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dm33

Bottom layer infill not quite reaching the wall

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I'm assuming its a Cura issue. The bottom layer inside the wall (infill?) comes very close to the wall, but doesn't quite meet. So in an otherwise smooth bottom, there's a gap, ie seam between the bottom and the wall. I'm also noticing some under extrusion on the bottom particularly when using concentric fill. 
 
Is there some setting to fix this? I'm using the default "draft 0.2mm" setting. This is on an Ender 3 with speed set to 40mm/sec.

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A picture would help.  But if the bottom layer (and only the bottom layer) is underextruded as you describe then maybe your bed needs to move closer to the nozzle.  You want to have a good squish on the bottom layer or the part will come off or at least corners will lift off.

 

Also the bottom layer tends to print much faster volume (0.3mm typically versus 0.1mm for the rest of the layers typically) so you may just be printing too cold or too hot.  But more likely it's a leveling issue.

 

The gap can also be partly caused by backlash/play.  Especially if it's not symmetrical. Here's more about backlash and gaps between wall and infill:

 

 

 

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On 8/23/2018 at 9:37 AM, smartavionics said:

It would help hugely if you could a) attach an image showing the gap between the bottom layer and the wall and b) attach the curaproject.3mf for the print (or even the gcode file). Thanks.

Attached is a picture. I don’t think it’s a printer issue. Belts are tight, prints are very consistent. Bed is very level and the wall extrudes to the edges well. It’s the bottom within the walls that doesn’t quite reach as in the attached picture. 

 

023AD325-4716-4817-8B80-A69C277EFFA8.jpeg

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So this looks like basic underextrusion - when underextrusion is on the bottom layer it's usually a leveling issue.  Notice the gaps between linfill lines as well.  

 

There is not enough filament coming out to fill in the gaps on the bottom layer.  If this is happening on every layer then you are printing too cold or too fast for your extruder/nozzle combination.  But most likely your leveling needs to have the bed closer to the nozzle when printing that bottom layer and this problem goes away by the 3rd layer.

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25 minutes ago, gr5 said:

So this looks like basic underextrusion - when underextrusion is on the bottom layer it's usually a leveling issue.  Notice the gaps between linfill lines as well.  

 

There is not enough filament coming out to fill in the gaps on the bottom layer.  If this is happening on every layer then you are printing too cold or too fast for your extruder/nozzle combination.  But most likely your leveling needs to have the bed closer to the nozzle when printing that bottom layer and this problem goes away by the 3rd layer.

 

I checked the level and it was too high, ie paper was wedging against the head although pretty level. So I lowered it everywhere. Result is no better. Could this also happen if I went too low? It doesn't look different. I still feel a slight tug with paper under the head.

 

I'm printing at 220 degrees C. The PLA I'm using in Inland white, rated for 205-225. Most prints come out great with no obvious underextrusion on the walls but with under extrusion on top and bottom with my typical settings.

 

I had originally attempted to print at 60mm/sec and 190C but there was lots of under extrusion all over. So I have been printing now at 220C and 40mm/sec as my standard profile. 

 

Just now I tried slowing it down to 30mm/sec with no improvement.

 

The only setting I've seen help is in Cura changing the "Skin overlap" to .2mm from 0.02. That helps blend into the walls but still leaves the bottom layer under extruded. 

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Leveling has other purposes.  The more you squish the bottom layer the better the part will stick.

 

I don't know what you mean by "leveling high" and "leveling low".  On all of my printers the bed moves and the nozzle does not but even so, many people think of it as the nozzle that moves.  Instead it's better to say "close" and "far" or "squished" or "big gap versus little gap".  high/low doesn't mean much.

 

Anyway nominal is to have things such that when Z=0 the nozzle touches the bed.  Nominal sucks.  You want to squish more than that.

 

For example if your bottom layer is sliced at 0.3mm cura will set Z=0.3mm and extrude enough for .3mm of filament.  But you want the nozzle to be closer to .15mm to .2mm so it squishes extra hard.  The worst thing is for a part to come loose 5 days into a 6 day print.  Better squish means the part sticks better.

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4 hours ago, gr5 said:

Leveling has other purposes.  The more you squish the bottom layer the better the part will stick.

 

I don't know what you mean by "leveling high" and "leveling low".  On all of my printers the bed moves and the nozzle does not but even so, many people think of it as the nozzle that moves.  Instead it's better to say "close" and "far" or "squished" or "big gap versus little gap".  high/low doesn't mean much.

 

Anyway nominal is to have things such that when Z=0 the nozzle touches the bed.  Nominal sucks.  You want to squish more than that.

 

For example if your bottom layer is sliced at 0.3mm cura will set Z=0.3mm and extrude enough for .3mm of filament.  But you want the nozzle to be closer to .15mm to .2mm so it squishes extra hard.  The worst thing is for a part to come loose 5 days into a 6 day print.  Better squish means the part sticks better.

I meant "higher" as in moving the bed higher, ie closer to the head, ie more squished. Lower is inverse.

I've never had a problem with parts not sticking. I'm using PLA. I have the opposite problem. I'm using a sharp chisel to try and get under the parts and get them off with breaking them. 

I think I originally had the bed too close/squished. Apparently material couldn't come out of the head sufficiently. Looks like the bed may not be perfectly flat, or at least the mat onto of it. I've read people suggest having a glass bed.

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