Collapsing bottom side of a box  

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jmirage
(@jmirage)
New Member

After calibrating my Prusa Mini+ and being able to print some small objects I tried to print this box on a 250% scale: https://www.thingiverse.com/thing:2056532

I thought the obvious thing to do is to print it with the bottom of the box touching the bed. Using the standard settings I ended up with this mess:

Closer detail:

From what I can gather it seems like the "floor" of this box is quite thick and PrusaSlice is printing that side hollow and trying to print in mid-air. I can see something called bridge infill in the preview. Sorry, this is my second print and I'm still completely new to all this. Any ideas on what should I read about or a solution to it? Thanks in advance!

Posted : 08/01/2021 11:45 pm
jaswalt
(@jaswalt)
New Member

What infill % are you using?  It looks like the hollow structure underneath the upper floor of that layer is falling into the voids caused by too little infill.  I have had the problem myself.  Adjust to somewhere around 40% and try again.  If that doesn't work, try increasing 10% with each attempt.  I hope this works for you.  It did for me.  Oh, you can also try different infill patterns.  Some of them seem to work better at lower %s.

This post was modified 3 months ago by jaswalt
Posted : 09/01/2021 7:27 pm
ChillyPenguin
(@chillypenguin)
Trusted Member

Have faith, let it finish. It will be fine.

It's just that there is not support material under that end, as the layers build up they will support each other, and it will disappear.

You may want to increase the number of top layers. And as jaswalt said change the infill pattern. IMHO you should not need to go above 20%

 

Posted : 10/01/2021 7:57 pm
cwbullet
(@cwbullet)
Illustrious Member

That looks like some under extrusion.  I could be wrong.  

--------------------
Chuck H
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Posted : 10/01/2021 11:57 pm
jmirage
(@jmirage)
New Member
Posted by: @chillypenguin

Have faith, let it finish. It will be fine.

...

 

I didn't mention that in the first message, but the reason why I couldn't try letting it finish it's because some small strands of plastic were sticking up and out and when the nozzle went over that part again on the next layer I could hear some clicking of the nozzle against that sticking part.

thanks @jaswalt! I'll check if that solves it
thanks @cwbullet that's something I'll also check. I found this article about it. Is it a good way to start? https://help.prusa3d.com/en/article/under-extrusion_2007

Posted : 11/01/2021 8:55 am
Swiss_Cheese
(@swiss_cheese)
Honorable Member

I don't believe this is under extrusion, I think its bridging, if you look at the model you may notice it has one side thicker then the other, slicer will normally try to bridge these ares but not try to make it to the other side as it's planing to continue the wall upward in that area, you should simply let the print finish printing and watch it in that area to make sure, I think it will be fine.

This post was modified 3 months ago 2 times by Swiss_Cheese
Posted : 11/01/2021 4:04 pm
jaswalt
(@jaswalt)
New Member
Posted by: @chillypenguin

Have faith, let it finish. It will be fine.

It's just that there is not support material under that end, as the layers build up they will support each other, and it will disappear.

You may want to increase the number of top layers. And as jaswalt said change the infill pattern. IMHO you should not need to go above 20%

 

I guess I should have included that caveat, also.  With the correct infill pattern you very well could get down to 20%.  You'll find that different patterns have their strengths and weaknesses.  I will admit that I do tend to go a little heavy when it comes to infill.  Happy printing!

Posted : 11/01/2021 4:56 pm
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