what is this extra peak....

belts arent binding anymore. got good belt resonance graph. but still have this blue peak on my Y resonance. while X looks pretty good.
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20 Replies
Fruitz
Fruitz•10mo ago
ive gone ahead and tightened evyerhting. not sure what else is loose. and only on Y. hmmmm
MFBS
MFBS•9mo ago
What model and size printer?
Fruitz
Fruitz•9mo ago
200 vcore 3.1 @MFBS it seems to be the z. got way smaller second peak by removing the bed during the test. is this the rear motor mount flex your gold series deals with ?
MFBS
MFBS•9mo ago
That peak is from Z movement.
Fruitz
Fruitz•9mo ago
yeah. seems to be the whole z kinematics moving
MFBS
MFBS•9mo ago
Something is causing an 'apparent' movement of the ADXL sensor vertically. How much rock do you have in your print head?
Fruitz
Fruitz•9mo ago
with the bed removed. the peak is significantly reduced. not a lot. and even so it would fall under the same frequency as the main peak no ?
MFBS
MFBS•9mo ago
No not necessarily the same frequencey and more likely not. The ADXL sensor is not just measuring resonances in your belts but any resonances that cause the ADXL sensor to move.
Fruitz
Fruitz•9mo ago
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Fruitz
Fruitz•9mo ago
heres two graphs. left is without the bed attached. right is with.
MFBS
MFBS•9mo ago
....and it thinks' it is moving vertically How stable is the table you have it on?
Fruitz
Fruitz•9mo ago
its on the floor lol no concrete. nothing. just the floor. the second peak vibrations are actually audible now that its on the floor.
MFBS
MFBS•9mo ago
Is it possible to determine where the noise is coming from?
Fruitz
Fruitz•9mo ago
ill do a resonance hold test tomorrow and see
MFBS
MFBS•9mo ago
Is your ADXL board mounted securely? I am sure you have already checked, but just double checking.
Fruitz
Fruitz•9mo ago
yeah. mounted to the eva im probably gonna reprint it all in PCCF soon enough. the petg is definitely not great for rigidity. it maybe a mix of a lot of different things. removing the bed definitely helped but the eva may just be too flexible a bit disappointing since its RatRig printed parts.....
Ferfi
Ferfi•8mo ago
A thing to note is that vertical value for the second peak is the same but the first peak gets smaller. But I am not an expert on what PSD is (vertical axis) I'd say that the graph is saying something different than what you're reading.
Fruitz
Fruitz•8mo ago
PSD is amplitude of power per frequency. The graph can be read as range of frequency on X and amplitude of frequency Y. But yeah. It seems like it's just the Eva toolhead wobble in the Z component now that I re look at the graphs. Secondary spike remains the same. ( This is very different than my previous tests as the secondary spike always seemed to scale with the main. )
Ferfi
Ferfi•8mo ago
IIRC the PSD is simply said something like "what percentage of a total sum of deviations occurs at this frequency" Not sure how to put it into writing The narrower the peak interval on X is, the higher the peak will be on Y
Fruitz
Fruitz•8mo ago
Well every frequency is made up of multiple different frequencies. PSD is the sum of all those frequencies. In 3 dimensions there's a good few frequency peaks across the range with an averaging peak as the "main" in 2 dimensions So in simple terms amplitude in 2 dimensions. It's measured here in decibels too. Yes that is true. To a point. There's still an involvement of Injecting enough energy to out scale any noise. Hmmm Funny thing is. If I attached the adxl via nozzle mount. I get a perfect singular spike on Y And its way higher frequency. But it seems like the machine doesn't like it overall as it's way way louder and motors sound angrier 😂
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