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Solid layer really sparse and partial

Posted by barakori 
Solid layer really sparse and partial
November 17, 2014 02:25PM
I'm trying to print a part that has some solid surfaces a bit above the ramp. Here's what should be printed at 3.60mm (taken from the Gcode view in pronterface):

In reality I got something that's not solid at all (I'm mostly talking about the middle part):

Notice that the two solid parts on the sides are better (but not great), and instead of a solid middle section, I got really thin strips of filament. After I stopped the print, I tried extruding 10mm of filament, and it came out fine, measured at 0.35mm using a caliper.

Any thought on what may cause this? I looked at the pictorial troubleshooting guide, and didn't find anything similar.

Re: Solid layer really sparse and partial
November 17, 2014 06:09PM
Looks like you're under-extruding. Have you calibrated e-steps per mm and checked your extruder isn't skipping steps?

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Re: Solid layer really sparse and partial
November 18, 2014 11:39AM
You need to do 3 things:

1 lower your speed.
2 Increase temperature.
3 add more solid layers.

When you are doing solid layers on top of a such structure, you need to slow down to allow the filament to stick to it, increasing the temperature will allow the filament to flow easier and usually you will create a solid enough net to fully close the top after 3 layers, so use at least 6 to 8 solid layers on top that way if any imperfections after the first 3, the other 3~5 layers will do the job.

Not related but from the picture, you need to increase you retraction settings.
Re: Solid layer really sparse and partial
November 18, 2014 03:16PM
Thanks for the comments.

I checked the extruder, and extruding 100mm at 30mm/min resulted in 97mm of actual extruded filament. While this is not perfectly calibrated, it seems to be close enough not to be that bad.

I'm currently printing at 40mm/s (normal speed) with PLA at 185C hotend and 60C hotbed.
My retraction settings are 4.5mm at 30 mm/sec.
@ggherbaz, what retraction / speed / temp do you recommend I try?

My only problem is that the printer printed quite good just the night before - here's what I printed:

What I don't understand is what could have changed in 24 hours. Any advice and tips are welcome.

Thansk again.
Re: Solid layer really sparse and partial
November 18, 2014 05:05PM
Tried to simplify the case here, so I printed a 25x25mm cube, and stopped the print just before it finished the 2nd layer. Here's what I got:

Each layer has 3 perimeters. They seem fine. Using a caliber, the 3 perimeters are 1.2mm wide, and that matches the print setting for 0.4mm width (Slic3r 1.1.7)
The diagonal lines in the picture look like wide lines with gaps. Actually each diagonal line is two lines (back and forth). I checked, and indeed 10 visible lines (20 actual lines) are 8mm in width, but the are a lot of gaps. Basically (to the bast of my caliper capabilities) each two lines are 0.7mm wide with an extra 0.1mm gap.

Since I don't see filament going somewhere (the bulge towards the top is where I stopped the print), I must be extruding less plastics on the diagonal lines than on the X/Y lines, but why?
BTW, this was done in Slic3r, I also tried similar settings in Cura, and got really bad results.

Please advice...
Re: Solid layer really sparse and partial
November 19, 2014 12:00AM
Since your steps per mm are not correct use extrusion multiplier to compensate for (1.03)
Temperature: 195 - 200
Speed: 20 - 30 mm/sec.
retraction 4mm at 4600 for direct drive (use less speed for geared) for Bowden systems increase to 6 - 7mm.
Nozzle: 0.4 Extrusion Width 0.48, Nozzle 0.3 Width 0.36 Nozzle 0.5 Width 0.6 if you make your width same as you nozzle be sure to use lower layers to compensate, the gaps you have are the result of a non compressed layer (round instead of oval)

Edited 1 time(s). Last edit at 11/19/2014 12:02AM by ggherbaz.
Re: Solid layer really sparse and partial
November 22, 2014 02:19PM
Tried with slic3r with the following settings:
Extrusion multiplier: 1.03, temp: 190C (+5 from pervious).
Extrusion width: 0.42 (I have a 0.35 nozzle) and 0.15 layer height.
Speed: 30 for perimeters and small perimeters, 80% of that for external perimeters.
Other speeds are 40-50 (where the recommended/defaults are 50-60).
Retraction 7mm (I misread the reply).

The results don't look much better:

Some of the holes on the two horizontal areas are intentional (two screw holes), but the rest is simply not solid enough. I'm using 3 solid layers (top and bottom).

Also, during the print I took this picture:

The middle "box", which is support, is really messed up. The outside is fine, but all the material inside just isn't laid out properly.

At that point, I thought this might be because I don't have a fan and saw that fan for PLA is recommended. The prints above are actually for a fan holder. Once it finished, I attached it to the print head and repeated the print:

The result is somewhat better (notice the top melted part is similar, but much smaller). Still, there are gaps in what should be horizontal surfaces.

Anything else I should try? I don't want to lower print speed even more, it would take too much time to print anything.

Re: Solid layer really sparse and partial
November 22, 2014 05:05PM
Set your extrusion width down to 0.35, same as your nozzle diameter, you may need to reduce the extrusion rate a little, but you will get much better results from slic3r.
Re: Solid layer really sparse and partial
November 24, 2014 02:27PM
I started with 0.35 width prints, when this didn't work out @ggherbaz proposed printing at 120% of the nozzle width, which didn't work our as well.

We've come full circle :-(

I'm seeing a strange phenomena that makes more sense to describe in a different thread.
Let's leave this one unsolved...
Re: Solid layer really sparse and partial
November 26, 2014 10:38PM
You probably misunderstood me, I didn't told you to print at 120% nozzle width, when you mention that your steps per mm were wrong I told you to compensate it with "extrusion multiplier" and it wasn't 120% was 1.03 instead of 1.0. on the nozzle width a 0.42 for a 0.35 size nozzle is the standard.

If you were trying to print at 120% width most likely your extruder was pushing too much filament.

For what I can see from the photos, you went from little extrusion to over-extrusion. you need to find the middle.

Edited 1 time(s). Last edit at 11/26/2014 10:41PM by ggherbaz.
Re: Solid layer really sparse and partial
November 27, 2014 07:43PM
Thanks @ggherbaz,

I was extruding at 1.03 multiplier (as you said).

You also said: "Nozzle: 0.4 Extrusion Width 0.48, Nozzle 0.3 Width 0.36 Nozzle 0.5 Width 0.6...", which I shortened to width = 120% or nozzle size, I put 0.42 in my settings (because I have a 0.35mm head).
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