Suggestions for supports parameters to ease removal of top interface layer?
 
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Suggestions for supports parameters to ease removal of top interface layer?  

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ga
 ga
(@ga)
Trusted Member
Suggestions for supports parameters to ease removal of top interface layer?

I'm printing something with a flat top and nothing underneath it.  I've tweaked supports params to the following:

  • First layer expansion             2 mm
  • Pattern spacing                      5 mm
  • Top interface layers               1
  • Interface pattern spacing       1 mm
  • Support on build plate only   yes

However, I still find it virtually impossible to remove the top interface layer.  The 1mm separated threads don't come away with the rest of the support structure.  I need a way for the interface layer to attach better to the support structure below it?  Suggestions?

Best Answer by Neophyl:

Ive ben using the new snug supports in 2.4 recently and doing a fair bit of flat surface on top of support printing too.  Getting way better results than PS ever used to give with any previous settings.

First Layer expansion =0
Snug Supports
0.2mm contact z distance.
Pattern spacing anything between 1-3mm depending on model
Closing Radius =2 (currently left on default, haven't experimented with it as yet)
Top interface layers =4 <- this is the really important one I think along with the contact z distance.
Interface Pattern spacing = 0.2 (leave it close)
Bottom interface layers=0 <- seems to work better/easier to remove when the supports are on top of the part
XY Separation= 70-100% depending on model geometry.

Also and this is a MUST, turn Thick Bridges=OFF

With the above settings with PLA I am getting supports that just peel off by hand mostly, and the bottom surface that is bridged is much much better.  No where as good as the top but its not ever going to be if you want to be able to remove the supports at all.

Your settings are actually the reverse of what I use.  You are spacing things out and its having the opposite effect to whats desired.

By having more interface layers that are closer together and more of them to make it thicker that section is stronger if you will, it means when you pull on part of it that its stays in one piece mostly and just comes away in one section.  This in effect make support separation easier as with your settings I suspect it just unravels and snaps and leaves bits behind that you then have to manually remove bit by bit.

My support removal technique is  if the support goes down to the bed then you just pull it directly away from the surface its been supporting.  Generally that works, if getting your thumbnail on the edge of the interface layers and pushing away from the surface.  If its between 2 parts of the object where that's not possible, is to break away the thin tall support below the interface layer and clear it away with needle nose pliers.  This then leaves the interface layer and once the rest of the support is gone it then has room to pull away from the surface like before.
Think of the support interface layer and your object a bit like velcro, you can separate velcro if you pull it directly away but you cant slide it off sideways.  Same basic technique for supports, they come off easier if you can exert force away from the surface.  

This topic was modified 7 months ago by ga
Posted : 14/02/2022 7:57 pm
Neophyl
(@neophyl)
Famed Member
RE: Suggestions for supports parameters to ease removal of top interface layer?

Ive ben using the new snug supports in 2.4 recently and doing a fair bit of flat surface on top of support printing too.  Getting way better results than PS ever used to give with any previous settings.

First Layer expansion =0
Snug Supports
0.2mm contact z distance.
Pattern spacing anything between 1-3mm depending on model
Closing Radius =2 (currently left on default, haven't experimented with it as yet)
Top interface layers =4 <- this is the really important one I think along with the contact z distance.
Interface Pattern spacing = 0.2 (leave it close)
Bottom interface layers=0 <- seems to work better/easier to remove when the supports are on top of the part
XY Separation= 70-100% depending on model geometry.

Also and this is a MUST, turn Thick Bridges=OFF

With the above settings with PLA I am getting supports that just peel off by hand mostly, and the bottom surface that is bridged is much much better.  No where as good as the top but its not ever going to be if you want to be able to remove the supports at all.

Your settings are actually the reverse of what I use.  You are spacing things out and its having the opposite effect to whats desired.

By having more interface layers that are closer together and more of them to make it thicker that section is stronger if you will, it means when you pull on part of it that its stays in one piece mostly and just comes away in one section.  This in effect make support separation easier as with your settings I suspect it just unravels and snaps and leaves bits behind that you then have to manually remove bit by bit.

My support removal technique is  if the support goes down to the bed then you just pull it directly away from the surface its been supporting.  Generally that works, if getting your thumbnail on the edge of the interface layers and pushing away from the surface.  If its between 2 parts of the object where that's not possible, is to break away the thin tall support below the interface layer and clear it away with needle nose pliers.  This then leaves the interface layer and once the rest of the support is gone it then has room to pull away from the surface like before.
Think of the support interface layer and your object a bit like velcro, you can separate velcro if you pull it directly away but you cant slide it off sideways.  Same basic technique for supports, they come off easier if you can exert force away from the surface.  

Posted : 14/02/2022 8:29 pm
ga
 ga
(@ga)
Trusted Member
Topic starter answered:
RE:

Thanks.  Why the relatively narrow pattern spacing?  I used 5mm because it seems plenty adequate to get up to the interface layer (in my case, large regular geometry rectangles) and the first interface layer should be able to span 5mm easily.

I see the logic of close interface spacing and more layers.  I presume you need close so they can support each other?  I was thinking more separation and they would break easier, but was afraid to use more than 1 layer because I thought they wouldn't stand up.  Have you tried more separation and more than one layer?

What's the effect of turning thick bridging on?  Is that applied to the support structure as well as the work piece?  Seems like it would be nice if it could be restricted to only the work piece.

This post was modified 7 months ago by ga
Posted : 15/02/2022 1:49 am
ga
 ga
(@ga)
Trusted Member
Topic starter answered:
RE: Suggestions for supports parameters to ease removal of top interface layer?

Thanks again.  Worked great with

  • First Layer expansion           0 mm
  • Contact z distance                 0.2 mm
  • Pattern spacing                      5 mm
  • Top interface layers               3
  • Interface pattern spacing       1 mm
  • Support on build plate only   yes
  • XY separation                       100 %

How did you set top_interface_layers to 4?  I only see 0,1,2,3 in my version 2.4.0

Posted : 15/02/2022 3:27 am
Neophyl
(@neophyl)
Famed Member
RE: Suggestions for supports parameters to ease removal of top interface layer?

As I put in my comment against the regular pattern spacing I do vary that depending on the geometry that I'm supporting.  The problem with larger values is that it can cause more expansion of the supports.  Now this is mainly a left over for the non snug supports but previously when the supported feature ended up being say 1mm past the previous support structure then it would have to move out 5mm to lay down the next in the grid pattern.  This would result in the support moving out 4mm past the part.  With a spacing on 2mm then it would only move the support out an extra 1mm past the part.  Set it to 1mm and it didn't expand outwards far at all. Again some of the settings can be a bit counterintuitive. This used to be the best way to stop the massive outwards expansion PS does/did for support.
With snug support though this seems to not be such a problem which is why I'm using it as my default now.

The interface layer I don't want breaking up at all if I can help it so the 0.2mm spacing on it is fine.  Admittedly the extra layers are the thing that really helps it stay together but I've been getting such good flat bridged surfaces on it that I'm disinclined to change it.  The number of layers is just a value, type in however many you want, you aren't limited to the values in there.  Type 10 or 20 if you really wanted to.
4 layers give me a flexible yet solid layer that will usually peel off in one part.

Thick Bridging is the old behaviour that PS used for anything it classed as bridging prior to 2.4.  This meant all extrusion widths and heights was assumed to be the same as the nozzle diameter.  So you would get a 0.4mm high layer in those areas even if you were printing at 0.2 or 0.05.  It resulted in saggy bridge bottoms, same with overhang perimeters and bridge infill inside the model was also thicker.  There is some logic behind it historically but prints look better with the thin bridge option, probably due to printers and filament being a bit better now than they used to be.  Basically just turn thick bridges to Off and leave it off.  There's zero reason to have it on.  Its only a legacy holdover.  
Also remember that you were printing a 0.4mm thick layer on top of the support so it had to also adjust the support down too.  Its one of the contributing factors for PS having a reputation at being bad at bridges.  It was compared to some of the other slicers but 2.4 is much much better if you get the settings right.

Posted : 15/02/2022 7:16 am
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