Harmonic Vibration?
Is harmonic vibration an issue with 3d printing?
I searched here and found nothing. A google search showed a little talk on a Lulzbot forum.
I was printing this...
https://www.thingiverse.com/thing:919475
The first time I printed one, I sliced using simplfy3d (Slic3r has a weird result when slicing), and I used a 20% infill with a 20mm raft. It printed just fine. So I tried again (a few weeks later) and for the last three days I have tried printing another with a 10% rectilinear infill with a 30mm raft. Twice it failed in nearly the same point about halfway through the print (while I was sleeping). The model would fall off the build plate and the printer began making angel hair pasta both times.
Today on the third attempt I timed the print so it would near the halfway point when I woke up. I found that the printer was making a plastic sounding rattling noise as it was nearing the same halfway point of the model. The sound appeared to be coming from the model itself even though there is no moving parts (so I am not sure what could be rattling). I slowed the print speed down to 90% using the menu on the printer and the rattling noise went away.
I am guessing now that the prints falling over and failing was a result of some harmonic vibration as the model hits the perfect density and height to maximize vibration in the model itself. This vibration then causing the adhesion on the build plate to fail and the model falls over.
Is this even remotely possible??? What can I do to mitigate ALL possible harmonic vibrations if this is in fact true?
Re: Harmonic Vibration?
I am convinced it is true: Harmonic vibration is a thing in 3D Printing.
Or call it increased vibration at resonant frequencies. leading to rough surfaces in long thin vertical walls or loss of adhesion from the buildplate. I see it occasionally in my own prints, especially in rapid short moves when its "stitching things together like a sewing machine". Every now and then you run into a part where you think the printer is gonna fall apart. As you already said, reducing the speed a bit changes frequency and usually helps.
Or it could be curling and the nozzle rumbling over the last layer. Printing slower or increased cooling or using z-hop might help there