How to eliminate PETG strings?

[qiman 0]

Using Cura with a CR-10S.

 

PETG nozzle 240 and bed 75, speed 60. Nozzle is 0.4mm, which is the stock nozzle that it comes with. 

 

I enabled retraction at the suggestion of someone to eliminate the strings you see in this pic and it may have made it worse. It is just a circle with a flat flange at the bottom. 

 

Any recommendations would be greatly appreciated! 

[Smithy 1,145]

It looks like if there are not retractions at all.

Can you check if there are really retractions? Put a finger on the filament at the feeder to check if there are some movements.

 

I assume you use Cura, so take the profile of Ultimaker CPE as a basis - CPE is also PETG.

 

[fergazz 60]

you can also make a stringing test downloading an stl from thinginverse...

every time I try a new filament/material I do that test:

 

and them test different retraction distance to find the sweet spot.

In this case (picture) I'm using simplify3D slicer

 

Edit: This is PLA Polymax filament... it's probably not the ideal settings for PETG 

Edited October 15, 2018 by fergazz

[qiman 0]

5 hours ago, Smithy said:

Thanks Smithy, I copied over the retraction settings. Was that all I should have copied or all the other settings? 

Fergazz, I downloaded a small retraction test tower and the pic attached shows the results. That was when I copied over the CPE retraction settings. 

I then printed more rings. the 4 inside the border are the ones with the new settings - still stringy but not as bad as the ones you see at the very top so there is progress! I did confirm that I did have retraction set before and the gear was definitely pulling the filament backwards. You can also see the heat, speed and fan settings in the other image. 

For the next print, I'm changing the CPE copied settings to 9mm retraction distance, 40 mm/s retraction speed and I lowered the filament temp to 230. I also sped it up to 70% instead of 60%. Is that the right idea or should I try something else? Seems it is an art form to perfect the petg anti-stringing settings. 

 

 

[fergazz 60]

 

Quote

 

Great, there is a progress here, definitly... but it can be improved a bit more. 

PETG is a stringing material and this fine tune is necessary sometimes... 

 

How was the profile for those prints... the same? In Cura I saw the Ultimaker profile for CPE showing: 240, 70°C (for bed), 6,50mm (retraction distance)... but maybe for CR-10S the profile is a bit different. I f you go to Preferences > Settings > Material you can mark retraction distance and change the value on the main menu.

 

there are some tricks to avoid stringing, try to tweek but don't do some radical changes... you can reduce it with a combination of settings or modifing one of those:

- lower temperature a bit, like 2 to 4 degrees;

- increase travel speed a bit (about 10mm/s) I believe it's more usefull than increase the retraction speed;

- and tweek retraction distance... bowden tube of Creality printers are smaller than Ultimaker (UM2 is around 70cm) it uses smaller retraction distance. At least Ender 3 printer have around 4,50mm to 5,5mm for PLA instead of 6mm. But since this stringing test is a small piece and prints really fast you can try around the distance setted in your test. It will probably be closer to that number... alter like 0,5mm or 1.0mm maximum. 

 

Keep showing your results for us ? 

Edited October 16, 2018 by fergazz