Optimize retraction settings to prevent rework by hand after print

[Almgandhii 0]

Hey everyone,

 

I am quite new to 3D-Printing and I have some problems with filament threads in non printed areas. Attached you can find some pictures of the problem and also my travel settings. In the moment I have to put in quite some work by hand after printing, but since I will have to print hundered of those parts in the future, I want to optimize the printing as much as possible. Can I solve this problems by changing my travel settings? Or do I have to solve the problem constructively eg. by enlarging the space between parts and also changing the parts itself?

 

Let me know if I need to provide more informations.

 

Thanks a lot for the support!

[gr5 2,179]

I would turn off retract at layer change.  That caused a lot of ugliness and underextrusions for me but that's not your issue as it would only wreck one of those parts.

 

The combination of the two settings Maximum Retraction Count and Minimum Extrusion Distance Window can prevent retractions from happening if set wrong.  I think that is fine but to be sure, look at your part in PREVIEW mode and set color scheme to "Line Type" and make sure "travels" is checked.  If you do all that then you can see the travel (non printing) moves in blue.  Light blue lines are retraction moves, dark blue (solid dark blue - very blue) lines are non-retracting.  Make sure the areas where you have the stringing is light blue (meaning you have retraction).  I suspect you do.

 

Turn off z hop when retracted.  z hop causes all manner of issues if you don't have a delta printer (it sounds like this is an S5).

 

The retraction distance of 6.5mm assumes you have a normal bowden on a normal S5.  Cura has 8mm for me on my profile (nylon/pva) right now.  Maybe because nylon is springier?  I don't know.  I think these values tend to be carefully chosen but I'm not 100% sure.  You want to reduce the pressure in the nozzle without actually pulling the filament up out of the print core which would let air in the nozzle and make stringing worse.  You can listen and watch the filament at the top of the arc of the bowden tube and you should see it just rest at the bottom of the tube (what I am trying to say is more understandable if you just watch the process a few times) without pulling up out of the print head.  The retraction distance is longer if the bowden is loose - try pulling up and pushing down gently on the bowden at the feeder end and the print head to make sure it doesn't move.  If it moves up and down by 1mm then the retraction distance should be increased by 1mm or you should fix that "play".

 

Finally - I suspect the most likely problem is you aren't using PLA and are using PETG or CPE or nGen that has absorbed some water.  These materials print quite well without being dried but I'm told one issue is they string much more.  Let me know what material you are using and I can give you drying instructions - it's hard to get the drying process correct.  Most people dry at too low a temp, or they don't unspool, or they don't dry long enough, or they heat the base of the spool but where the top of the spool is 30C cooler.

 

Typically I dry at 70C (that's much too hot for pla!  It will destroy your pla) with the necessary quantity unspooled and sitting on the heated bed under the spool with a towel over it all and for about 4-12 hours.

 

And one more thing - there is an option "print one at a time" where there is less retraction but you still need retraction even on a single part so I almost didn't mention this.  It would mean printing many fewer parts at a time.

[Almgandhii 0]

Thank you so much for your reply, that helped a lot!

 

What I did not mention yet:

-My Printer is an S5 as you supposed correctly.

-I am using the standard Ultimaker tough PLA black which came with the machine.

 

That preview mode with checked travels, as you mentioned, is exactly what I was looking for!

So I checked the pathing of the machine and I saw that in the upper part of my parts it seems to not distract at all, See picture 1 (dark blue lines).

 

I played around with all the settings you mentioned but nothing seemed to help with my problem...

What finally did the trick (at least I think it did, I havent printed yet) was checking "Rectract before outer Wall".

After I checked that, my pathway looks like picture 2 which seems right to me.

 

I'll try to do some testprinting with those settings tomorrow 🙂, very curious if it will help!

 

About the "print one at a time" option, I thought about that too, but the option is just not there for me... see picture 3.

 

Again, thanks a lot 🙂 !

 

 

[gr5 2,179]

That mode is disabled unless you are only using one extruder.  You have to explicitly disable the second extruder in the PREPARE screen (which is where you also pick which filaments go with which printcores and which printer you are using and so on.

 

"one at a time" has major caveats.  If the parts are too tall they will hit the bars that go through the print head when the bed comes back up for the second part.  The print head is large so the parts have to be spaced out more than the width of the head (this is automated or at least it shows you when parts are too close).