Optimize a (almost) perfect first layer

Bambu Lab X Series Bambu Lab X1C
1

Hi

Actually my Bambulab X1 prints PLA flawlessly, including the first layer. I never had trouble with the first layer (cool or hot plate).

Recently, I tried to write on the first layer with a marker. Even though the layer looks perfect, writing on it looks horrible.

Here is how it looks like:

PICT0119
PICT01191920×1440 210 KB

Seems like a capillary effect caused by the small gap between the extrusion lines.

Here is how it looks even closer:

PICT0118
PICT01181920×1440 302 KB

I took orca slicer and I tried to optimize it. I played with flow for first layer (up to factor 1.25) and width of the extrusion line.

I was able to reduce the effect, but not completely avoid it.
The gaps happen even with some significant overextrusion, which I don’t really understand.

Is it possible to get a first layer completely without any gaps between the extrusion lines?

It’s clear, that we are talking about the last % of optimization. As long as I don’t try to use markers, everything is fine :wink: Still, I would really appreciate to find a solution.

2

In a word, I suspect “no” and the reason why 3d printed objects shouldn’t be used for holding or storing food, as bacteria can always get in between those gaps. I’ve found mold also tends to grow on 3d printed parts that come in contact with water.

3

If you are marking the top surface you might try ironing.

Or find a different marker, something less of a liquid that will not run…

4

That looks intentional to me like there’s a problem with the model. What does the sliced preview look like?

5

The top surface is no problem at all, even without ironing. It is not a problem of the model. It only happens on the first layer…

The image is taken with a microscope, the gaps are very small.

6

Slow down the first layer speed and try increasing the K value by +.007 (ie K .02= K.027) and don’t use the LiDAR when sending the print

7

I have already reduced first layer speed to 15mm / s, but I have not tried yet changing the K value.

How does it differ from changing the flow rate with a constant factor (in orca
slicer)?

8

I don’t use anything but Orca, but I know that the default calibration K value in the calibration test tells you to look for the “perfect” look, but that’s not what you are wanting you want a better squish to seal the downwards C gapping in a physically OD perfect print, so if you increase that volumetric rate and rerun it I think you’ll see the change you want.

9

In orca slicer there is a setting called “bottom solid infill flow ratio”.
I changed that up to 1.25.
This should have the same effect as changing the K value but only for the bottom layer, no?

As I wrote in the initial post, there were still some gaps between the lines even though there was singificant overextrusion.

10

Take a look at the Elephant foot compensation settings on the Quality tab.

11

Don‘t see how the elephant foot compensation is related to my issue?

12

Very interesting topic. I have these “problem” too. If I use a smooth plate wit my P1P I can see this little gaps. I’ve tried to increase the flow, changed the K value and also configured the “Textured PEI Plate” in Slicer, because this brings the nozzle a little bit lower to the plate. Nothing helped. :slightly_frowning_face:

13

If overextrusion does not close the gaps, it might be caused by the geometry of the nozzle and the dynamics happening when new molten material leaves the nozzle?

I changed the line width from 0.3 up to 1mm (standard is 0.5 for first layer). For line width >0.4mm the gaps start to become larger. When reducing to 0.3mm, the gaps become smaller (but not 0). Due to the capillary effect (i suppose), the situation gets even worse when the gap is reduced.

14

Ok, after some testing I found some settings, which produce good results:

Use Hilbert Curve for the bottom layer and increase bottom_solid_infill_ratio in orca slicer to 1.2.

This looks like that:

PICT0122
PICT01221920×1440 164 KB

There are still some gaps, but writing on the surface is ok :slight_smile: