Support blockers don't block supports
 
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Gauthier
(@gauthier)
Eminent Member
Support blockers don't block supports

I'm trying to add cubes as support blockers for my model. Here are the models (blocker in green, I've set its type as Support blocker):

The resulting code still puts some support material within the cube:

How can I get rid of ALL support material within the support blocker?

Posted : 07/12/2021 9:27 pm
sylviatrilling
(@sylviatrilling)
Reputable Member
RE: Support blockers don't block supports

Please ZIP your .3mf file and post it here and let us know are you using PrusaSlicer 2.3.3 or 2.4.0?

Mk3S+,SL1S...
Posted : 07/12/2021 9:45 pm
micha
(@micha)
Eminent Member
RE: Support blockers don't block supports

Yikes! I just noticed the same behaviour in 2.4.0-beta3

Worked correctly till 2.4.0-beta1

Can anyone confirm that?

Posted : 07/12/2021 10:05 pm
sylviatrilling
(@sylviatrilling)
Reputable Member
RE: Support blockers don't block supports

Please attach a ZIPPED .3mf file. If you attached a file to your last post, it didn't work.

Mk3S+,SL1S...
Posted : 07/12/2021 10:10 pm
micha
(@micha)
Eminent Member
RE: Support blockers don't block supports

I'm not the original poster :), just tried to reproduce it.

Posted : 07/12/2021 10:25 pm
sylviatrilling
(@sylviatrilling)
Reputable Member
RE: Support blockers don't block supports

Oops, thanks for pointing that out. 

Mk3S+,SL1S...
Posted : 07/12/2021 10:39 pm
Gauthier
(@gauthier)
Eminent Member
Topic starter answered:
RE: Support blockers don't block supports

Prusa 2.3.0

Here is the zipped 3mf!

!

Posted : 09/12/2021 7:34 am
micha
(@micha)
Eminent Member
RE: Support blockers don't block supports

Hi Gauthier, I tested in 2.3.3. and, for me, it does exactly what it's supposed to. From your pictures, I'd say it works the same in 2.3.0. What results would you have expected?

Posted : 09/12/2021 8:56 am
Neophyl
(@neophyl)
Famed Member
RE: Support blockers don't block supports

Yeah thats about what I'd expect out of PS 2.3.x versions. 

All a blocker or an enforcer does is define areas on the model that should or should not be included for the support algorithm to process.  They are not keep out areas.  If something above a blocker needs supporting it will quite happily place support down through a blocker to the surface below.  Even if that surface below is covered in a blocker.  Btw the paint options are much better than the modifiers in general at defining areas.

That extraneous support interface is an artefact of the support for the lower surface.  The algorithm isn't clever enough to realise that its on top of that slope.  This has been reported many many times.

Luckily for you there have been many support related changes in the 2.4 builds (currently in beta status).  One of the new options is snug supports.  With that option enabled the support interface on top of the slope goes away on your project.  (sliced with beta3 and snug support turned on)

Posted : 09/12/2021 10:19 am
Gauthier
(@gauthier)
Eminent Member
Topic starter answered:
RE:

Good to know about snug support!

Unfortunately still a bit of artifacts, but it's better.

I'm not sure if I could try to play with other parameters to get rid of this? Why do I have this and you don't?

EDIT: it seems that moving the blocker around and having a little luck may fix this. Only that I need to do that 29 times. Then 29 more.

Posted : 09/12/2021 4:04 pm
Neophyl
(@neophyl)
Famed Member
RE: Support blockers don't block supports

That model shouldn’t really need the blockers though with snug supports, your example only had a single blocker and notice none of the other areas needed them. Personally I would use paint on enforcers, adjusting the angle settings to apply them and then select support for enforcers only and manually trim down the enforcer area if needed. Basically blockers are pretty much pointless now. Haven’t needed to use them for ages even without snug supports. And with snug things get even easier. 

The only setting I adjusted on your example besides turning supports from grid to snug was the bottom expansion. It’s default of 3mm, I changed it to either 1mm or 0mm, can’t remember which. I’ve been using the 2.4 alphas since they were released and it’s already become habit to turn that down and change to snug. 

Posted : 09/12/2021 4:36 pm
Gauthier
(@gauthier)
Eminent Member
Topic starter answered:
RE:

Oh I do need the blockers, I don't want any green above orange!

Painting is a pain, there are about 30 such wells (the 3mf is a partial print). I wanted to make and place the blockers in CAD, and import them at the right size and place directly (not that this is going well, but it was the plan)... the point being not having to repaint at the slight little change of the model.

Posted : 11/12/2021 11:45 am
sylviatrilling
(@sylviatrilling)
Reputable Member
RE:

Did you try support on build plate only with snug supports? No blockers or enforcers needed. Here is what I get.

Mk3S+,SL1S...
Posted : 11/12/2021 3:32 pm
Gauthier
(@gauthier)
Eminent Member
Topic starter answered:
RE: Support blockers don't block supports

This sounds so obvious when I read it 🙂

Thank you, it seems fine!

Posted : 12/12/2021 5:49 pm
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