Incomplete layers

[JCBond]

We recently built a new Voron 2.4, and for the first couple of weeks, we were printing PLA, and everything looked good. Then we started to print with ABS, and prints were not coming out as good as we wanted. In the process of fine-tuning, a defective Hot End fan caused a full meltdown of the hot-end assembly. Skipping forward, we replaced all the damaged parts and installed a new fan.

On first testing, things were looking good, but now we can print decent small parts, but the moment we try to print any surface with a longer flat layer, we get gaps in the layer.

Any suggestions?

 

[NoGuru]

Clogged nozzle, hot end fan not strong enough, extruder skipping. Take your pick and start narrowing it down. Start by trying to clear the nozzle of any clogs.
Are you running with the doors open?

 

[Sanity Agathion]

Is this ABS or PLA?

It can be either partial clog as Noguru posted above, or maybe your first layer is a bit too low judging by the roughness of surface. This can create back pressure in extruder and it does not have power to push filament through. Maybe lift it a bit higher. Or adjust flow on first layer to be a bit lower.

 

[NoGuru]

Is this ABS or PLA?

It can be either partial clog as Noguru posted above, or maybe your first layer is a bit too low judging by the roughness of surface. This can create back pressure in extruder and it does not have power to push filament through. Maybe lift it a bit higher. Or adjust flow on first layer to be a bit lower.

Good point, I do so some rough waves which means it is a little too close.

 

[JCBond]

This is printing with the following:

• eSun 1.75mm ABS+
• Hot end at 255C
• Bed at 110C
• Doors closed with chamber temps between 40 and 45C
• Part cooling fan ON
• Chamber exhaust fan ON
• Nevermore filter fan ON
• First layer Height 0.25 mm
• Subsequent layers at 0.2 mm

Also, I forgot to mention in my original post what we have already tried:

• Manually cleaned the nozzle.
• Disassembled and manually cleaned the entire hot end (Dragon HF)
• Replaced the nozzle with a new 0.4 mm nozzle
• Replaced the nozzle with a new 0.6 mm nozzle and went back to the 0.4 mm nozzle
• Replaced the Heater Cartridge (originally 45w, now 65w) and the thermistor NTC 100K 3950 on the hot end.
• inspected and adjusted the gears on the extruder (ClockWork2)
• Replaced the extruder motor NEMA 14 (originally a moons motors, now an LDO motor)
• Reflashed the latest Klipper firmware on all MCUs (Raspberry PI, BTT Octopus Pro, BTT EBB SB2240)

I am out of ideas, but I will try to go to higher layers to see if that changes anything.

 

[Sanity Agathion]

Since it's black eSun ABS+ ... have you tried:
1. incresing nozzletemp to 270 degrees Celcius?
2. Try different ABS/ASA filament?

 

[JCBond]

I have tried increasing the first layer, I have also tried going to 270 degrees, and although it seemed like I was getting better results initially, I am still having issues past the first layer now.

Increasing the temperature to 270 did improve the first layer, it was not perfect but it was better. But now that I am letting it continue I am noticing that the issue is not only on the first layer but I am getting incomplete or bad higher layers.

 

[claudermilk]

How fast are you printing the first layer? Slowing down might help.

 

[JCBond]

So it looks like the issue was our choice of HotEnd cooling fan. We had installed a Noctua fan in the print assembly, and it seems the fan, to be as silent as possible, was not providing enough cooling. Leading to a partial clog of the head as large amounts of filament were flowing all at once. We replaced the fan with a generic 24v fan and the issues seem to have cleared.

 

[Sanity Agathion]

So it looks like the issue was our choice of HotEnd cooling fan. We had installed a Noctua fan in the print assembly, and it seems the fan, to be as silent as possible, was not providing enough cooling. Leading to a partial clog of the head as large amounts of filament were flowing all at once. We replaced the fan with a generic 24v fan and the issues seem to have cleared.

Honestly that does not surprise me at all. Noctuas are silent - at the expense of airflow. That's a known, and in VORON community their use is discouraged.

Glad it works for you now, hopefully it will stay that way!