

Mostly it's super whispy strings, but every now and then there is an extra blob, especially in the trunk.

Re: PLA woes (stringing)

Posted: Wed Jul 12, 2017 6:33 pm
by Tincho85
Why 100mm/s? I would be one of those to recommend to go slow. It's much safer and it practically doesn't affect printing time.

It looks like it's a small print, with small islands very close to each other. If your minimum retract distance is set to 5mm, then I bet retracts are not beign triggered at all.

If that doesn't fix it:
* did you try with a different PLA color/brand?
* wipe nozzle during retracts.

out of ideas for now.
You could check Simplify 3d troubleshooting guide, it has a lot of info.

Re: PLA woes (stringing)

Posted: Wed Jul 12, 2017 10:54 pm
by Doug68
The minimum retract distance at 5mm means it'll have to print 5mm before it even attempts a retract, you can try making this distance much smaller 1mm or even less.
Also I see no mention of Z lift about 5mm of that can snap the string before it gets dragged over the part.
Also make sure there's no slop in the bowden arrangement or you movement on that will need to be bigger to account for the slop.

Re: PLA woes (stringing)

Posted: Wed Jul 12, 2017 11:10 pm
by Tincho85
Doug68 wrote:The minimum retract distance at 5mm means it'll have to print 5mm before it even attempts a retract, you can try making this distance much smaller 1mm or even less.

I belive is determined by the distance from "point A" to "point B" and not by how much it has been printed.
But yes, lower that value and see how it goes.

Re: PLA woes (stringing)

Posted: Wed Jul 12, 2017 11:29 pm
by ExplodedZombie
Oh derp!

Yes that makes sense, the 5mm minimum distance. I've never tried Wipe before retract, though it doesn't have that option in MatterControl if you use CuraEngine, I think. Will try that stuf.

Z lift was set to .5 because I read in another post on another site that a high lift adds time between printing which means more oozing. Dang I have got this all backwards.

Re: PLA woes (stringing)

Posted: Thu Jul 13, 2017 12:51 pm
by ExplodedZombie
Again, THANK YOU! I really need to take the time to learn what each setting REALLY means. Not just understand the tooltip. I set the min distance to 1, speed to 40, retract dist to 2.5 (recommended by E3d, may up a bit for test), and z-lift to 2 (to start).

Wow. Seriously. There are almost no strings. There is a little bit of oozey drip between the trunk blades, but I think lowering the retract dist a little more might fix that. I dunno but this is an amazingly good place to start..

I wish I could buy you all beers. Heck, the whole helpful community :) Let me know if you are in the Bay Area and I'll do it!