Hello from New Zealand

[3DPrintChCh]

I started 3D printing as a way to prototype products for myself and others in my little business, but now it has become the business!
So I gave it an easy name to remember and find. #3DPrintChCh

I got my Voron 2.4 kit and built it with great care, thinking this will half my previous print times.

On the whole, I'm very happy with it except for the slow speed rattling which is driving me crazy!

Id be building more of these but for the crazy resonance rattle.
Came on here looking for mods to help

[Simon2.4]

5 minutes ago, 3DPrintChCh said:

I started 3D printing as a way to prototype products for myself and others in my little business, but now it has become the business!
So I gave it an easy name to remember and find. #3DPrintChCh

I got my Voron 2.4 kit and built it with great care, thinking this will half my previous print times.

On the whole, I'm very happy with it except for the slow speed rattling which is driving me crazy!

Id be building more of these but for the crazy resonance rattle.
Came on here looking for mods to help

Hi and welcome to TeamFDM, Could you post a video of the printer working and producing the rattling, I'm curious. I built a fairly large modded printer where resonance control was primordial and got good results up to now though I'm still working on it. So anything structure related interests me.

[3DPrintChCh]

Hi Simon2.4,
I have been active in a discussion group specifically on this topic, and can add a video here as well.
I have been using some gcode that ramps through the speeds, 0mms to 100mms, and can hear two distinct resonances.  removing microstepping seems to have removed one of the resonances.
As far as I am aware, there are nothing else I can adjust to resolve this - belts are set at 120Hz, steppers are TMC2209 set to 0.8amp, etc etc.
Here is a link to the videos of the problem in a facebook discussion and the discord channel:
https://www.facebook.com/groups/voroncorexy/permalink/1290955957999634/

https://discord.com/channels/934415209404198972/934415209404198975

RegardsSimon with a 2.4 aka 3DPrintChCh

[Simon2.4]

3 minutes ago, 3DPrintChCh said:

RegardsSimon with a 2.4

So that's 2 Simon's with 2.4 !  You've been struggling with this rattle since November? Are your idlers actual 2GT , I remember a livestream by Nero3d where he mentioned some kits having idlers with square teeth rather than the curved profile of 2gt and this caused vibrations.

[3DPrintChCh]

That is very interesting info.  How can I tell the difference?
Here's a snap of my X carriage idlers:

[Simon2.4]

Wow it's hard to see such small detail. I just remember it being mentioned but gt2 is supposed to be a Sine pattern so no corners either on top of the teeth or in the bottom of the troughs. I see by your videos that you made spectral analysis, does any of the peaks match any components example: at 100mm/s of belt travel, a 2gt is likely to cause vibrations of 50Hz because 50 teeth will 'go by' in 1 second. In industry this is used to identify source of vibrations within complex machines.

[Simon2.4]

as for the resonance, I imagine you tighten all screws and checked mechanical 'health' since last November. Does it still rattle this hard?

[3DPrintChCh]

The loudest vibration on the spectral analysis seems to be a multiple of 50Hz: - 250Hz and 1000Hz
Where the bars are high in the image below.

 

[3DPrintChCh]

I'm happy to buy more idlers for a trial whether or not if thats a 'silver bullet' solution.  Just looking for the docs now for a recommended supplier.
Yes Simon it has less rattles since I deactivated microsteps - But since it is about 80mm/s its difficult to avoid it.  
As I mentioned in the discussion on Facebook, it sounds like a bang at the end of each swath as it transitions that speed at each end of a line.

[Simon2.4]

-have you determined at what carriage speed the vibration gets worse or is it 50Hz at all speeds. Is your enclosure complete: this helps mitigate effects of vibration though not the cause...

 

[Simon2.4]

im just throwing ideas out there but:

 cornering speed is set too low

acceleration too high

input shaper improperly adjusted

head is buzzing cause there is a screw somewhere that is too long and not pressing parts together

Screws become loose after first few hours of testing like on mine!

[Simon2.4]

11 minutes ago, 3DPrintChCh said:

multiple of 50H

That's typical harmonics, if you get rid of 250Hz (1st harmonic) others will probably go away. On your graph 250Hz is highest, so probably the 1st harmonic

https://en.wikipedia.org/wiki/Harmonic

[claudermilk]

Another thing that Nero suggests is to make a bearing stack in place of the toothed idler. I went ahead and did that in my build, though I cannot comment on its actual effectiveness yet--I'm still in preflight troubleshooting.

[3DPrintChCh]

Note: There is nothing loose/mechanical causing this - the cause seems to be a resonance interference.

I ran some further tests  - lt looks like the rattle occurs at movement speeds using both motors of F3200, i.e. 50mms

Im not sure how to do the calcs to know if this could be caused by the idler teeth - but I am keen to remove the teeth on those idlers - why do we need them at all?

[Simon2.4]

1 hour ago, 3DPrintChCh said:

why do we need them at all

you can test by replacing the idlers with a stack of bearings as suggested above, by @claudermilk

at 50mm/s going straight along X and Y, both belts will travel at 50mm/s so 25 teeth/s on both belts --> 25Hz oscillation could come from belt teeth. Idler has 20 teeth so It rotates at (25t/s / 20t) = 1.25 rotations /s --> 1.25Hz      motor shafts are 16teeth so (25t/s /16t) --> 1.5625 Hz 

And then any harmonics of those primaries may be observed. Example: If vibration comes from belts at 25 Hz, the 10th harmonic will be 250Hz  and if your frame likes to resonate at 250Hz this harmonic will appear 'louder' Vibration analysis is a profession... I had a course on this a while back and I remember 'some'

Edit: im refreshing my math, 250 is not the 10ht harmonic of 25 -->  actually it is

[3DPrintChCh]

Hi again - I received the 2x smooth idlers for the x gantry and tried them - problem remains at F3200

 

Edited March 1, 2022 by 3DPrintChCh

[Simon2.4]

You are going to have to meticulously look at all the parts involved I think. At this point, I would have taken everything apart and questioned all my assumptions. Are you sure that your belts are not over tight, have you tried with looser belts, just for the sake of analysis. If you are able to do so, measure the belt pitch to be sure its not stretched or poorly fabricated. bearing grease/tightness check, etc etc. I imagine you tried all that but I'm trying to give you ideas, I feel bad that you are having these issues. I wish I could help more.

[3DPrintChCh]

Thanks Simon - did you read the thread in the discord link  above :
https://discord.com/channels/934415209404198972/934415209404198975
- many things have been tried, especially by @Elcrni, so Im reluctant to repeat his investigations.
Thanks for your concern - yes it is sensible to assume there must be something wrong in the parts or the assembly causing it to set up this resonation - surely not the design - but the fact that quite a few people have this problem makes me wonder

[Simon2.4]

49 minutes ago, 3DPrintChCh said:

discord link  above

says I don't have access

[3DPrintChCh]

you probably need to join discord?

[Demosth]

58 minutes ago, 3DPrintChCh said:

you probably need to join discord?

The link does not work for me either The Channel must require permissions of some kind, or the link is incorrect.

[3DPrintChCh]

Link is correct for me. What is you Discord handle - I can try inviting you?

 

[3DPrintChCh]

Here is the official link to join the discussion on resonant vibration issue:  The people that set up the group related it to the MGN12 rails, so it has that weird name:
"https://discord.gg/jyDe5JqG"