Strange first layer when slicing simple model (SolidEdge)

Hi RepRappers,

we just finished building our X400 last week and now want to get into printing. We are primarily doing engineering and now want to print out models of some of our "products".
However, the first layer of our prints are somehow strange so we had a closer look at slic3r and the visual representation in Repetier-Host. As you can see in the Screenshot ( ), the first layer has its two inner and outer perimeters - these work fine. However, the infill is only a single line of filament that does not touch the perimeter anywhere. When printing it, this line is actually so thin that barely any filament is printed at all - let aside that it won't help anything since it doesn't merge with the perimeters. The second layer and all other layers are fine and the infill of layer two and three as well as the three top layers is correct at 100% as defined in slic3r.

The model seen here is a simple test model, consisting of a square frame (width/depth 5cm, wall thickness 5mm).

Our current guess is that the STL file is not "compatible" because we are using an old version of Solid Edge (V16, 2004). When importing the model to slic3r, the following happened:

- First, there were errors about "input file has a hole near edges" and "model has overlapping or self-intersecting facets". However, it is a very simple block model so we did not know what to change. We sent the STL file through the netfabb cloud service which fixed that issue (Test_solidedge.stl)
- After that, we found out that the measurements do not match - the model would be printed smaller by factor 5 approximately. So we tried to open the STL file in SolidWorks (yet another program...) and save it from there. After that, there were no more errors and the model had the correct size. (test_solidworks.STL, resulting in test.gcode)

But now, we ran into that first layer problem described above. Could it be that the SolidEdge STL format is not "compatible" with slic3r? Do you have any other ideas what the problem could be?

The thing is that all our models were built with that version of SolidEdge so we would love to be able to take those files as they are...

Thanks for your help,
Fitsch

According to Netfabb, your model is only 1.97mm square, each edge being only 200 microns wide!

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Waitaki 3D Printer

Hi waitaki,

thanks for your help. Yes, the size issue was the first problem we encountered (I mentioned that above, but was wrong with the "being smaller by factor 5" - had the wrong numbers in my head).

However, we could open and resave that file using SolidWorks 2008 (File test_solidworks.stl) which then had the correct dimensions. But even with these correct dimensions, the first layer looks as described above, with all subsequent layers printed correctly. So we're still wondering why that first layer looks that way and if it is a problem with the original STL or something else.

Cheers,
Markus

Oh, it seems that was some kind of "file compatibility paranoia" on our side... Actually it was a slic3r settings problem.

We started off using slic3rs simple mode and loaded the configuration provided by reprap. Today I switched to expert mode, had a look at all the settings and came across Advanced -> Extrusion Width. There, the first layer was set to 150%. I set it to 100% and see - the first layer is filled correctly. I played around with that value and it works up to 147%. After that, it seems there's not enough room for the fill pattern (?). You can see the effect in the screenshot ( ) - left side, first layer extrusion width is 147%, right side 148%.

Could this be considered a bug (because obviously, the "infill" on the right image will not stick to the perimeters)?

Cheers,
Fitsch

Well, not really a bug, Slic3r seems to default to 150% - probably to get maximum adhesion of the first layer. I usually change that to 100% but tweaks are often needed depending on the model.

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Waitaki 3D Printer

Actually it's recommended that extrusion width be in the area of 210% to 240% of the layer height in order to improve adhesion between the layers - at least that's what he reprap calculator used to say. I had many problems with Slic3r, and never really used it until I changed my extrusion width to 220% and now I am extremely pleased with my results. There is the odd object where thin walls do not fill properly, but the vast majority of my objects come out with high quality.