What is the thin thing sticking to the print?
 

What is the thin thing sticking to the print?  

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prusanewuser
(@prusanewuser)
Reputable Member

Hi, usually I use PETG on coated sheet. In PrusaSlicer, I had Brims enabled and no skirt . When I tried PLA on smooth sheet with different slicers such as SuperSlicer (currently in use), PrusaSlicer and Cura, there is a think smooth kind-of shinny thing sticking to the bottom of the printed object. It seems impossible to remove that from the bottom surface. What is it? Can I get rid of it as trying to remove the extra bits on the edge could damage the print. When I double checked the settings, I noticed that Skirt was enabled with the following settings:

Loops (minimum): 1

Distance from object: 2mm

Skirt height: 3 layers

Draft shield: unchecked

Minimal filament extrusion length: 4 mm

Posted : 22/11/2020 2:28 pm
karl-herbert
(@karl-herbert)
Famed Member
Posted by: @prusanewuser

Hi, usually I use PETG on coated sheet. In PrusaSlicer, I had Brims enabled and no skirt . When I tried PLA on smooth sheet with different slicers such as SuperSlicer (currently in use), PrusaSlicer and Cura, there is a think smooth kind-of shinny thing sticking to the bottom of the printed object. It seems impossible to remove that from the bottom surface. What is it? Can I get rid of it as trying to remove the extra bits on the edge could damage the print. When I double checked the settings, I noticed that Skirt was enabled with the following settings:

Loops (minimum): 1

Distance from object: 2mm

Skirt height: 3 layers

Draft shield: unchecked

Minimal filament extrusion length: 4 mm

Pictures are always a helpful tool for error analysis. Could you make some available?

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 22/11/2020 3:39 pm
prusanewuser
(@prusanewuser)
Reputable Member

This thin thing. What is it?

Under Preview, you can see it has green zig-zag patterns around the edge. I have Skirt off (loops = 0), raft and brim turned off. 

Posted : 23/11/2020 5:09 am
prusanewuser
(@prusanewuser)
Reputable Member

Another trial

 
Photo taken from the bottom in Preview
This post was modified 2 weeks ago 3 times by prusanewuser
Posted : 23/11/2020 5:47 am
Neophyl
(@neophyl)
Noble Member

The thin zig zig pattern is the base of the support. You have support enabled and where it goes to the bed it always has that base pattern. There is no option to turn it off as it’s part of the support. 

Posted : 23/11/2020 6:12 am
prusanewuser
(@prusanewuser)
Reputable Member
Posted by: @neophyl

The thin zig zig pattern is the base of the support. You have support enabled and where it goes to the bed it always has that base pattern. There is no option to turn it off as it’s part of the support. 

Thanks. What is the best way to trim it off from the edges of the prints without damaging the prints? Tried knife but parts of the prints got shaved off.

From the Preview, you see that there are yellow perimeters and purple infill. Is there a way to make it solid looking?

Here is a photo of the bottom. As you can see, there are some holes and gaps among perimeters themselves, infill themselves as well as the boundary of the two. I want to make the bottom looks like solid like being ironed as well. Is it possible?

What are those ugly looking irregular lines that ruined the looks of the bottom surface?

This post was modified 2 weeks ago 2 times by prusanewuser
Posted : 23/11/2020 6:20 am
Neophyl
(@neophyl)
Noble Member

That looks like where filament hasn't stuck to the bed in that area and is dragged across where it shouldn't be.  It is absolutely vital that the bed is clean.  No fingerprint oils or anything else otherwise adhesion suffers in those areas.

Take your plate to the sink and wash it using plain dish soap (dawn/fairy or similar), scrub using clean paper towels, rinse with LOTS of hot water and dry with more clean paper towels.  That's it.  Do NOT touch the surface with your fingers after that, hold it by the edges only.  No IPA needed.

Your preview shows yellow perimeters and purple bottom infill.  How its printing is perfectly normal.  Assuming your live z value is set correctly to give a proper squish and that your extruder is pushing out the right amount of plastic (not clogged and the filament tuned properly) the plastic will all be fused into a single sheet on that bottom layer anyway.  If you don't like the visual pattern then select a different bottom infill.

As for the support base you could try setting your support xy separation to a larger %.   They shouldnt be attached at all, they should come off with the support itself.  Now depending on your support settings the support may be difficult to remove, especially if you are using defaults.  You would have to save your project (file >Save as) to save it as a .3mf file, zip it up into an archive and attach it here to be able to tell much more and to look at what settings you are using and how those effect the slice of the model you are using.

Posted : 23/11/2020 7:21 am
prusanewuser
(@prusanewuser)
Reputable Member

Thanks. What is the cause of those curling filaments shown in photo 2425? Bad bed adhesion? 

Posted : 23/11/2020 3:56 pm
Neophyl
(@neophyl)
Noble Member

Yes, or that and a combination of your live z might actually be too low so it’s drags back. The first layer looks pretty translucent but that might just be the filament you are using. Can’t tell without a single layer 75x75 square print to look at. 

Posted : 23/11/2020 5:34 pm
prusanewuser
(@prusanewuser)
Reputable Member

@neophyl

What is the unit of 75x75?

Posted : 25/11/2020 6:26 pm
Neophyl
(@neophyl)
Noble Member

There’s a three that details the best way to dial in the perfect first layer https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/

it’s involves printing a 75x75mm 1 layer thick square. As it’s printing you can adjust the z offset value until the lines merge properly. When it’s finished you can feel the top, if it’s rough then you are probably a bit too low.  Peel if off and flex it and if the strands separate or have any gaps then you need to go lower. Basically it should be a single sheet of plastic. 
The thread has some pre-done gcode you can print but I find it better to use your slice settings and printers start gcode. If you open a new session in Prusa slicer you can right click on the bed and add part>box. Then using the object manipulation panel (the panel at the right) click the padlock to unlock the scaling and you can then resize it by typing in x=75, y=75 and z=0.2. You then slice it and print as usual. It’s very quick and once you get the hang of it you can level your printer in minutes. 
Doing it yourself also means you can choose whatever filament you want as sometimes different filament types actually require a slightly different z offset. Petg for example often needs to be a bit further away from the sheet. 

Also make sure that you have enabled 7x7 mesh levelling in your printers lcd menu options instead of the default 3x3. It’s much more accurate as it probes 49 points rather than 9.

Posted : 25/11/2020 6:44 pm
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