Rearranging support

[shcenator 0]

Hi all

 

This is my first post. At the moment im printing PETG with HIPS (both renkforce) as support on a UM3E. Support is printed in triangles. Generally it works like a charm. However, there are an issue on the bottom of some of the horisontal rods going through the design. These hang midair and need support big time. Most of them print well but at a few places (always in the same region) it seems like they lack support so quality suffer. I know this as it was previously more pronounced but after increasing support density problems diminished significantly. The model is rather complex with support density at 50%. Should I just keep increasing support density or is there a way to circumvent this by fx rearranging the support more efficiently? It would be really nice not having to end up printing a solid block in support. Also can Cura somehow tell me how much support it would need?

[shcenator 0]

Hi again

 

I did some prints on a new kind of piece and now it goes completely wrong. I have attached some pictures.  It seems like it always fails on the same side, even though the other side of the midline is identical. On the inside it seems like the model is bulging inwards at the point where it failed on the outside. It is as if the support interface was uneven or something. But why should that only affect one side at the same spot continuously?

 

I then tried to change some parameters of the interface, incl thickness, resolution and lines instead of concentric. Also I increased the support Z offset from 0 to 0.1 mm. Now it seems like there is even greater holes, although the surface looks more smooth.

 

Im new to all this so I apologize if im terrible at explaining myself. I really hope you can help.

[nallath 1,124]

You can tell cura to not support certain parts by using "anti-overhang meshes". You can also have a look at variable density for the support.

[shcenator 0]

Hi Nallath

 

Thank you so much for your response. Is anti-overhang meshes a thing in cura that comes standard? I cant see it anywhere. Also, as im new to all this I dont know if it is normal to have repeated issues on one side of a model that is absent on the other identical side of the model? Is it a software og hardware issue? Do you have any input on that.

[ahoeben 2,016]

It is a feature that has been available through "Per Model Settings" for a long time (I think since Cura 2.4 or so), but it will be made much more prominent in Cura 3.2 (expect a beta in around 1.5 week). See https://github.com/Ultimaker/Cura/pull/2758 specifically the part at the beginning of the (slow-to-the-tooth) gif animation.

 

As for your other question, yes it is fairly normal for issues in prints to be non-symmetric, since the printhead is not symmetric; though there's fans on both sides of the head, the left extruder is closer to the left fan. So when you print with the left extruder, the cooling is a bit different from the left then from the right. What you could do is rotate the part 90 degrees to see if that helps.

[ctbeke 133]

The updates @ahoeben describes are indeed in Cura 3.2. We're also thinking about how to further improve support structures without having to completely re-implement it.

[shcenator 0]

Thank you so much for all the input. Im looking into it and actually it might be due to fan problems. I recently started letting the exhaust from the ventilation in the cabinet, where the printer stands, blow into the open air outside. For some odd reason this might have changed air currents in the cabinet. After turning off cabinet ventilation prints looks nicer. So I guess it will in the end be a choice between nice prints or toxic fumes. Luckily we have free healthcare :-)

 

With regard to improving support structures, would it maybe be possible to make some kind of rafts as support roof on which the model rests? It seems people elsewhere on the net praise this in their slicers.

[ctbeke 133]

Cura already has this, it's called support interface in the settings.