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Can you help me identify the artifacts in my prints.

Posted by voyager 
Can you help me identify the artifacts in my prints.
June 14, 2019 07:07AM
Hey guys,

I spent the last 3 months building the BLV MGN cube and it just prints horrible.
I have build around 30 printers, but this is the first one I can not get right, and I can not identify the problems.

About the printer :
24 volt system core XY
It uses 5 MGN rails, parts a printed 80% infill in ASA.
X-Y motors nema17 0.9 per step Z motors nema17 1.8 per step
Duet wifi clone, tested next to a original one, behaviour is the same.
Geared nema 17 as extruder, steps per mm are calibrated.
V6 clone but with original E3D nose, heater and temp sensor.

Printer

And well this is what I get.

Picture1

Picture2

For me this screams over extrusion and a very bad part cooling fan.
Reducing the flow to 80% will solve some of the problems and we get this

picture3

I have wavy lines al over my prints and I don't know why.
They seem to be oscillations produces by the mechanism but I can not feel or hear them during printing.

Cooling

This is the cooling and used a 5015 radial fan @24v
For me this just looks wrong, its way to high up and the 5015 fan does not move enough air to do its job.
I use the tech2c cooling for my p3steel my hybercube and hypercube evo, and it works perfectly.

What I want to know, does this partcooling fan look right to you? It looks like its cooling the heater block more then the print it self.
Negative overhang in prints the wavy effect gets much worse.

I welcome any ideas you have.
Re: Can you help me identify the artifacts in my prints.
June 14, 2019 08:10AM
I think this is called 'Salmon skin'. Are you by any chance using DRV8825 stepper drivers?


http://www.marinusdebeer.nl/
Re: Can you help me identify the artifacts in my prints.
June 14, 2019 08:57AM
No the duet uses TMC2660, however the motors hiss like a 8825 with to high current setting.
They are set to 1.1 amps and still produces noise, when idle.
Re: Can you help me identify the artifacts in my prints.
June 16, 2019 01:19PM
Maybe the current is still too high, did you try lower like 300 to 500mA or does it skip? It could be that the stepper motors step too aggressively and wobble around after doing a full steps worth. Mine does this too to some extend but not nearly as pronounced, and I'm using NEMA23 steppers. It could be the momentum of the mass.
Another possibility is that toothed pulleys may give an uneven motion when the belt is looping around it. Try rotating the belt or use smooth or larger pulleys.


--
Kind regards
Imqqmi

NFAN CoreXY printer:
[reprap.org]
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