UMO Stringing Problems

[hyycam 0]

So I've been plagued by the spiderweb-y style stringing for a while now and I've tried everything suggested that's posted online to no avail. I've tried all sorts of temperatures and speeds and combinations thereof, but it keeps happening. The retraction is definitely on as well, it just doesn't seem to be stopping the stringing. What's also frustrating is that even when I have it under-extruding on the print, the stringing still happens. At this point, I am wondering if its a hardware issue that I haven't thought of? Any suggestions would be appreciated!

[Dim3nsioneer 557]

Did you go down all the way down with Temperature to the region where underextrusion begins? I would be a bit surprised if a really lower Temperature would not improve the situation.

You can also try to increase retract speed and length a bit.

[tommyph1208 55]

Other things, apart from print temperature, that affects stringing:

- Retraction speed( higher speed = faster removal of material from the nozzle = less stringing, but too fast and your feeder may skip or grind)

- Retraction distance (higher distance = less stringing, as material is retractet further away from the nozzle, but too far may result in hotend clogs and or underextrusion when extrusion has to resume after a retraction/travel move)

- Print cooling (better cooling = faster solidification of extruded material = less stringing and overall better print quality)

- Travel speed (faster travel speeds = less tilme for material to exit the nozzle during the travel, = less stringing, but too fast and your machine may skip steps on the axis)

- Print speed and layer height (lower speeds and layer height reduces pressure in the hotend melt chamber = less stringing)

[hyycam 0]

Other things, apart from print temperature, that affects stringing:

- Retraction speed( higher speed = faster removal of material from the nozzle = less stringing, but too fast and your feeder may skip or grind)

- Retraction distance (higher distance = less stringing, as material is retractet further away from the nozzle, but too far may result in hotend clogs and or underextrusion when extrusion has to resume after a retraction/travel move)

- Print cooling (better cooling = faster solidification of extruded material = less stringing and overall better print quality)

- Travel speed (faster travel speeds = less tilme for material to exit the nozzle during the travel, = less stringing, but too fast and your machine may skip steps on the axis)

- Print speed and layer height (lower speeds and layer height reduces pressure in the hotend melt chamber = less stringing)

I have tried tinkering with the retraction speed but it doesn't seem to help. Do you know what is a good range of numbers to experiment with? I was trying not to go too high but I guess I'm not sure what too high actually is.

As for print cooling, my fan speed is already as high as it gets. I've tried pushing the temperature and speeds as low as I could get them but then it starts underextruding and it continues to string as it's underextruding!

[tommyph1208 55]

It depends on a lot of things I believe... Your hotend looks like the stock one, what about your feeder?

I ran 4,5 mm retraction at 60 mm/s retraction speed for a long time I think, but can’t really remember... I switched to E3D hotends long ago...

Try playing around with the travel speed as well...

Edited October 26, 2017 by Guest

[hyycam 0]

At the moment, all my parts are stock parts. Though if these issues keep up, perhaps I will have to consider switching to a different hotend...

I tinkered some more with much higher retraction speeds and distances, to the point where cura was turning the boxes orange. But it doesn't seem to be doing anything. I also turned on the 'coasting' setting, where the end of the extrusion path is turned into a travel move and increased the travel speed, but still the strings!

Is it possible there is some issue in the hot end? I can see that the filament is retracting but that doesn't seem to be relieving any pressure. I even timed it so I stopped the print when the filament was retracted and a lot of material oozed out right away. Any thoughts?