Gaps between solid infill

[Cael Fahnestock]

I've been having this problem for a while now and can't seem to fix it. On the first layer, the printer seems to under extrude, leaving gaps between the solid infill lines. That is, the individual lines of plastic don't even connect. The gaps disappear on the second layer. Every layer afterwards, the extruder seems to over extrude. By the 3rd or 4th solid layer, plastic is catching on the extruder tip and the extruder is leaving ridges on the surface. I've tightened and loosened the strings, adjusted the Z height many times, re-flashed firmware, experimented with different layer heights, tried cura and slic3r, but nothing seems to fix the problem. Help would be GREATLY appreciated.  

[Bob Wood]

Cael, Can you post your slicing configuration file?

[Cael Fahnestock]

Here's the attached the config.ini file

[Bob Wood]

These are the ones I would change to start with

first_layer_extrusion_width = 200%

first_layer_height = 0.3 

please note I attached my config file for reference

[Cael Fahnestock]

I'm still the seeing the same results. 

[Bob Wood]

Hmmm..I would expect to see different results. Can you post the g-code file?

[Cael Fahnestock]

sorry this is the correct one 

[Bob Wood]

I do not see anything that would cause the issue, but I may of missed something. Is this issue on every model? Is it possible that the first layer is printing too close? Is the extruder stepper motor driver gear slipping?

[Cael Fahnestock]

Yes, it happens on every print. I've calibrated the nozzle (if that's considered "leveling the bed") many times but I'm not seeing any improvement. In the assembly guide, you have listed 2000 mm/s^2 as a good starting value for the X/Y acceleration. However, in my EEPROM settings, the X/Y acceleration values are only 200mm/s^2. I'm wondering if thats a problem and if there are any other errors in my EEPROM settings.

[Bob Wood]

XY acceleration is set at 200, but I do not think that this would be the issue. What do yo have the steps/mm set on the extruder? It should be 164.7.

I will try to get some time to run your file and see what happens. It seems like it might be an extruder issue or somewhere in the extruder drive system.

[G Fischer]

I had a similar experience when I first built my machine. Question: are you using the clear feed tube or are you using the teflon (white) feed tube? My problem went away after I went to the teflon because the filament was to tight in the clear tube causing restricted flow. Just a thought.

[Cael Fahnestock]

The E steps are 164.7 and I'm using the clear feed tube. I set the first layer extrusion width to 100% and calibrated the nozzle again which somehow managed to rid of the large gaps in the bottom layer. But the layers continue to gradually over extrude. The layers after the first layer seem to have thicker solid infill lines than the first, causing the solid infill lines to squish together.

[Bob Wood]

PM Sent. The PTFE tube is a lot slippery and might make a noticeable improvement.

[Cael Fahnestock]

Im still experiencing over extrusion. However, the first layer is now almost perfect.  The layers afterward continue to over extrude, more so in small areas.

[Bob Wood]

Cael,

Can you please post pictures?

[Cael Fahnestock]

[Bob Wood]

Cael,

It looks like it maybe over extruding. Can you try changing your nozzle size to 0.5 mm ad see what happens?  It is hard to tell from a picture, but it looks like the first layer is not "squished" at all. You might try lowering the first later is you change the nozzle size in the slicer configuration.

Has anyone else in the forum see this or have any ideas?

On Wednesday, May 18, 2016 at 5:22:28 PM UTC-5, Cael Fahnestock wrote:

[Jeff Tapia]

I'm with bob on the first layer needs to be calibrated closer to the bed.

Before the 0.5 nozzle I would try keeping the 0.4 millimeter nozzle and changing the  Repetier extruder flow setting from 1.0 to something like 0.95 or 0.90 but first recalibrate your first layer.

Sincerely, Jeff Tapia

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[Dan Keller]

Yet another thought, and please let me know if I'm off.

What I find intriguing is the progressive nature of the issue. Ordinarily, I would expect things to either go from too little infill to perhaps eventually normalizing or to start out squashed and eventually normalizing. Here's my personal experience:

• When I initially had my head calibrated, it was too close to the bed. First layers were "squashed" and the head was dragging over the PLA. After several layers, the print got better, eventually turning out good layers one after another.
• When I re-calibrated, I got the head a little too far. This resulted in the first layer looking a bit "loose" (but not quite "under extruded") with each subsequent layer getting better until it just looked good overall.
• Finally, when I got the first layer perfect, all layers looked uniform.

What I think is interesting is the layers don't follow any of these patterns. It seems initially like my second scenario - first layer too loose with things filling in on subsequent layers. However, instead of normalizing so that layers eventually turn out uniform, it seems like they get progressively more squashed.

Could it be that this is a two-fold issue: first layer is "loose" due to the head being just a little too high followed by the Z movements being just a little too small, meaning layers get progressively more squashed?

Let me know if my explanation doesn't make sense.

[Cael Fahnestock]

The first layer was indeed too far from the bed, I'm still not sure why I'm continuously having to calibrate the Z length. Changing the nozzle size did not solve the problem and adjusting the flow rate only delayed the over extrusion. I would expect the gradual over extrusion to be a result of the Z moves being to small, but it's not. If I have all layer heights set to 0.2mm and I stop a print on the 6th layer, the nozzle is correctly 1.2mm above the print bed. I've noticed that when I'm printing with the bottom layer extrusion width set to 100%, the second layer and so forth somehow have thicker extrusion lines than the bottom layer. Shouldn't a 100% bottom layer extrusion width match the other layers?

[Bob Wood]

Have you tried a different model or a different slicer? I am not having any luck trying to produce this result.

Maybe the z-axis is doing something weird. Are the Z motors cold or hot? Maybe the Z axis is missing steps? You might check to make sure the couplers are not slipping.