Dealing with stringy prints with hollow objects

[alitech 0]

Hi guys

Hope you can help. I have a UM2 and I am new here. I bought a used one and trying a few things. I have not been able to find an answer for this through search and google.

My solid prints are fine and also the ones that require infill however, when I try to print anything hollow like a glass or vase, the prints are pretty stringy and dirty from from the inside but pretty good on the outside. The outer layer seems to be printing at lower speed and comes out fine, but the internet layer is a very quick run and usually tends to leave a lot of strings internally. I am not sure how to deal with this, any help would be really appreciated.

Furthermore, if anyone can tell me a way where I can print hollow and not have a top layer printed, that would be great. All hollow vase or glass type prints usually print a dirty top layer which I have to remove manually after the print.

If there is a way to deal with these 2 problems, that would be great. I am on cura 2.4

Thanks.

Ali

[vincentbaas 17]

For the top layer it might be wise to check both the layer view and the X-ray view in Cura. Both will show you if there's something wrong with your settings / model before committing to a print. Also, there should be a setting somewhere that removes the top surface, but right now I can't remember which one it was. Maybe someone else can jump in here?

The stringing in the vase might be a result from the combing setting, which deposits some material inside your object while minimizing retractions. Might be related to Cura thinking that the model should have a closed top. No problem for solid objects, but of course not for hollow stuff. So turn combing off should help here. But for vases there also is the Spiralize option, which prints your entire vase in one spiral trajectory, without moving through the middle at all.

Hope this helps!

Edit: I guess setting your top thickness to 0 should also do the trick here. And for spiralize: forgot to mention that this will only give you a vase of 1 layer (= your nozzle diameter) thick.

[fergazz 59]

Hi there,

as far I know strings usually happens on thin walls, specially with layes that don't have time to cold properlly. If you lay down speed (as it happened on the outer perimeter) it will avoid this issue... other solution should be lay down temperature a little bit, like -2°C. And a third solution is set minimum layer time to more than is setted, for exemple, if it is setted to 10 seconds put it to 15 seconds... but keep in mind that it will make your time print longer. As our friend said above you can print vases using spiralize on advanced page. If your nozzle is 0.4mm you can set the wall (yeah, just one wall) to a bit wider, like 0.6mm, and the printer will flow more plastic to do it.

To make an object without top layers just set top layers to 0, make sure to use infill 0% or you will see infill traces on the inside.

For more information take a look at this awesome guide to prevent a lot of issues: http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide