Can someone help me better understand interface loops?
 
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Amoda
(@amoda)
Eminent Member
Can someone help me better understand interface loops?

I have been playing around with support settings for tabletop miniatures. I have had great success but am always looking to improve. One thing I see referenced is using interface loops. However, I don't know that I understand the role they play. I think they are intended to reduce object scarring when supports are removed. That said, when I use interface loops, I get failed noodle wad prints after the first 100 layers. (printing at 0.05, so that's just around the feet of my model) I am guessing this is user error on my part due to some of the other settings I have fiddled with. Can someone give me a lesson or at least a sanity check? I'm not looking to problem solve supports in general, just looking to understand the role of interface loops and why my prints with them fail. 

Thanks!

My (probably strange) settings:  

General: Printing at 0.05 with a 0.25 nozzle. 

Raft: 2 Layers, 0.07 Z-distance, 1.5mm expansion

Supports: 

  • Style - Snug
  • Top Contact Z-distance - 0.25
  • Bottom '' - Same as top
  • Pattern - Rectilinear
  • '' Spacing - 1mm
  • '' Angle - 45d
  • Closing Radius - 2mm
  • Top Interface Layers - 2
  • Bottom '' - Same as top
  • Interface Pattern - Rectilinear
  • '' Pattern Spacing - 0.2mm
  • '' Loops - Yes
  • XY Separation - 130%***

That last setting is a bit unusual for me. I normally let that hover at 50%, but when I add interface loops I get an error unless I bump this up to 130%. This also makes me I think I may have a clash of the settings based on not understanding how the parts interrelate. 

Opublikowany : 20/01/2022 2:35 pm
bobstro
(@bobstro)
Illustrious Member
RE: Can someone help me better understand interface loops?

Interface loops are a legacy feature that I suspect has been obviated by new developments. The clearest explanation I found was in an old Thingiverse post from 2017 describing then-new Slic3rPE features:

The support interface layers were covered by "interface loops" by default in the old Slic3r. Now the "interface loops" are switchable and disabled by default. With the interface layers enabled but the "interface loops" disabled, the objects overhangs are well defined. Spacing between the object and its support in the XY plane could now be configured by a new parameter "support_material_xy_spacing". 

In my testing, I got better results with increasing the contact Z distance to 0.25mm and disabling loops. I use XY separation of 75%. Provided there is enough separation, the exact value shouldn't matter too much. Increasing XY distance will make removal easier but risks less support. 

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Opublikowany : 20/01/2022 4:43 pm
Amoda
(@amoda)
Eminent Member
Topic starter answered:
RE: Can someone help me better understand interface loops?

Thanks. It helps to understand that this feature is a legacy one and not one that I need to invest time in. Though I may still fiddle with it. If anyone else knows the reason for it, I would be interested. 

My 'go to' settings have been top contact z distance of 0.07 (slightly greater than my layer height) and XY separation of 150%. I may try your settings for kicks and see what happens. 

Opublikowany : 20/01/2022 5:01 pm
bobstro
(@bobstro)
Illustrious Member
RE: Can someone help me better understand interface loops?
Posted by: @amoda

Thanks. It helps to understand that this feature is a legacy one and not one that I need to invest time in. Though I may still fiddle with it. If anyone else knows the reason for it, I would be interested. 

A lot of Slic3r information (from which PrusaSlicer evolved) is hard to find. My understanding is that early supports were very slow and difficult to remove. Loops were used atop dense interface layers to prevent forming a permanent bond, particularly back when supports were just printed with very little fine tuning possible. Slic3r took a different approach from many/most other slicers with supports. They implemented features that helped a lot when ABS was the primary material and bridging didn't work very well, but don't add much for PLA or other newer filament types.

There are still a few legacy settings in PrusaSlicer that have proven to be time wasters IME. 

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Opublikowany : 20/01/2022 5:26 pm
Amoda
(@amoda)
Eminent Member
Topic starter answered:
RE: Can someone help me better understand interface loops?

Thanks for the additional insights. With your settings do you turn off interface layers entirely?

Opublikowany : 20/01/2022 6:27 pm
bobstro
(@bobstro)
Illustrious Member
RE: Can someone help me better understand interface loops?
Posted by: @amoda

Thanks for the additional insights. With your settings do you turn off interface layers entirely?

I generally use 2 or 3 interface layers, although this sometimes has to be adjusted for the model. If I'm printing a large flat horizontal overhang, I always use interface layers with loops disabled. For more delicate, complex prints like miniatures, I still try to use 1 or 2.

 

My notes and disclaimers on 3D printing

and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan

Opublikowany : 20/01/2022 8:03 pm
Amoda
(@amoda)
Eminent Member
Topic starter answered:
RE: Can someone help me better understand interface loops?

Much appreciated. I've been happy with my results in general, but I know I have a lot more to learn when it comes to the slicer rectilinear supports. Thanks for the response. 

Opublikowany : 20/01/2022 10:05 pm
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