Newbie question: Why part of my object does not have top, bottom or walls?

[jariiko 0]

Does anybody have an idea what went wrong here? For some reason part of the object I was trying to print failed to print correctly and I can’t figure out why. As you can see from the picture, the upper part of the object does not really have top, bottom or walls. It’s mainly just some fluffy plastic junk. I’m a complete beginner and this was the second time I tried 3d printing, so maybe there is some obvious thing that I just don’t see yet.

 

I designed the object in Tinkercad, sliced the stl with Cura 4.3. and used Ultimaker 3 in a local library. The material was PLA through 0,4 mm nozzle. I had the wall thickness as 1 mm as well as top/bottom thickness and the layer height was 0,15 mm. The object consists basically of two blocks. Lower block (with three separate small cylinders) is created straight from an svg in Tinkercad. Upper block, which failed to print, is multiple small boxes with rounded corners grouped together with the grouping tool. I did this to make the radius of the corners independent of the length of the side. I also grouped the upper and lower blocks together. I don’t know if this is of any relevance, but the two blocks had different colors in Tinkercad.

 

Here’s a link to the design in Tinkercad: https://www.tinkercad.com/things/iVaISPunbg9/edit?sharecode=4tjiM63O1_z6531hpP3psR9P5ryCa0o86oVnGYGl_J8=

 

 

Thank you for your help in advance!

[gr5 2,172]

There are 2 obvious possibliities:

1) Something wrong with model.

2) Something wrong with printer (underextruded).

 

Because this is a dual color print I suspect #1.  What does your part look like in PREVIEW mode?

 

[gr5 2,172]

Okay - so I just looked at the model in tinkercad and one problem is that the white part in the image above is supposed to be above the round part.  

 

I suspect tinkercad is exporting it where it touches z=0 which is bad - you want the second part to be up in the air.  You could move it up manually (menu item: preferences -> configure cura.  Then uncheck "ensure models are kept apart" and uncheck "automatically drop models to build plate".

 

And NEVER PRINT anything without checking PREVIEW mode first.  That would have shown you that it wasn't going to print right.

[jariiko 0]

Hi gr5,

 

Yes, the more rectangular part that failed is supposed to be above the rounder part, but I thought they should have been considered to be one part by Cura, since I grouped them in Tinkercad. I haven’t found any other merging tool in Tinkercad. The white showing below the fluffy stuff is the support.

 

I checked the preview on my own pc before and to me it looked just fine. I didn’t know if I could use the gcode file created on my own computer so I tried to remember to do all the changes in Cura at the library and did the slicing there. While at the library I had so little time that I didn’t realize I should have checked the preview. I have to keep that in mind.

 

However, if I open the file now in Cura on my own computer and see the preview it seems to me that those two parts are considered to be one part by Cura. So I don’t think the problem is in Cura exporting the upper part lower.

 

You mentioned also the possibility of under extrusion. I’m annoyed that I didn’t check the printer better at the library so I don’t know if there was a problem with the feeder, but wouldn’t it be strange if the problem would start so clearly with this part only.

[gr5 2,172]

It could be that one feeder is fine and the other one has a problem and hence underextrudes.

 

[gr5 2,172]

Maybe you could show a less vertical view of the failed part?  In the photo it looks like the white parts starts at the print bed.  Is it lifted up a bit?  Or all the way down?

[jariiko 0]

Sorry, I don't have a photo from a different angle at hand, but here are a couple of photos from the other side.

 

 

I would say the white part is the support structure and it was all the way down to the print bed. At least it was easy to tear apart.

 

[jariiko 0]

It seems to me that the fluffy plastic is gray so it came from the same extruder as the bigger part below. I think this all would suggest that there is something wrong with the model stl or that Cura wasn't able to handle it properly. I don't think I could have done anything differently in Tinkercad so maybe there's some kind of bug in either software.

[gr5 2,172]

The views are 2D but I need to see what's going on in 3D (or at least another angle):

1) tinker cad model

2) preview mode

3) final printed part

 

Without being able to see all 3 of those from an oblique angle it's really hard to see what you are talking about.  Sorry.

 

Also knowing which photos are from above and which from below the part (it's somewhat symmetrical so it's hard to tell which photos are which).

[jariiko 0]

No problem. My tutor didn't see any obvious problems in the model and suggested me to just try printing it again. So I tried that with slight modifications. I lowered the upper part half a millimeter so it would be that much inside the bigger part and changed the elements to have the same color in Tinkercad (normally Tinkercad sets elements as same color when they are grouped but for some reason not with this model). This time it printed without any problems. Maybe the problem was just about some weird handling of the model either in Tinkercad or Cura.

 

By the way the first picture is from above and the two next photos are from below. The part is going to be a printing block for printing on fabric.