Weird ghosting effect in prints

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Weird ghosting effect in prints

Postby Bellus » 2015-Jan-Thu-23-Jan

A bunch of my prints have plagued with this "ghosting effect". It seems to be more prevalent around curves/edges. ImageImageImage

Regardless of the filament brand or speed it still happens. I am currently printing at 35-20mm/s for everything. I have checked the calibration of all motors/axis. I am pretty sure I have some ribbing and z wobble, but would that also cause this as well?


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Weird ghosting effect in prints

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Re: Weird ghosting effect in prints

Postby thawkins » 2015-Jan-Thu-23-Jan

Its called "ringing", and its caused by running the print too fast or with too high an accelleration. The reason why its occures close to one side of corners is because the printer is struggling to cope with the rapid change in direction, caused by the mass of the print arm and head suddenly trying to move in a completly different direction. The head "oscilates" around its ideal position as it overshoots then undershoots the correct position. Eventualy the oscilations damp out and the wall becomes smooth again. One trick is to run the outer perimeter very slow, but have inner perimeters and infill rendered fast. That way you can have a reasonably fast print time, but have a slow outer shell print to avoid visable artifacts like this.

It can also occure at quite low speeds if you have significantly increased the mass of the printhead, things like extra fans, extruders, lights, camera mounts etc, all add to the mass of the head.
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Re: Weird ghosting effect in prints

Postby Bellus » 2015-Jan-Fri-00-Jan

I am currently using Cura at the moment, those pieces were printed 30mm/s for everything. I don't think I have added any mass to the printer head, just your standard stuff, with exception of a motor fan and shroud. I would be willing to bet it is the acceleration speed. That is the only speed I have not adjusted, mainly cause if I knew how to change it I wouldn't even know what a decent setting would be. I will have to also try out the outer slow inner fast technique as well.
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Re: Weird ghosting effect in prints

Postby orangefurball » 2015-Jan-Fri-05-Jan

Just adjust the acceleration in Cura down a bit until it goes away, remember the stock value though.

I haven't messed with trying to get rid of this on my bot, but adjusting the acceleration is only a few clicks in Cura.
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