#Bad resonances after a few upgrades

35 messages · Page 1 of 1 (latest)

placid dirge
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I installed FMMM. dampers, and 48V, and my resonances after are worse or equivalent to before. I heard a bit of noise coming from the casing of the toolhead endstop, so I disassembled as much as I could. I can still hear some noise on Y, but the only thing left is the ball-bearings in the carriages.

I replaced the cable to the ADXL with an ethernet cable. I removed all panels, insulation, clips, webcam. I have rechecked all fasteners on the gantry. I have straightened the gantry and evened out the belt tension. The printer is on a floor on a semirigid rubber mat. Removing some parts has reduced input shaper recommendations in some cases.

I'd really appreciate any suggestions on this one.

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true dew
placid dirge
true dew
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interesting, those other peaks are perfect 2nd and 3rd harmonics, the base frequency being 55hz, 2nd harmonic 110hz, exactly twice the base frequency and third harmonic at 165hz at 3 times base frequency!

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so that isnt really "noise", its undampened harmonics from the super light, bare toolhead

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i suspect those will be dampened out by normally having the heavier components like the extruder and hotend, and are thus normally not too visible

placid dirge
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Okay, I'll load everything back up. It was not great before I unloaded it. Here's a video too.

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At about 20 seconds, you can hear the 50ish hz range with, what sounds to me like a ball bearing type sound that comes right from the toolhead. The other spikes sound like they come from elsewhere.

true dew
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the higher range kinda sounds like the belts rattling against the frame? could it be that?

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the 50hz range does sound a bit strange, very metallic as well

placid dirge
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It could be the belts against the frame, that does sound like where it is coming from.

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They're pretty tight, but they're not touching while stationary.

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Rather, the higher fq sounds like it comes from the belts, the 50hz sounds like the printhead.

true dew
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the belts might still need some more tension, you can really see the upper belt going in the video:

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placid dirge
true dew
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i follow this document and it has worked quite ever since

📎 belt.pdf
placid dirge
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I know that only does relative tension

true dew
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since i also had quite shakey belts, turned out I was way too loose

placid dirge
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Okay, I'll give that a read and report back. Thanks for your help with this.

true dew
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np! I run practically the same setup as you and have encountered this exact issue

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or at least, roughly the same

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its a Vcore 400 right?

placid dirge
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300

true dew
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ah okay, well most things should still apply with given upgrade setup, just higher frequencies

placid dirge
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Belts about 94hz from what i can tell with spectroid

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There's a peak around 50hz, but it's also at a spike in the noise floor

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Here's a picture with HVAC turned off

placid dirge
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@true dew Could you tell me if I'm interpreting this correctly?

true dew
# placid dirge

a bit hard to see, the lowest peak always lines up with the base frequency, which I would say is 50hz

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so in that case it would need to be tensioned into 86-100hz range as per the document

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the fact that the sound is so short also suggests that its loose, since it tends to sustain a bit longer