Proof of Harmonic Vibration/Resonant Frequency problem
Last week I posted a question about issues with Harmonic Vibrations (aka Resonant Frequency vibrations) being an issue with the MK2s. I only got one response with the same "suspicions" that I had, but nothing concrete.
After 3 of the same models all failing at nearly the exact same point, I printed a fourth and trained by IP security camera to capture the print and see what was going on. The model is the millennium falcon. Sliced with Simplify3d with 30mm raft, 10% infill, (this print was honeycomb) but I have had the same failure with another infill pattern.
As you should note, at the 30 second point in the video, the extruder begins to shake somewhat violently. You cannot see it well in the extruder itself, but if you will watch the shadow on the wall behind the printer, you can see it very well. The shaking happens on the next layer also, but not quite as bad. Both of these cause irregular filament buildup on the model which is then struck by the nozzle causing the model to fall over.
This happens exactly the same way on 4 attempts. On one attempt I even slowed the print down on the MK2 menu to 90% but the same problem still occurred. I figure that if I add more infill to add more weight to the model I can probably change the "resonant frequency" and finally get a successful print of this model. VERY INTERESTING!!!
Bill
Re: Proof of Harmonic Vibration/Resonant Frequency problem
are you sure that this "violent shaking" of the extruder isn't caused by the use of the "Retraction vertical lift" option inside the Extruder tab of S3D ?
and by the way: it's a very challenging approach to print an object that tall with only a small raft at the build plate. no question that it tends to resonate.
dem inscheniör is' nix zu schwör...
Re: Proof of Harmonic Vibration/Resonant Frequency problem
are you sure that this "violent shaking" of the extruder isn't caused by the use of the "Retraction vertical lift" option inside the Extruder tab of S3D ?
and by the way: it's a very challenging approach to print an object that tall with only a small raft at the build plate. no question that it tends to resonate.
I guess it is a possibility that the combination of retraction, the model, and the printer all contribute to the resonance. If it were just the retraction, I would think the shaking would occur throughout the entire print. I have printed this model before with a smaller raft, but I think the infill percentage was different. I had hoped to try and print the model with slic3r to change the variables in the print settings. But, slic3r cannot handle the model. When I load the stl model the preview in slic3r shows a bunch of holes and missing details in the model. I sliced it anyway but I previewed the gcode file using an online tool and the holes and missing detail remained so I did not print. For some reason slic3r cannot handle the model. If you or anyone else could try and load the model I would appreciate any advice on making it work with slic3r without loosing the fine details of the model.
The model is attached to this message...
Re: Proof of Harmonic Vibration/Resonant Frequency problem
hmmm... I think that is the model they made for printing with the "Da Vinci 1.1 Plus" and that you can find here at thingiverse.
its an fdm printer as well, but with a different design. the build plate doesn't move in y direction there (only in z), so the whole extruder needs to move in x and y direction.
I guess to print this in the given orientation, you need to slow down the y-acceleration (not only the speed) severely to avoid the model falling over, sooner or later.
maybe it's a little bit more stable, if you rotate it by 90° in z direction.
furthermore it has many details as overhang, so bridging might be a problem as well...
very challenging to start 3d printing with...
dem inscheniör is' nix zu schwör...
Re: Proof of Harmonic Vibration/Resonant Frequency problem
The model I am using is actually from this model of the falcon.
Pardon my ignorance here, but how does the model being made for the Da Vinci 1.1 Plus make a difference? Is a model not just a model? I would think the real difference, as it relates to printer, would be set in the profile of the slicing software. Or, am I missing something?
Also, do you have any idea why the model in the post is not properly handled by slicer. When I slice the model this is what it looks like in slic3r. In simplfy3d it slices just fine.
Re: Proof of Harmonic Vibration/Resonant Frequency problem
I don't think there is a problem with the model or printer: http://shop.prusa3d.com/forum/hall-of-fame-best-3d-prints-f15/millennium-falcon-on-the-mk2-t1065.html#p7967
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Proof of Harmonic Vibration/Resonant Frequency problem
...
Pardon my ignorance here, but how does the model being made for the Da Vinci 1.1 Plus make a difference?
...
just wanted to point out that the Da Vinci 1.1 Plus has a different design that couldn't lead to such a resonance phenomen that you've assumed / mentioned.
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Is a model not just a model?
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yes, but with some printer designs you can print a model perfectly, with another one you can't.
but as you can see from the other posts: the model seems to be successfully printable with the i3 mk2.
even so that it's a slightly different model (without the satellite dish).
dem inscheniör is' nix zu schwör...
Re: Proof of Harmonic Vibration/Resonant Frequency problem
The reason Slic3r isnt slicing it properly is because the mesh is 'broken'. Its not manifold (watertight), it has literally, 100's of thousands or errors. Cura does seem to manage to slice it (and S3D from what you say), but I couldnt even fix it in Meshmixer.
Fortunately, someone else fixed it for you: https://www.thingiverse.com/thing:2338105
As for the vibrations; are you using anti vibration feet by any chance?
Re: Proof of Harmonic Vibration/Resonant Frequency problem
The reason Slic3r isnt slicing it properly is because the mesh is 'broken'. Its not manifold (watertight), it has literally, 100's of thousands or errors. Cura does seem to manage to slice it (and S3D from what you say), but I couldnt even fix it in Meshmixer.
Fortunately, someone else fixed it for you: https://www.thingiverse.com/thing:2338105
As for the vibrations; are you using anti vibration feet by any chance?
Not yet... That was my next method of attack. Trying to decide what anti-vibration method to use.
I got the print to work without any modification (infill, etc.) by turning the model 90 degrees on the Y axis. Turned out darn nice!
Re: Proof of Harmonic Vibration/Resonant Frequency problem
I asked because feet are more likely to make problem worse, rather than solve it. They do work to reduce noise, but can exacerbate resonance issues
Re: Proof of Harmonic Vibration/Resonant Frequency problem
I asked because feet are more likely to make problem worse, rather than solve it. They do work to reduce noise, but can exacerbate resonance issues
I am glad you mention that. I suspected that might be the case and I was reluctant to use the feet for that reason.
I am leaning toward a rubber mat. I have one in front of my sink that is about an inch thick and is pleasant to stand on. I thought about getting another and cutting it to size.
Re: Proof of Harmonic Vibration/Resonant Frequency problem
I just picked up some thick and heavy sound insulating foam.
I intend to enclose my printer, and will use that foam on the inside. Seems to work pretty well as a base too. i'll wait a few days before recommending it though; I tried some softer foams before (basically backpackers mattresses), they work great for a day, or maybe two, then the printer sinks in too much and becomes noisy again.
Re: Proof of Harmonic Vibration/Resonant Frequency problem
I've been using a piece of gym floor mat that I had around. There are dozens of brands, all likely to work well. I have no idea what brand mine are. Should be available anywhere that sells gym equipment. Works great under the printer. No wobble, huge sound reduction.
Here's a link to something similar. https://www.amazon.com/We-Sell-Mats-Interlocking-Borders/dp/B01672KPQI/ref=sr_1_7?ie=UTF8&qid=1501190298&sr=8-7&keywords=gym+floor+mat