Dissolving support weird slicing issue
 
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Henryhbk
(@henryhbk)
Estimable Member
Dissolving support weird slicing issue

printing a faceplate for the amazing 737diysim FMC (working 737-800 flight management computer for MS flight sim) see here

Anyway the issue is seen below, on the round keys (numeric) the slicer did full support (all the openings are overhangs to retain the keys/screens) but on the square keys (letters) you get the side towards us a wall of full support and the opposite as seen gets a little post of support. If it was one or two keys, I’d assume the BVOH fell or something but all 26 being identical makes it intentional. As it turns out the little pillars kept the overhang pristine, so while possible to guess that prusaslicer did this deliberately, since the keys are perfectly square no reason to do one side as full support. The weird thing is the corner supports are much, much harder to dissolve (after soaking 30 mins my toothpick broke scraping it off). I can’t distribute the model under the license (but the build guide above has links to Karl’s site) this is my first FDM build of this part as resin feels better, but was too low on gray to kick it off.

prusament recycled pla (don’t worry it gets a hit with the Boeing gray) in extruder 4

matterhackers BVOH in extruder 2

both using stock profiles, both spent the night in the filament dryer (it is a dreary rainy fall), 0.15 structural, supports everywhere (way to many surfaces to hit by hand!)

satin sheet (best sheet in my opinion) freshly cleaned

Photo below

Postato : 27/09/2024 12:07 pm
Neophyl
(@neophyl)
Illustrious Member
RE: Dissolving support weird slicing issue

Not weird at all.  Stock profiles usually have 'Don't Support Bridges' enabled.  As long as there's connection at each end it will try and bridge the distance in between.  If you examine your sliced print preview you would probably find those areas are keyed as dark blue.  If you had attached a PS project file we could check but my money is on the don't support bridges setting.

This is why carefully checking the preview options and stepping through layers before printing is an important habit to acquire.  Sometimes it tries to do bridges that are far longer than it can do so you need to check.

Also re: the comment about using auto as there's far too many spots to do by hand, have you tried the support painting tool option for auto painting?  Its surprisingly good and its easy to then use it as a basis and modify the areas with the human touch.

Postato : 27/09/2024 1:07 pm
Henryhbk
(@henryhbk)
Estimable Member
Topic starter answered:
RE: Dissolving support weird slicing issue

I think there are 75 seperate overhangs or something, most of which are like 1.5mm wide. It did a great job painting the screen bezel (and use it al, the time).

 

btw: my problem isn’t that it did little pillars in the corner, it’s that on one side it did a full support and the other is just pillars, in a fully symmetrical shape?

Posted by: @neophyl

Not weird at all.  Stock profiles usually have 'Don't Support Bridges' enabled.  As long as there's connection at each end it will try and bridge the distance in between.  If you examine your sliced print preview you would probably find those areas are keyed as dark blue.  If you had attached a PS project file we could check but my money is on the don't support bridges setting.

This is why carefully checking the preview options and stepping through layers before printing is an important habit to acquire.  Sometimes it tries to do bridges that are far longer than it can do so you need to check.

Also re: the comment about using auto as there's far too many spots to do by hand, have you tried the support painting tool option for auto painting?  Its surprisingly good and its easy to then use it as a basis and modify the areas with the human touch.

 

Postato : 28/09/2024 2:35 am
Henryhbk
(@henryhbk)
Estimable Member
Topic starter answered:
RE: Dissolving support weird slicing issue

On the top filament preview the beige is the BVOH obviously and the dark gray is the PLA. The bottom shows the "bridge" is purple which if I recall is top layer?

Note the first alpha key on the left (right below the circular number keypads) has a different support pattern despite being absolutely identical to all the others

Postato : 28/09/2024 2:46 am
Neophyl
(@neophyl)
Illustrious Member
RE: Dissolving support weird slicing issue

Again without a project file to examine layer by layer it’s difficult to figure things out. 

While the button hole geometry ‘should’ be identical (but have you examined it at the vert level to make absolutely sure) it’s placement relative to other features around it is not. For example it’s the only one with a circular button above it AND that’s next to the thinner outer wall. That will cause the slicer to use a different amount of perimeters, or possible different thickness perimeters if using Arachne. Different widths then different support requirement. That’s one possibility. All it takes is a so,etching being a tiny tiny fraction different and the slicer can do something different. 

Postato : 28/09/2024 7:16 am
Henryhbk
(@henryhbk)
Estimable Member
Topic starter answered:
RE: Dissolving support weird slicing issue


i checked it is turned off (but also the slicer doesn't think most things I would all bridges are bridges (almost nothing with a blue pattern including the bottom holes for threaded inserts which have a top)

Posted by: @neophyl

Not weird at all.  Stock profiles usually have 'Don't Support Bridges' enabled.  As long as there's connection at each end it will try and bridge the distance in between.  If you examine your sliced print preview you would probably find those areas are keyed as dark blue.  If you had attached a PS project file we could check but my money is on the don't support bridges setting.

This is why carefully checking the preview options and stepping through layers before printing is an important habit to acquire.  Sometimes it tries to do bridges that are far longer than it can do so you need to check.

Also re: the comment about using auto as there's far too many spots to do by hand, have you tried the support painting tool option for auto painting?  Its surprisingly good and its easy to then use it as a basis and modify the areas with the human touch.

 

Postato : 29/09/2024 12:17 pm
Henryhbk
(@henryhbk)
Estimable Member
Topic starter answered:
RE: Dissolving support weird slicing issue

 

Posted by: @henryhbk

I think there are 75 seperate overhangs or something, most of which are like 1.5mm wide. It did a great job painting the screen bezel (and use it al, the time).

 

btw: my problem isn’t that it did little pillars in the corner, it’s that on one side it did a full support and the other is just pillars, in a fully symmetrical shape?

Posted by: @neophyl

Also re: the comment about using auto as there's far too many spots to do by hand, have you tried the support painting tool option for auto painting?  Its surprisingly good and its easy to then use it as a basis and modify the areas with the human touch.

 

The automatic painting really did not do a good job at deciding what to do? Hand painting it is with the smart fill (with overhangs only turned on) (Getting the BVOH out of the screw holes was less fun with lots of hot water and toothpicks)

Postato : 29/09/2024 12:21 pm
Henryhbk
(@henryhbk)
Estimable Member
Topic starter answered:
RE: Dissolving support weird slicing issue

Did the hand painted (smart fill) on the overhangs that are most sensitive for smooth keyboard operation and it still does the weird single support thing except the single one which has the full support box inside, which on the 3D editor view certainly looks the same as the others, but on the preview (and actual print obviously) isn't the same. (OK, all together now for those kids who grew up on Sesame Street "which one of these is not like the others, which one is different do you know?")

Postato : 29/09/2024 12:35 pm
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