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PLA Stringing
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I'm not sure what's going on here but we're getting reports of a lot of stringing with PLA filaments. The pictures below were posted to the LulzBot facebook group and I was contacted by 3D printing industry this morning saying "We are still getting the stringing when using the PLA settings. We have tried with the filaments provided as well as with 3rd party ones. When printing with PETG, the prints come out great with no strings at all so we are a little confused as to why the PLA is stinging so badly."

Event Timeline

karrad reassigned this task from adam to anolen.Aug 28 2019, 3:43 PM
karrad added a project: Cura LulzBot Edition.
karrad triaged this task as High priority.
karrad added subscribers: anolen, gyukish, lisa and 5 others.

@anolen We have had this reported on the facebook group and by one reviewer. Please look into this one as a high priority.

bmh added a subscriber: bmh.Aug 29 2019, 11:57 AM
lisa added a comment.Aug 29 2019, 3:44 PM

Have a fidget spinner printed on the workhorse today showing this issue.

karrad moved this task from Backlog to Profiles on the Cura LulzBot Edition board.Aug 30 2019, 8:04 AM
anolen added a comment.Sep 9 2019, 7:59 AM

Please Update your Cura and try using Polymaker PLA with the updated profiles. Thank you all for your feedback. Pictures, material maker and type, and cura version are very helpful information for me to properly address these issues.

karrad lowered the priority of this task from High to Low.Sep 13 2019, 3:20 PM

Dropping priority on this, please post feedback from Cura 3.6.20 or newer

I'm noticing something strange involving the stringing problem, so I figured I would post here about it. I've been seeing problems with the stringing on the workhorse at my desk, so I tried loading an older file that was sliced before this stringing problem started to arise. With my older slice it did not have the stringing problem in the past, however now it does. I'm wondering if something in the firmware could have possibly changed that could be leading to the stringing?

@bigmansas Print the same gcode file on different versions of firmware and compare the results.

Along those lines, check each gcode file. In the top line there should be a comment referring which versions they were sliced with. Please post that here

lisa added a comment.Sep 20 2019, 10:24 AM

This is a high priority. Still seeing reports from the field. Social media posts state that customers are frustrated and taking about returns.

alexei raised the priority of this task from Low to High.Sep 20 2019, 10:55 AM
alexei changed the edit policy from "All Users" to "Cura LulzBot Edition (Project)".
alexei added a project: Marlin.
alexei added a subscriber: alexei.Sep 20 2019, 11:00 AM

@bigmansas , @karrad, @anolen : Rised the priority as per @lisa request. The main question I have is weither or not stringing is happening with CuraLE 3.6.20.

@lisa We need information from these reports. What specific material they are using (manufacturer and type), quality setting, and version of Cura. Who from your team can reach out and get this information?

Printed on 3.6.18, Polylite PLA standard settings, polylite PLA:

Printed on Cura LE 3.6.21 Polylite PLA with firmware This was sliced with the latest version of Cura as well. The stringing isn't as bad as I've seen, but still kinda poor looking.

@bigmansas what quality setting?

Standard, with everything else default.

logan added a subscriber: logan.Sep 24 2019, 8:24 AM

@karrad and I worked together to figure out a solution, this profile includes both our findings/fixs, please test and report back in this ticket.

@bigmansas Please load this profile in and verify with your model you posted above

@karrad I have the profile downloaded and will be able to give it a go tomorrow. I've got some jigs going for production on the Workhorse on my desk for most of the night tonight. Also, I found the old .gcode that we were talking about that did not have the stringing problem. It was sliced on 08/20/19.

My first test print with the new profile on the fossil fish stripped out early on. I'm setting up a second go with it now.

My second attempt stripped out at the hobbed bolt as well.

@bigmansas can you reduce the retraction speed by 5mm/s on your profile and try again?

@anolen It is still stripping out with the retraction speed reduced to 15mm/s.

@bigmansas What is your workstation name? I would like to install 3.6.18 on your computer, and see if you can duplicate your successful result posted earlier.

I have a print going that is a similar model to what you are printing @bigmansas, its at 50% with no strip out issues. Ill let you know if it happens, do you have another tool head/machine you could compare on?

just a note that you should check all settings on the old version, importing a profile made on .21 into .18 might not result in the same profile.

@anolen I have another machine under my desk that I can set up, for comparison.

@bigmansas cool, I'm going to set a second one up here too. My t-Rex finished without a strip out. I'm going to try a bigger print for the next two.

@bigmansas We have installed 3.6.18 on your computer, please try to duplicate your above results. You will need to close Cura LE, clear cache, and restart.

Clear cache command for terminal:

rm -rf ~/.cache/cura-lulzbot ~/.config/cura-lulzbot ~/.local/share/cura-lulzbot

@karrad Working on that now. Also looking for a different test file to use, after what was discussed in our meeting.

@karrad and @bigmansas, I got a repeat of strip out and I got stringing to occur with the new profile, the only change I made was switching PLA colors from opaque orange to translucent red and the difference was big. I am going to work up something with this red and then confirm that is still works with the orange and let ya'll know.

This comment was removed by anolen.

I grabbed a different toolhead for one of the workhorses at my desk and did not have the strip out problems with the newest profile, and Cura LE .18. Here is a picture of 2 prints, one with the default Polylite PLA profile and one with the latest profile for testing. The one on the left was default, with excessive stringing. The model on the right was @anolen 's latest profile update, but on Cura LE .18. You can see the stringing has been reduced with the latest profile, however it is still there sadly. I meant to update this ticket earlier with this information, but code was down.

@cmerot and I were just having a chat about this problem, and he gave me the okay to order a couple larger heat sink fans to try using them, to help cool the heatsink and prevent heat creep from happening. On my machine at home I have been running the hardened nozzle and hobbed bolt for over a year, with a larger heatsink cooling fan and it has completely eliminated heat creep from happening. The only time I get strip outs now, is when my tensioner is to tight. With a larger heat sink fan, we should be able to bump up retraction distances and also temperature without the strip outs happening, in theory.

After making some measurements a 40 x 40 x 20mm fan will not fit on the Taz Workhorse, due to the endstop at the x-motor having a less than 20mm gap between the motor and heatsink fan.

tutley added a subscriber: tutley.Sep 26 2019, 10:00 AM

@bigmansas the issue is not heat creep related. If that were the case we would be seeing jammed tool heads. the issue is related to retraction, print temp and print speed, as well as material variances across different PLA colors

@cmerot @bigmansas I am not sure it would be a good use of time or money to order those fans at the moment.

@DaniAO Sage and diplomatic advice. Thank you.

bigmansas added a comment.EditedSep 26 2019, 3:20 PM

Here are some pictures of 3 profile changes I tried making to the latest profile that was on this ticket, as well as small spreadsheet on data gathered/changes made. It looks like reducing the retraction distance to 2mm and increasing the retraction speed to 25mm/s helped reduce some of the stringing between open areas, however it did leave some wisps of filament on the top layers.

Here is the profile, in case anyone wanted to give it a try.

Here's the data.

logan added a comment.Sep 26 2019, 3:26 PM

That last one looks like it would be good if Z-Hop on retract were turned off. It should be off by default...

I've got one going right now with z-hop turned off. Will post results.

@bigmansas is this all made from the older cura and older profiles?

@anolen This is your latest profile on this ticket, loaded into Cura LE 3.6.18.

lisa added a subscriber: Grant.Oct 1 2019, 9:40 AM

I am wondering if the issue is caused by the thermistor in the hotend not being properly controlled. Since temp is on a curve this could explain why it is not an issue for petg. Are all of the hotends on the toolheads from the same batch. If not, have we tried hotends from different production batches? As you all know metals all dissipate heat differently and it is harder to control the temperature on hardened steel. We may also want to try sticking a thermocouple on the end of the nozzle to measure the temperature separately. We may also want to check the servo for proper and consistent speed. All of this will allow us to determine a standard deviation to nail the problem down if it is related to the toolhead itself and not the profile.

@Grant @karrad as discussed

bigmansas added a comment.EditedOct 2 2019, 7:39 AM

I set up a SE toolhead on one of the workhorses at my desk yesterday and ran the default Polylite PLA material profile, with Standard layer height and this was the result.

One thing I have been noticing while helping test profiles, is that the workhorse on my desk that has not had the hotend replaced recently, seems to get less stringing than the one that I replaced the hotend on last week. I'm not sure what could cause this, but I figured I'd bring it up here. I have been using the same SD card between the 2 machines, so it should be the same gcode, getting different results.

This was with Cura LE 3.6.20

I have concluded my PLA Taz Workhorse Standard Updates for the Stringing issue. All who can help test this profile would be very helpful.

Here is the standard profile, please import into 3.6.20 or newer.

Here is the location of my test sample images.

karrad reassigned this task from anolen to lisa.EditedOct 2 2019, 11:30 AM
karrad raised the priority of this task from High to Unbreak Now!.
karrad added a subscriber: Megan.

@lisa @Megan @dale @eBeardslee We need all Workhorse printers testing this profile with Polylite PLA for feedback. Please have your teams begin testing and post feedback on this ticket.

We've got 5 workhorses in MER getting started with the latest profile.

anolen added a comment.Oct 2 2019, 3:01 PM

After some further testing with @karrad, we discovered one edit that needed to be added. Here is the profile to be testing. Thank you!

karrad added a subscriber: jspreitzer.EditedOct 3 2019, 11:02 AM

Please print this on 3 of the workhorses currently set up in calibration using Anolens latest profile loaded into 3.6.20

Please scale the full model to 50%, I will have filament down to you shortly.

bigmansas added a comment.EditedOct 3 2019, 4:05 PM

Here are some pictures of the test prints I have done over in tech support so far. I currently have the default profile print running as a comparison.

.44 firmware

.49 firmware

Default PolyLite PLA profile on .49 firmware

I had a customer who was looking to resolve some print quality concerns on his workhorse so I sent him the most recent profile which worked great for him :) He was wondering if we happened to have a High Detail iteration of this Profile available yet so I told him I would ask.
@anolen Do you happen to have a High Detail version of your most recent profile created yet? Or settings for it that I could input into Cura and Export for the customer. I told him that I wasn't sure if we would or not so if not it's not a big deal. Thanks!

anolen added a comment.Oct 7 2019, 7:42 AM

@Galadriel, I do! I am confirming the high detail settings today (the print is long), as soon as it is done I am posting the profiles (high speed, standard, and high detail) and staging them to be merged into Cura as soon as possible 😄

@anolen You rock! Thanks for the follow up :) I will keep an eye out for the Profiles so I can send that along.

anolen added a comment.Oct 7 2019, 2:09 PM

Here are completed importable profiles, please make sure it is being imported into a 3.6.20 or newer version of Cura.

These setting changes will be merged into Cura soon so this is only for those who need it NOW! 😄

anolen added a comment.Oct 7 2019, 3:55 PM

@karrad and @alexei, Changes have been pushed and are ready to be merged into cura

alexei closed this task as Resolved.

@anolen, merged it to master.