Adding Perimeter modifier creates new internal perimeters
 
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David@3DOMEngineering
(@david3domengineering)
New Member
Adding Perimeter modifier creates new internal perimeters

I want to create holes in the perimeters to allow the internal volume to vent when compressed. 

When I added a set of custom modifiers from an STL. As expected it removed the perimeters leaving a hole. But it also added perimeters to the modifier shapes. This means it is still a sealed volume which is not what I want. 

I noted that it did the same with the generic shapes. 

Any suggestions hoe to print this with holes?

see image here. 

Napsal : 10/08/2020 1:42 am
Neophyl
(@neophyl)
Illustrious Member
RE: Adding Perimeter modifier creates new internal perimeters

Unfortunately no.  Thats the way modifiers work, they are in effect separating the model when it applies the different settings.

Even if they didn't work that way I don't think they would do what you want anyway.  While you can use a modifier to make a hole completely through something I don't think it will work to get a hole into the interior infill.  Even using some other software to make holes given the nature of a 3d model being about needing to be manifold to be valid then anything that shows the infill is NOT manifold and so would be a broken model. 

I have seen modifiers used to remove the top/bottom layers showing the infill but not with perimeters.  Happy to be proved wrong though as I am always up for learning something new. 
Do note that if you look at your holes through the perimeters if you set the top and bottom layers to zero then there will be small gaps top/bottom as they will be missing.

Why not just take a small drill bit and make a few holes ?

Napsal : 10/08/2020 6:10 am
David@3DOMEngineering
(@david3domengineering)
New Member
Topic starter answered:
RE: Adding Perimeter modifier creates new internal perimeters

Thanks for the feedback neophyl, I was hoping it would work like the top and bottom layers.  🙁

I could certainly hot knife out a section. and that is likely what I'll have to do if that is what i comes to. The difficulty is this is flexible filament and I was hoping to avoid needing to do that. Mainly for convenience, but also for aesthetics. 

Napsal : 10/08/2020 10:00 am
Neophyl
(@neophyl)
Illustrious Member
RE: Adding Perimeter modifier creates new internal perimeters

I see flexible filament, yeah it doesn't drill too well.  Instead of putting in a cylindrical modifier how about putting in a very thin cube/slot ?  That way you could set the top/bottom layers to zero and pressure would ventilate from the infill into the slot and then out.  A slot would have a larger surface area with removed top and bottom infill and might be aesthetically pleasing enough.  Vary the depth of the slot modifier and you can control how big the holes are.

Napsal : 10/08/2020 10:07 am
David@3DOMEngineering
(@david3domengineering)
New Member
Topic starter answered:
RE: Adding Perimeter modifier creates new internal perimeters
Thats an interesting alternative. I'll definitely give some vari5of that a go. Thanks. I'll share what happens. 
Napsal : 10/08/2020 12:07 pm
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