Stringing issue that just started recently

[opy01 0]

I got an Anet A8 about 6 weeks ago and after tuning it I was quite happy with the prints.  But you know how it is, you're never happy enough for long.  I wanted better prints and more reliable and easier to use stuff so I converted to a bowden setup moving my stepper off the carriage and making it as light as possible for speed and quality.  For a while my prints were turning out incredible with minor strings and little cleanup.  Lately though, after installing Marlin and a bed level sensor and upgrading to Cura 3.2, I noticed all my print jobs had more and more string.  I've also been using different filament.  One thing I noticed was if I did not print in the 210-220 range my nozzle clogged.  I removed it and cleaned it thoroughly and even added a tiny bit of oil to it to make it extrude better.  The strings started way before this though so I know the oil is not my issues.

 

This is what I've done and noticed.  The higher the temps, the less I can retract as it cools further up and gets stuck.  I'm using hatchbox black 1.75 mm PLA that is actually closer to 1.7 mm for my string test.  I've put the diameter in Cura too.  I went from 120 mm/s travel speed, 2 mm retract at 50 mm/s and 210 degrees to 200 mm/s travel speed, 3.25 mm retract at 70 mm/s and 190 degrees with little to no difference in stringing.  My final test was at 190 degrees and 3.5 mm retract and it looks exactly like all the other tests.  I tried going to 4 and 5 mm retract but it just clogged my nozzle.  Good thing I was right there to unclog it quick or it may have been more difficult. When I first got this and did the string test I could make a small change in Cura 15 and actually notice a difference.

 

Is Cura not sending all my retract settings or is my bowden setup not allowing it to retract good enough (possibly pressure in the tube uses most of the retract to relax before retracting) or is my nozzle jacked up or can my firmware be interfering?  I'm actually very confused why I cannot get any improvement at all.

[mattgriffin 28]

there are a couple of places to check, but i have a quick (if not cheap) thing you should start with -- keep those settings and grab some better filament than that Hatchbox. I'm not saying hatchbox is bad, but i think you should look at two similar filaments from different vendors and see if you get similar results. And then drop the temperature 5degrees or so and try again.

 

How firmly is your bowden clamped on both ends? If there is play, well, that is not good. ;-)

[opy01 0]

It was doing this with Ziro filament too.  I can’t remember if the Bamtack did this too, but it used to not.

 

i will definitely check the tube.  I didn’t even think about that.

 

thanks.

[opy01 0]

The tube is fine on both ends, very tight.

[93levya 0]

When I started using 3.1, and later 3.2, I started having similar issues, I had very little stringing problems beforehand, and with each updated version of cura it seems to get worse. I use a Prusa mk2, recently replaced my nozzle and whatnot (after the issue started). I have a whole bunch of old g code files to print, which have no issues. It only occurs on new ones.

[opy01 0]

@93levya my extruder motor mound cracked and was not putting enough pressure on the filament so it was not retracting like it should’ve.  I clamped it down and it’s working great till I print and improved mount.

 

thanks everyone for their feedback.  Everything noted here has helped me and will hopefully help others.