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daniel.t5
(@daniel-t5)
Active Member
Stringing on MM

Over the weekend I upgraded my mk2S with the 4x Multi Material kit, and now I am having a real problem with stringing.

I am using the new Prusa Edition of Slic3r to slice, I've tried fiddling with temperature, didn't seem to do anything, I increased the retraction from the default in Slic3r (4) to 5, since I saw someone saying that a range of 4-5 will be required, and it did seem like it helped, but then it seemed to clog and my print failed. I had read that would probably happen, but I needed to try for myself.

I have this problem even when printing in single mode.

I did not have any issues with stringing before performing the upgrade.

Any suggestions on how I can improve this?

For what it's worth, the overall quality of my prints have seemed to go down since upgrading, but I'm trying to tackle one issue at a time.

Thanks!

Posted : 18/09/2017 5:21 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing on MM

There are a few ways to overcome stringing, the main ones being retraction and temperature.

What material are you printing and what temperatures are you using?

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 18/09/2017 6:09 pm
daniel.t5
(@daniel-t5)
Active Member
Topic starter answered:
Re: Stringing on MM

I'm printing PLA, and I've tried as low as 180, and as high as 220 and seen roughly the same amount of stringing.

Posted : 18/09/2017 7:06 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing on MM

In that case, there's another issue happening elsewhere.

Can you slice a model using E1 and E2, both PLA at 200 degrees with 4mm retraction, zip up the G-code and upload it for me to have a look at.

Thanks

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 18/09/2017 7:37 pm
ir_fuel
(@ir_fuel)
Estimable Member
Re: Stringing on MM

Same problem here, and it's independent of the used extruder. I use Slic3r Prusa MMU edition and use the default settings. Currently running a print with the Prusa grey PLA and it also has stringing, so it's not because of incompatible filament. Really hesitant to start playing around with retraction settings as I read on the forums that that can lead to blockages?

I'm just printing using 1 extruder btw. No multicolor prints right now. No use overcomplicating stuff if the basis doesn't work right.

I bought this kit not for colors but to be able to print with PVA and PLA at the same time, but I wonder if I'll manage to get this working decently ... The direct drive single extruder mk2s worked flawlessly. Seems that since I went to MMU it all went downhill. First print quality issues (other thread ...), now this.

Hopefully I can get my CR-10S first layer as good as on the Prusa, then at least I have a "quality" 3d printer that works while tinkering with this one (same filament on the CR-10S and same extruder temp gives zero stringing). Too bad the CR-10S isn't direct drive.

Posted : 18/11/2017 1:27 pm
ir_fuel
(@ir_fuel)
Estimable Member
Re: Stringing on MM

btw @PJR, amazing how much time and effort you put in this forum. I hope Prusa recognizes this and gives you some compensation for helping their customer base.

Posted : 18/11/2017 1:28 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing on MM


btw @PJR, amazing how much time and effort you put in this forum. I hope Prusa recognizes this and gives you some compensation for helping their customer base.

Thanks.

I really don't want anything from anyone - don't want to feel obliged to do this. I just with I could get some assistance from PR on occasion. 😥

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 18/11/2017 6:03 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing on MM


Same problem here, and it's independent of the used extruder. I use Slic3r Prusa MMU edition and use the default settings. Currently running a print with the Prusa grey PLA and it also has stringing, so it's not because of incompatible filament. Really hesitant to start playing around with retraction settings as I read on the forums that that can lead to blockages?

I'm just printing using 1 extruder btw. No multicolor prints right now. No use overcomplicating stuff if the basis doesn't work right.

I bought this kit not for colors but to be able to print with PVA and PLA at the same time, but I wonder if I'll manage to get this working decently ... The direct drive single extruder mk2s worked flawlessly. Seems that since I went to MMU it all went downhill. First print quality issues (other thread ...), now this.

Hopefully I can get my CR-10S first layer as good as on the Prusa, then at least I have a "quality" 3d printer that works while tinkering with this one (same filament on the CR-10S and same extruder temp gives zero stringing). Too bad the CR-10S isn't direct drive.

I have 2 Mk2/s + MMU printers. Strangely they require different filament retraction settings - one 1mm less than the other. I get blockages if I mix them up.

For me, stringing depends on temperature, retraction speed, retraction distance, layer height and filament colour/manufacturer. It really is a matter of getting everything tuned in. And maybe implementing Linear Advance which should allow retraction distance to be halved.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 18/11/2017 6:07 pm
ir_fuel
(@ir_fuel)
Estimable Member
Re: Stringing on MM

Any idea what the best way forward is to find out what's going on?

I did a PETG print with an endoscope cam installed on my printer and what I saw there was that while printing sometimes small globs of PETG would come out of the nozzle and go to the side instead of going down to the layer. Then a while later this glob either falls off or gets picked up somehow and that of course causes "dirt" in the print. This is not related to a first layer/bed level/z height issue as this also happens when printing a layer at let's say 5mm height. I tried cleaning the nozzle and hotend but it was all ok, and my next print using PLA had stringing again too.

I managed to get a bit less stringing on PETG by setting the extrusion multiplier to 0.8, but isn't that extremely low already?

Anyway, both PETG and PLA string, and with the PLA I ran the exact same spool on another printer and there it doesn't string.

Posted : 20/11/2017 12:22 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing on MM


Any idea what the best way forward is to find out what's going on?

I did a PETG print with an endoscope cam installed on my printer and what I saw there was that while printing sometimes small globs of PETG would come out of the nozzle and go to the side instead of going down to the layer. Then a while later this glob either falls off or gets picked up somehow and that of course causes "dirt" in the print. This is not related to a first layer/bed level/z height issue as this also happens when printing a layer at let's say 5mm height. I tried cleaning the nozzle and hotend but it was all ok, and my next print using PLA had stringing again too.

I managed to get a bit less stringing on PETG by setting the extrusion multiplier to 0.8, but isn't that extremely low already?

Anyway, both PETG and PLA string, and with the PLA I ran the exact same spool on another printer and there it doesn't string.

PET is more likely to blob and string than PLA; let's get PLA sorted first and then move on.

1. Install a sock (will help PET blobs)
2. Slice a model, zip up the G-code and attach to a post so I can see what is happening.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 20/11/2017 1:56 pm
ir_fuel
(@ir_fuel)
Estimable Member
Re: Stringing on MM

Well, guess what ... after doing the PETG print and the cleaning and more PETG, now back to my orange PLA.

Stringing is a lot less than before. There still are some but it's like 5% of what it used to be.

BTW what is that sock thing you talked about? Never heard of it.

Posted : 20/11/2017 5:40 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing on MM

Socks: https://e3d-online.com/v6-socks-pro-pack-of-3

These are better than the new type; they cover the nozzle so nothing sticks.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 20/11/2017 6:44 pm
ir_fuel
(@ir_fuel)
Estimable Member
Re: Stringing on MM

Thanks.

Just ordered a set.

Posted : 20/11/2017 7:24 pm
ir_fuel
(@ir_fuel)
Estimable Member
Re: Stringing on MM

I suppose playing with linear advance might also help?

Posted : 20/11/2017 11:12 pm
PJR
 PJR
(@pjr)
Moderator
Re: Stringing on MM


I suppose playing with linear advance might also help?

Theoretically it should.

Peter

Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…

Posted : 21/11/2017 10:02 am
Vojtěch Bubník
(@vojtech-bubnik)
Admin
Re: Stringing on MM

Jindra, our print expert noted: linear advance will help reduce stringing, though the linear advance values are excessive on the bowden MM setup.

Posted : 29/11/2017 8:56 pm
david.c16
(@david-c16)
Eminent Member
Re: Stringing on MM

Seems I too have started having string in MMU single extruder prints. Printing the same models as before MMU. I've tried 5 c less in temp, which didn't help. I'm wondering if the default 4 mm retraction is too much ? Seems it was only 1 mm in the pre MMU slicer. Any thoughts ? Thanks !

Posted : 30/11/2017 3:20 pm
Vojtěch Bubník
(@vojtech-bubnik)
Admin
Re: Stringing on MM

The retract value is to relieve the pressure built up in the nozzle. Due to the slack in the bowden tubes, the retract for a MM setup needs to be much higher than on a non MM setup. The slack in the bowden tubes is nothing specific to Prusa printers.

Posted : 30/11/2017 3:39 pm
mavu
 mavu
(@mavu)
Estimable Member
Re: Stringing on MM


The retract value is to relieve the pressure built up in the nozzle. Due to the slack in the bowden tubes, the retract for a MM setup needs to be much higher than on a non MM setup. The slack in the bowden tubes is nothing specific to Prusa printers.

Did you try capricorn tubes in house?
Do they actually help to reduce the needed retraction?

Posted : 01/12/2017 9:02 am
Vojtěch Bubník
(@vojtech-bubnik)
Admin
Re: Stringing on MM

I know that the capricorn tubes are on order. I am not sure whether they arrived, we are currently all busy with rolling out the MK3.

Posted : 01/12/2017 9:25 am
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