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."
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.
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?
Printed on Cura LE 3.6.21 Polylite PLA with firmware 220.127.116.11. 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.
@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.
@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.
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.
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.
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.
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.
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.
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!
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! 😄