No solid top and bottom layers

I'm pretty new to 3D printing but I'm making progress.

I have my printer setup and printing pretty well, but I have one issue.

When I create an object in FreeCAD, export it to an STL, slice it with slic3r, and print it, the top and bottom layers are not solid, they are the infill pattern. The attached CAD picture is what I expected the part to look like. The other picture is what I got. You can see the solid perimeter on the outside and inside, but there was not solid layer on the bottom or top. The recessed part in the middle should be half the depth of the part. As you can see, the middle area is all crossing infill with no solid layers at all.

The part is supposed to be 25 MM x 25 MM x 5 MM with a recessed area of 15 mm x 15 mm x 2.5 mm.

I cannot find any settings in slic3r to control the top and bottom of a part. I would think those are considered perimeters, but it's not treating them that way.

I also attached the STL and gcode files to this message.

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3D Printer: Reprap Original Mendel with RAMPS 1.4 electronics, j-head MK V-BV 0.4MM extruder, Wade's geared extruder, setup for 1.75MM filament

Your model is the problem, not the slicer.

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Waitaki 3D Printer

I have no idea how you did this in FreeCAD (or indeed how you even sliced that .STL file!) but is this what you're trying to do?:

I tried that model. It seemed to have a bottom, but no solid top layers. When I look at my print closely with a magnifying glass, the diagonal strands have gaps between them that is wider than the strands. It looks like the top layer is about 40% instead of 100%. I'll export my slic3r config and attach it as a text file.

I do actually think the issue is the model, not slic3r. I've downloaded a couple of STL files from Thingiverse and they slice and print fine. There is something about objects I create in FreeCAD that are not working correctly with slic3r.

Edited 1 time(s). Last edit at 08/13/2014 10:07AM by EmailGuy.

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3D Printer: Reprap Original Mendel with RAMPS 1.4 electronics, j-head MK V-BV 0.4MM extruder, Wade's geared extruder, setup for 1.75MM filament

My model was generated in OpenSCAD, not FreeCAD. If you're saying that this still slices and prints without top layers then it's not FreeCAD.

I am not sitting at my printer at the moment so I can't double-check, but am I missing something in your config - why are all the extrusion width parameters set to zero?

The default for those are all set to zero. When I look at the default print profile, under advanced, extrusion width, the only non-zero value is the first layer setting. It defaults to 200%. I actually changed that to 0 since I didn't want a super thick first layer. I have not made any changes directly to the ini file. I simply took the default settings and made a couple of changes. Here is what I changed from the default.

For the filament, I added a new profile called white PLA. I measured the actual filament I'm using and it was 1.66 MM, so I set it to that. I also changed the temperatures for the first and subsequent layers to 185C.

For the print settings, I changed the layer to .25 MM for better quality and the first layer height I set to .35 MM. I set the top and bottom solid layers to 5 instead of 3. I also set it to do three loops at the start to make sure the PLA is flowing well before it starts printing the object.

I think everything else is pretty much at the defaults.

Edited 1 time(s). Last edit at 08/13/2014 12:00PM by EmailGuy.

Quote
EmailGuy
I cannot find any settings in slic3r to control the top and bottom of a part. I would think those are considered perimeters, but it's not treating them that way.

Go to "Print Settings" tab then the item "Layers and perimeters". You will see a section called "Horizontal shells". This allows you to set the number of solid layers that will be printed on the bottom and top of the part. If either is set to 0 then the top or bottom outer layer will be printed with infill.

Dave

I increased the solid top layers from the default of 3 to 5 and it didn't make a difference.

It actually works fine with STL files I download from thingiverse. It messed up with the STL I created in FreeCAD and the one QuackingPlums created in OpenSCAD

Ok I just checked and zeroes mean "auto" in Slic3r-speak so that should make Slic3r calculate what it thinks is the best extrusion width - there is some debate about how good this is but let's assume this is fine for now since you are slicing/printing thingiverse files successfully.

When I tried to slice your original file Slic3r complained about it being non-manifold (a common problem with CSG modeling) - I was wondering if the lack of shells was due to Slic3r somehow 'fixing' it wrong, which is why I created a copy using OpenSCAD (I always incorporate a CSG fudge factor to prevent this issue). My corrected .STL slices fine with no warnings, but if you are still not getting horizontal shells then this indicates that there is another problem.

Things I would look at (in no particular order):

• Different version of Slic3r - I use 0.9.9 because every later one I've tried has broken something new. I know this slices fine on mine.
• Is the "solid infill every 10 layers" setting a default? It's set to zero on mine. Could it be that Slic3r is miscalculating whether it's a solid layer or an infill layer?
• Is the PLA extruding smoothly when it's first laying down the skirt? How accurately have you calibrated the bed?

I'm running out of ideas to be honest. The fact that other objects from thingiverse (presumably more complex ones!) actually slice and print fine makes it even more infuriating that a simple subtraction of one cube from another is causing such wildly wrong output.

I'm using the latest version I found (1.0.0RC2). I'll look for 0.9.9 and try that.

Now I get an error whenever I load an object. See the attached screenshot.

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3D Printer: Reprap Original Mendel with RAMPS 1.4 electronics, j-head MK V-BV 0.4MM extruder, Wade's geared extruder, setup for 1.75MM filament

I completely uninstalled the 1.0.0RC2 version of slic3r and installed the 0.9.9 version. I deleted the configuration files so that it would go through the first time setup wizard again.

I sliced the corrected model that QuackingPlums uploaded and I still have the same issues. No matter what I set the numbers to for the solid top and bottom layers, it only does one layer. I selected concentric for the top/bottom fill patterns and rectilinear for the fill pattern. If you load the gcode into pronterface and look at the layers, you can see only one layer for each top surface and one for each bottom surface are concentric. The rest are the 45 degree diagonal patterns of the rectilinear. Take a look at the gcode.

I'll try the newest slic3r and see if this is a bug that has already been fixed.

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3D Printer: Reprap Original Mendel with RAMPS 1.4 electronics, j-head MK V-BV 0.4MM extruder, Wade's geared extruder, setup for 1.75MM filament

Ok let's deconstruct what's happening here; pasting the header from your gcode for reference:

; generated by Slic3r 0.9.9-dev on 2014-08-14 at 14:28:52

; layer_height = 0.25
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.4
; perimeter_speed = 30
; infill_speed = 60
; travel_speed = 130
; nozzle_diameter = 0.5
; filament_diameter = 1.66
; extrusion_multiplier = 1
; perimeters extrusion width = 0.84mm
; infill extrusion width = 0.84mm
; solid infill extrusion width = 0.84mm
; top infill extrusion width = 0.84mm
; first layer extrusion width = 0.60mm

Notice that your (presumably auto-calculated) extrusion widths are all 0.84mm except for the first layer, which is 0.60mm - this sounds high to me. The Tantillus calculator suggests that extrusion widths should be 0.59mm for your nozzle/filament combination. Even at W/H ratio of 2.5 for ABS the figure only comes out at 0.63mm - I have no idea if Slic3r's numbers are valid but I get better quality prints using either of the two methods I just mentioned to calculate my extrusion widths.

So anyway, as a result of your configuration your gcode is as follows:
Layer 1 is solid, concentric, at first layer extrusion width of 0.60mm
Layers 2 and 3 are solid rectilinear (I don't know if this is a bug, but this happens for me too) with 3 perimeters, at perimeters/infill extrusion width of 0.84mm - it's solid so it's kinda right.
Layers 4 and 5 are 40% rectilinear infill with 3 perimeters.
Layer 6 is interesting - it appears to be a REALLY high density solid infill layer.
Layer 7 is back to 40% rectilinear infill.
Layer 8 is another super-dense solid layer like layer 6.
Layer 9 is solid rectilinear.
Layer 10 is solid concentric (we are now at 2.5mm height, so this is the bottom of the recess).
Layers 11 to 20 are all the same and consist solely of 3 inner and 3 outer perimeters at 0.84mm extrusion width (0.84 * 6 = ~5 so you have no room left for infill).

I suspect that Slic3r has set your extrusion width too high and your nozzle can't create a line that wide, causing gaps to appear in every layer except the first one (which inexplicably does have a valid extrusion width set).
The photo of your printed part certainly appears to backup this theory that it's an extrusion related issue.

Can you manually set all of your extrusion widths (Configure>>Print Settings>>Advanced>>Extrusion width panel) to 0.6, then try to slice again? I've attached my sliced output using these settings and you can also compare the headers here:

; generated by Slic3r 0.9.9 on 2014-08-15 at 00:21:51

; layer_height = 0.25
; perimeters = 1
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.4
; perimeter_speed = 40
; infill_speed = 40
; travel_speed = 130
; nozzle_diameter = 0.5
; filament_diameter = 1.66
; extrusion_multiplier = 1.0
; perimeters extrusion width = 0.60mm
; infill extrusion width = 0.60mm
; solid infill extrusion width = 0.60mm
; top infill extrusion width = 0.60mm
; first layer extrusion width = 0.60mm

You should now see that the perimeters and solid layers are much closer together, leaving room for infill around the recess.

If this is indeed the problem then how you manage to slice other parts off Thingiverse with these settings and print them at satisfactory quality confounds me!

I changed my extrusion width to .59 and made one pretty decent print. Now I seem to be having a problem with my nozzle clogging up. After I can figure that out, I'll try again.

I think setting the width manually was a big part of my issues. It appears slic3r wasn't calculating it correctly when left to the default of zero.

When I last used the "concentric" feature, it only printed the bottom and top layers concentric, and other solid layers remained rectilinear - so I think that must be how it is designed to work. Which makes sense because it is only to improve the aesthetics, and only the outside layers are required for that.

Dave