Inadequate support of ceilings printing.
 
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Inadequate support of ceilings printing.  

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Sherri
(@sherri)
Eminent Member
Inadequate support of ceilings printing.

I've been 3d printing a few years and only just noticed this problem. 

I have a Mk2 and while using PrusaSlicer on a model I created, while scanning the layers, I noticed there was nothing supporting a solid layer.  Ordinarily, I print with 20-25% infill and 4 bottom layers, but on this particular model I was trying to reduce material and increase speed. 

My guess is that everyone is already aware of this issue and find that it generally resolves itself as successive bottom layers are printed. 

 I'm printing a cylindrical cup with 5% infill and thick walls.  When the printer begins to lay down the first bottom layer of the *interior* floor, the only support under it is the infill pattern.  That leaves edges wholly unsupported in areas and nothing to bridge between.  It seems that the slicer software should be able to identify these areas and create the first bottom by bridging between infill supports before reversing direction.

Is there some setting I'm missing?

 

Best Answer by bobstro:

Posted by: @sherri

You understand correctly.  Just for giggles I tried zero infill with supports just to see if it would support the ceiling.  That didn't work either.  I'll upload the file in just a bit.

Supports are separate from infill. Think of supports as "external" (outside the shell) and infill as "internal" (inside the shell). Supports can be taken off after printing (usually), infill is entombed internally.

If you just want a higher support density under the bottom of the bowl, you can use a modifier. Hopefully this pic shows the idea clearly:

I used the Support Cubic infill for the basic print to speed up print times but added a cylinder modifier under the bowl with infill set to 40% Grid pattern.

I've got notes on optimizing print times for larger prints here that might be useful.

Save your current  3MF project file, zip it up, and attach it to a reply here so we can see your part & settings and give better recommendations.

 

Posted : 04/10/2021 6:44 pm
bobstro
(@bobstro)
Illustrious Member
Sounds like interface layers are turned off

If I'm understanding you correctly, sparse infill is being printed, but it is insufficient immediately under the interior bowl. You could try support cubic infill and increase infill density. A lot depends on the specifics of the print. Save your current  3MF project file, zip it up, and attach it to a reply here so we can see your part & settings and give better recommendations.

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

Posted : 04/10/2021 7:21 pm
Sherri
(@sherri)
Eminent Member
Topic starter answered:
Thanks

You understand correctly.  Just for giggles I tried zero infill with supports just to see if it would support the ceiling.  That didn't work either.  I'll upload the file in just a bit.

Posted : 05/10/2021 2:51 pm
bobstro
(@bobstro)
Illustrious Member
You can add a modifier with denser supports under the bowl
Posted by: @sherri

You understand correctly.  Just for giggles I tried zero infill with supports just to see if it would support the ceiling.  That didn't work either.  I'll upload the file in just a bit.

Supports are separate from infill. Think of supports as "external" (outside the shell) and infill as "internal" (inside the shell). Supports can be taken off after printing (usually), infill is entombed internally.

If you just want a higher support density under the bottom of the bowl, you can use a modifier. Hopefully this pic shows the idea clearly:

I used the Support Cubic infill for the basic print to speed up print times but added a cylinder modifier under the bowl with infill set to 40% Grid pattern.

I've got notes on optimizing print times for larger prints here that might be useful.

Save your current  3MF project file, zip it up, and attach it to a reply here so we can see your part & settings and give better recommendations.

 

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

Posted : 05/10/2021 3:30 pm
Sherri
(@sherri)
Eminent Member
Topic starter answered:
That's exactly what I was looking for!

Thanks Bobstro!  I wasn't aware of that feature!

 

Posted : 06/10/2021 12:15 am
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