A resonance study - test series
...was having an alternate conversation and a few points were brought, correcting my (misguided?) insight that was based on what i'd been seeing in my setup.
So off i went to run a bunch of tests. Using my scale pull test to set a calibration point on my meter I set my belt tensions to 1 lbs, 2 lbs, 5lbs, and 10 lbs. running belt tension tests ate each tension. 'THE' tuning video says you should have two peaks per belt tension. BUT... I'm now running into manufacture specs vs end user prescriptions that do not agree. At 1-2 lbs, I kind of get a sloppy graph with a second peak for each belt. but I can watch the belts vibrate badly and slap the frame and even the gantry on this VC500 at those low tensions. At 5lbs (which is still well below the manfuactures suggested tension) I get one sharp peak, and no secondary peak as the video suggests.
At 5+lbs, (apparently I was running at around 6.5 lbs) is my highest acceleration suggestions when running input shaper.
So my conundrum now is which do I follow. The mfr spec, or the wisdom of those that have gone before me, and the rest of the masses.
examples follow...left is two lbs, right is five lbs of tension
17 Replies
and 7 lbs
I guess I should have run resonance graphs at each poundage as well. Oh well...like they say...hindsight is always 20/20.
genetic-orange•12mo ago
How much deflection? 1”? Is that on both sides of the print head for both top and bottom belts?
??
genetic-orange•12mo ago
@ptegler - you had said 2 lbs and 5 lbs of tension, is that how many pounds it takes to pull it 1 inch/25mm away from the frame? Some other number? I have no idea how to read the charts but your last chart I think looks great to me... but really that is from watching one video that was posted here, so I have no idea.
original message...calibrating a gauge to measure belts https://discord.com/channels/582187371529764864/1070922740007194665/1070922740007194665
dependent-tan•11mo ago
what are the frequencies when checked with spectroid??
?? If I perceive the Q correctly... they match the gates spreadsheet numbers. That's actually what I was doing...mechanically validating the calc'ed numbers...sound test and direct measurement. They matched well enough for me to believe the spreadsheets
dependent-tan•11mo ago
if you open the spectiod app what HZ value does it show
thats what im trying to match
i dont have the other tools you used
i want to try and match a frequency to 7lbs of tension
I don't know what you're asking that I haven't already stated Are you refering to the pics of that test setup and what I set mine to?.
dependent-tan•11mo ago
ok let me try and ask it differently uummm
honestly...can't say I remember...pretty sure I have mine set to 6-7 lbs range. On the VC500 that put me around 62-68 hz. but different sized machines will be different 'frequencies' for the same tension. Just like a guitar...length can be the same but tune can be different...hence differnet string diams. instead of length changes
using the scale pull to measure your gauge, you can then easily set up a scale and test as needed.
dependent-tan•11mo ago
ok so i see that you used the manufacturer list tensions based on the tool you made and then tested that with lbs of pulling tension, im trying to combined the data you collect and match it to the data that everyone normally uses, i.e. hz frequencies, a sound measured by the app called Spectroid, you pluck the belt and it detects the resonance frequency of that pluck and shows the Hz value, and then ill know what Hz value matches 7lbs...
im also running a 500 this is why im so interested
and yes that answerewd my question thnak you
but the part that confuses me is that 68hz on mine is super loose....
you had me wondering...so just pulled everything out.... I'm at around 82 hz... belt gauge on my 'blue mark' blue mark on my scale says 6.5 lbs
so 68 as you mention is 'spec' but I find running a bit tighter works for me. then again I have ball bearings (to and bottom) on my drive pulleys, . metal xy joiners and carbon fiber plate front idlers so tension is not an issue (yet?)
So at higher tensions, the two peaks disappear? If I remember correctly, the two peaks are the two partial beltpaths as seen from the motor, one shorter and one longer. Because of their difference in lengths, they resonate at different freqs which is causing those two peaks.
But why would they disappear? Because those two belt segments behave as one at higher tensions?