support layer thickness only 0.15 mm when rest is 0.3 mm
 
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support layer thickness only 0.15 mm when rest is 0.3 mm  

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mchahn
(@mchahn)
Eminent Member
support layer thickness only 0.15 mm when rest is 0.3 mm

I had a model with supports I manually designed.  This model had 34 layers up to a certain point.  Then I removed my supports and I changed it to use automatic supports from the base.  To my surprise it now has 69 layers to that point.  When looking closely at the layers I see that the support is built with half the layer height of the model, 0.15 mm instead of 0.3 mm.  As a result it will print a support layer with no model then print a layer with both supports and the model.  It is in the middle of printing now but I suspect the parts of my model from the base up will be missing every other layer and not be very strong.  I couldn't find any layer height setting for supports.

Has anyone else seen this happen?  Any ideas on how to fix this?  I don't know how to show this on a screen cap.

Best Answer by Swiss_Cheese:

@mchahn

 

This is normal behavior for slicer supports, slicer adjusts the height based on the settings you set, or are using. For example your using 0.2mm for the first layer, the first layer "extrusion width" is 0.42, then all other layers are printed at Draft 0.3, their "extrusion width" is 0.5, However the default "extrusion width" for supports at 0.3Draft is 0.38, so slicer has to set the layer height for those extrusions to 0.15 so they don't fail.

As well, Slicer is averaging the supports layer height, so that it can compensate for the difference between the 0.2 first layer and the 0.3 contact Z distance you have set in the support settings. (0.3 is to much "contact Z distance" for PLA it should be 0.2 or even 0.15).

The supports shouldn't have any bearing on the layers of the actual model, slicer will print them as they are set and the supports will reach the height they are set for. Your models layers will be as strong as ever.

 

Note: I would like to point out to you that you have "Don't support bridges" Ticked, and you have a very large unsupported bridging area in the middle, you may want to consider un-ticking it.

 

Hopefully this was helpful, I tried not to be to confusing, just ask if you need more help.

 

Regards

 

Swiss_Cheese

Posted : 24/11/2021 12:08 am
mchahn
(@mchahn)
Eminent Member
Topic starter answered:
RE: support layer thickness only 0.15 mm when rest is 0.3 mm

Correction.  It prints a model layer then a support layer then a model layer, etc.  It is as if the supports are shifted in the z-axis by 0.15 mm compared to the model.

Posted : 24/11/2021 12:16 am
Swiss_Cheese
(@swiss_cheese)
Noble Member

@mchahn

 

Can you post a Zipped up .3mf project file from slicer for us to review?

 

Note: if the file is not zipped the server will not allow you to post it.

 

Regards

 

Swiss_Cheese

The Filament Whisperer...
Posted : 24/11/2021 2:00 am
mchahn
(@mchahn)
Eminent Member
Topic starter answered:
RE: support layer thickness only 0.15 mm when rest is 0.3 mm

Here it is.

Posted : 24/11/2021 2:14 am
Swiss_Cheese
(@swiss_cheese)
Noble Member

@mchahn

 

This is normal behavior for slicer supports, slicer adjusts the height based on the settings you set, or are using. For example your using 0.2mm for the first layer, the first layer "extrusion width" is 0.42, then all other layers are printed at Draft 0.3, their "extrusion width" is 0.5, However the default "extrusion width" for supports at 0.3Draft is 0.38, so slicer has to set the layer height for those extrusions to 0.15 so they don't fail.

As well, Slicer is averaging the supports layer height, so that it can compensate for the difference between the 0.2 first layer and the 0.3 contact Z distance you have set in the support settings. (0.3 is to much "contact Z distance" for PLA it should be 0.2 or even 0.15).

The supports shouldn't have any bearing on the layers of the actual model, slicer will print them as they are set and the supports will reach the height they are set for. Your models layers will be as strong as ever.

 

Note: I would like to point out to you that you have "Don't support bridges" Ticked, and you have a very large unsupported bridging area in the middle, you may want to consider un-ticking it.

 

Hopefully this was helpful, I tried not to be to confusing, just ask if you need more help.

 

Regards

 

Swiss_Cheese

The Filament Whisperer...
Posted : 24/11/2021 3:22 am
mchahn liked
mchahn
(@mchahn)
Eminent Member
Topic starter answered:
RE: support layer thickness only 0.15 mm when rest is 0.3 mm

Thanks mucho.

> the 0.2 first layer

I actually tried 0.2 and 0.3.  It didn't make any difference.

> the default "extrusion width" for supports

Where is this specified?  I searched for anything related to supports.

> 0.3 is too much contact Z distance

Thanks for the tip.  I'm used to a slicer that can only specify support gap from the top in a number of layers.  So I just matched the layer height out of habit.

> Your models layers will be as strong as ever.

That's good to know.  I should just relax and trust prusaslicer.

> you have "Don't support bridges" Ticked

I was trying the giant bridge pretty much as an experiment.  I thought if I had the support under the bridge I might as well just use default supports under the whole thing and not rely on bridging.  I didn't think there was a difference.  Anyway, the giant bridge did fail miserably. Another failed experiment.  I ended up removing the feet and just printing it flat. with no supports or bridging.

> I tried not to be to confusing

You succeeded (in not being confusing).

Posted : 24/11/2021 4:43 am
Swiss_Cheese
(@swiss_cheese)
Noble Member

@mchahn

 

> the default "extrusion width" for supports

Where is this specified?

They are in Print Settings/Advanced/[Extrusion width] Support material: 

Note: (If no support is selected the box will be greyed out)

 

I should just relax and trust prusaslicer.

well, lets not get to carried away, slicer bears watching.

 

Bridging

Without failed experiments there would be no learning.

I mentioned it because so many before you did it because it looked so nice in the sliced view, they assumed that would be the reality.

 

Good luck with the print.

 

Swiss_Cheese

 

The Filament Whisperer...
Posted : 24/11/2021 6:50 am
fuchsr
(@fuchsr)
Noble Member
RE: support layer thickness only 0.15 mm when rest is 0.3 mm

One quick thought related to bridging. You can also change the angle at which the bridging filament is laid down. I don't think it would make much if any difference in your specific model but sometimes this is useful as PS for some reason often bridges along the longest dimension of a bridge. 

Posted : 24/11/2021 11:36 am
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