Extrusion fail on long sides

[mcirri]

Dear all,
I am printing using a Cubex duo (with only the rightmost extruder). I have increased the voltage of the extruders to 1.6V, if I recall correctly, and installed a heated bed with a new Z level sensor.
I am using kisslice 1.5 Pro and CubeItMod605. The reason for which I am not upgrading to the 1.6 version is that when I tried I could not use the cubeitmod anymore. On top it seems like Giovanni is not supporting it anymore.
I am starting to print using the Colorfabb XT filament and, of course, I have a bit of adjustment to do.
After some playing with the finetune model I ended up with this:

Finetune

That is not perfect but acceptable enough that I went on with the print I had in mind.
After some short time I saw that the long sides of my model were all a bit irregular. There is a lot of material missing in some spot. Here is a picture of the view from top:

Long side have extrusion problems

The finetune model is added to give sense of the scale.
I also took a picture from below:

from below

I struggle to understand the issue. During the finetune I tried to lower the thickness of the slice to 0.1 but was not able to get a complete top. When trying the prism with rounded corners in order to finetune the extrusion coefficient I saw that the walls were thicker than requested.
I do not understand if it is a problem of trying to extrude too little or trying to extrude too much. Changing the speed seemed not to have an effect on this.
Here are my settings:
[Color Fabb 0.1 width 0.4]
g_code_matl=3B204D617962652073657420736F6D65206D6174657269616C2D737065636966696320472D636F64653F
fan_Z_mm=200
fan_loops_percent=100
fan_inside_percent=100
fan_cool_percent=100
temperature_C=260
keep_warm_C=150
first_layer_C=270
bed_C=100
sec_per_C_per_C=0.003
flow_min_mm3_per_s=0.01
flow_max_mm3_per_s=12
destring_suck=0.01
destring_prime=0.02
destring_min_mm=0
destring_trigger_mm=0
destring_speed_mm_per_s=100
destring_suck_speed_mm_per_s=50
Z_lift_mm=0
min_layer_time_s=1
wipe_mm=0.8
cost_per_cm3=0.012
flowrate_tweak=1
fiber_dia_mm=1.75
color=4294967040

[ColorFabb Thickness 0.1 Width 0.6]
quality_percentage=100
layer_thickness_mm=0.15
extrusion_width_mm=0.4
num_loops=2
skin_thickness_mm=0.8
infill_extrusion_width=0.4
infill_density_denominator=2
stacked_layers=1
use_destring=1
use_wipe=1
use_corners=1
loops_insideout=0
infill_st_oct_rnd=0
inset_surface_xy_mm=0
seam_jitter_degrees=45
seam_depth_scaler=0.8
seam_gap_scaler=1.3
seam_angle_degrees=180


Can anyone give me a hint to what direction this should go to try and fix?


Thanks in advance for your help,
mcirri

[frozen.rabbit]

by the looks of the print, you are printing too hot. ColorFab suggests 245-250. Your temp probe could be off from actual hot end temp. Try some test prints dropping the temp in 5-10 degree increments. Try that smaller print with 1 perimeter. If you can get that smaller piece with 1 perimeter, it should be good for the larger print with 2 perimeters.

[mcirri]

As a matter of fact I tried increasing the temperature to improve the print of the small print (the finetune.stl). I will try the other way around.

Thanks

[mcirri]

Here is some feedback. I tried the "finetune.stl" by decreasing the T. I printed it with 250°C. In order to get the border with really one loop only I had to reduce the wall thickness and that resulted in a very bad top. The sides seem to right except for the part near the tip of the shape. There some material is missing.

I will run a 240°C test next. I still do not understand what is wrong with the top surface and why.

[frozen.rabbit]

Still looks too hot, maybe some under-extrusion. A .4 noozle should be able to basically bridge across the infill. try your skin thickness at 0.3. That should give a single wall, and 2 top layers.

[EddyMI3D]

We never talked about the material you use.
What is it?

[duaneh]

This looks similar to the issue I reported (titled "Insufficient prime...", in Troubleshooting). It looks like your extruder isn't putting out filament until after the head has begun to move, leaving gaps where it starts a layer. If you have the jitter turned on so that the layer print doesn't start at the same place each time, the place where things are missing moves around.

I'm kind of disappointed that I haven't seen anyone with an idea for correcting this. Support of this slicer has been kinda hit-or-miss for quite a while now.

I am looking into a new slicer called Cura that knows about BFB printers. It will take some time to see if I can get a print out of it that will go through Cubeitmod and actually work on the Cubex; I'll post updates if things look promising.
Duane