Resonance, spreadCycle and stealthChop
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@matt3o not sure if you've seen it before, but @Nxt-1 went through a lot of noise reduction stuff on his big delta a few months ago and did a very good job of writing it up. He even tried reinforcing the printer with concrete struts! In the end I think the maim source of noise was the motors themselves, so he got best results by fitting a torsional damper onto the motor shaft itself. I'm toying with the idea of getting some for my printer now too.
There's three long threads on it, but the final one sums it up best:
https://forum.duet3d.com/topic/18281/battling-sources-of-vibration-and-noise/82 -
@engikeneer thanks for the heads up, I'll have a look at that post, I made all kind of tests and I'm 99% sure the problem is with the motor shaft itself (not even the motor body). So what you say makes a lot of sense to me
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So the StepperOnline 17HS19-2004S1, I'll admit I was skeptical. It doesn't sound any quieter in Stealth Chop mode, if anything its noisier. But in Spread Cycle, its significantly quieter and smoother than the Moons. So quiet that I think I could live with them in Spread Cycle mode in general and leave them on the printer. That's a big deal if you are on the Duet 2 and don't have access to Stealth Chop.
The other big difference is the low frequency rumble is greatly reduced.
I don't know why any of this is so?
The moons are 1.04 Ohm and 2.2mH
The Stepper Online motor is 1.4Ohm and 3.0mH -
@garethky I believe my problem is mostly the length of the belts. I have a 400x400 print area and belts are about 3m per side... but of course I could be wrong.
As you've probably seen in the video I posted the vibrations at 4000mm/m are really bad and I doubt new motors would solve the issue completely. But thanks for your report, they are rather inexpensive motors I might give them a try.
In the meantime I'm converting my corexy into a corexyuv. Shorter belts and motors don't play against each other. I think I'm gonna make the first XY test later today... wish me luck...
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@matt3o said in Resonance, spreadCycle and stealthChop:
,..........In the meantime I'm converting my printer in a corexy into a corexyuv. Shorter belts and motors don't play against each other. I think I'm gonna make the first XY test later today... wish me luck...
I'm a bit confused by that. Did you really mean CoreXYUV or something else? It's just that a CoreXYUV use two gantries, stacked one above the other. So the belt lengths are the same (but you have more of them).
On the resonance thing, does it impact on print quality or are you simply trying to reduce the noise? If it's the former, there is a very simple solution.
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@deckingman said in Resonance, spreadCycle and stealthChop:
I'm a bit confused by that. Did you really mean CoreXYUV or something else? It's just that a CoreXYUV use two gantries, stacked one above the other. So the belt lengths are the same (but you have more of them).
each gantry has it's own belts. So instead of 2x3m I have 4x1.2m and motors don't play against each other (I do not get resonance on diagonals).
@deckingman said in Resonance, spreadCycle and stealthChop:
On the resonance thing, does it impact on print quality or are you simply trying to reduce the noise? If it's the former, there is a very simple solution.
no, I don't care about the noise, it's a performance/quality issue.
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@matt3o I'm also confused by what it is you are moving to. Can you post a diagram of the new belt layout? I assume your comment about not having resonance on diagonals refers to the "old" corexy setup?
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@gloomyandy said in Resonance, spreadCycle and stealthChop:
I assume your comment about not having resonance on diagonals refers to the "old" corexy setup?
yes, on a corexy I don't get resonance on diagonals. In what I'm building I have individual X and Y axis so only one motor moves to go in straight lines.
This is an old picture but should give you an idea. (yeah to be honest I don't know what is the name of this config. I believe I've seen it referenced as corexyuv once).
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@matt3o That ain't CoreXYUV. It looks like Cartesian with two X motors and two Y motors. If you try to run CoreXYYUV kinematics on that, bad things will happen.
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This, is CoreXYUV https://www.youtube.com/watch?v=mTPV3Ss1D-4&t=752
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@deckingman my bad
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@matt3o said in Resonance, spreadCycle and stealthChop:
@deckingman my bad
No worries.
BTW, the reason why you don't get resonance on a CoreXY when doing diagonals, might be speed related rather than simply the fact that just a single motor is employed. The way the belt paths are arranged on a CoreXY, means that when doing pure X or pure Y moves, the belts actually move something like 1.4X the carriage distance. So for any given carriage move at any given constant speed, the motor speed could be 1.4x different purely depending on the direction of travel. Easy to test - try doing 45 degree diagonal moves at 1.4x the speed that you get resonance on pure X or Y and see if the resonance returns. (EDIT - or it be 1.4X slower - can't remember which way round it is).
And finally, if you don't care about the noise but want to improve print quality (assuming that you really do have issues due to resonance), then simply add mass to the hot end. That probably goes against everything you've read because the 3D printing community has a fixation about reducing moving mass (despite the fact that mass is not a limiting factor of print speed). Any vibration due to the motors will be transmitted to the hot end via the belts. This vibration can set up a sympathetic resonance in the hot end if the mass is low (think tuning fork). By adding mass, you lower the resonant frequency of the hot end (think tuning fork with very thick prongs) so that it won't vibrate - or at least, it will vibrate at a much lower frequency.
It's easy to test - visit you local tyre fitting company and scrounge some stick on wheel balancing weights. Stick one on the hot end and be amazed
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@deckingman thanks for your suggestions. I just finished connecting the new machine and I'll check if this issue is present with this configuration as well.
Have you seen my video above? It's not really just resonance, the whole printer vibrates
I believe it mostly comes from the carriage on the gantry (basically on the head).The x1.4 diagonal speed test is something I should have done... and I really don't remember if I did... anyway I'm on the new config now... lots of rails, lots of motors, I hate it already but if it works...
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@matt3o said in Resonance, spreadCycle and stealthChop:
Have you seen my video above? .........................
Only the one you posted on 29th Jan - is there another? Difficult to to tell what's vibrating due to camera shake (or maybe an earthquake)
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@deckingman or maybe the printer shaking!
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@matt3o said in Resonance, spreadCycle and stealthChop:
@deckingman or maybe the printer shaking!
When the carriage is stationary?
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@deckingman it's that bad!
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@matt3o said in Resonance, spreadCycle and stealthChop:
@deckingman it's that bad!
Are we talking about the entire printer rocking slowly or something else? I thought your problem was high frequency resonance (as per title) rather than a very low frequency wobble. If it's the latter, surely you should be looking at fitting some levelling feet and maybe stiffening the frame, rather than messing around with motor settings.
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@deckingman I was kidding about the shaking. Sorry if it wasn't clear. It's a high frequency resonance that starts from the motor shaft and reaches the head carriage. No amount of weight on the head makes it any better.
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@matt3o That isn't obvious from the video.
But moving on ....... I note from your first post that you are using 0.9 degree motors. This might sound completely counter intuitive but have you tried 1.8 degree motors? If so, was it better/worse/the same?
Perhaps post you configuration files too - maybe one of us might spot something that could have a bearing on what you are experiencing (although I can't think what off hand).
In any case, let us know how the alternative kinematics works out.
