Help understanding PVA support settings

[JD-Art 1]

Hi my name is John. And I'm new here to the forum. 🙂

I have been working with 3D printing for some years on a hobby level, mainly on a Prusa.
And just recently upgraded to a dual head Ultimaker printer.

 

So I'm totally new to Pva support. and have a question I hop to get some help whit.

 

Using Cura 4.4.1
Im trying to make full support of the Pva "Good tight squise 😉" 

Support Z, Top and Bottom distance. all set to 0
Support x/y distance set to 0

 

"I think its a problem whit my stair height, but not 100% sure"
Support stair height set to 0 (default 0.1 gives same result)

 

Expectations settings all to 0 its a print where the Pla and Pva has no air between them. eg.

Green: Pla, Yellow: Pva

 

But most the time I get this. dual layered pva with pla squished on top of it

 

Sorry for the image quality

 

 

Looking Forward to hearing any suggestions.

 

 

 

[geert_2 557]

I do not have a dual nozzle printer, so no personal experience. But I do vaguely remember that supports might be printed at double layer-height, or beginning from a thicker minimum, or something like that, since it does not melt so nice as PLA. So, if the PVA would print at 0.2mm layers, and PLA at 0.1, you might get this effect. Could be an explanation. But I am not sure, it is just a vague memory, you need to check. Maybe you could search for this and find more info?

 

[JD-Art 1]

Hej Geert
Thanks for the reply. I'm not sure this is the problem, as far as I can see both extruders have 1.0 layer height set in Cura.  "don't know if Cura have some hidden setting overwriting this?"

 

When looking at the print, to me it looks like its the same layer height. the Pva just prints every other layer double.

 

Also when the (Support Stair Step Height) has the same value or lover then the layer height. this should not effect it. right?

 

[JD-Art 1]

Hi all

I still have a problem with the PVA layers, any thoughts! 🙂

 

Also if anyone have some ideas to reducing the start blob. I'm already using the coasting function. Whits make me think it more a layer start problem then layer ending problem?

[bagel-orb 61]

Die you try reducing the support infill layer height?

 

Could you please attach a model file for us to look at? Which layer are you seeing this problem?

[JD-Art 1]

test_top_v3.stl

Hi. here's the .stl thanks for helping.

 

The layer problem is on all layers with Pva so from 0-16 approximately.

"start blob is on all layers"

 

Yes all layer heights are set the same.

 

Pla layer height: 0.15

Pva layer height: 0.15

Support stair step height: 0.15 (set to 0 gives same result)

Support layer thickness: 0.15

Support interface thickness: 0.15

Support interface resolution: 0.15

 

 

[bagel-orb 61]

Sharing your project is a lot easier. Just save the project and send that file, so that all settings are automatically included.

 

For now I'll just reproduce your project from your description though..

[bagel-orb 61]

You were going in the right direction, but amde a wrong turn.

 

Reducing the stair stepping to zero prevents some unwanted behavior, but reducing the interface thickness is a bad idea. That makes the interface areas very small, such that they sometimes are too small to be printed. If you don't want a support interface you can simply disable it.

Other than that you might want to set the minimum support XY distance to zero as well. Or set the Priority to XY overrides Z.

 

See the project file attached.

UM3_test_top_v3.3mf