The video in the first post is pretty clear - resonance…
It does not always mean the initiator is the carbon rods, it can be the belts as well.
At just the right speed a tiny bit of free play somewhere will then be transferred onto other parts and areas of the machine.
Finding the source of the sound…
Check the sides and the back of the printer when it happens !
Check how those belts move! If they rub against the top or bottom of the tensioner too much adjust this.
Ok, no luck to locate it as it seems to come from everywhere ?
Use a garden hose…
NO, not like this!!!
Just the hose, one earplug and the hose on the other ear.
With the other end of the hose you can now ‘get a close look’ and eliminate noise from other areas.
Looks silly but works well.
You probably found some totally unrelated part making the noise, like some plastic cover or such…
Or you found that the entire housing starts to make the noise…
If you can fix the noisy part you need to find the source of the vibration that caused it.
Ideally using some model that creates those noises often.
Change the print speed slightly to see if the noise changes.
Not using the buttons, I mean actually reducing the speed setting by 30 or so mm/sec.
No luck, then try the same with the movement speeds.
One of these WILL change the noise or might even eliminate it.
How does this help ?
Well, once silent you can increase the speed in small increments until the noise becomes barely audible.
In most cases you will then find that the noise comes from a different area than in the previous test.
Usually around there is the real culprit.
Dry rods can be problem, a dry Y-axis creates binding and turns sticky - resulting in possible vibrations.
Belts rubbing, even if only on occasion, can transfer this as noise or in other words vibrations.
If it is not the rollers and tensioners check if there is something stuck somewhere - poop and strings land in all sorts of places you can’t imagine…
Those carbon rods can wear out, those sleeve bearings used in the head even faster.
The more play you get here the higher the chance things get transferred either from the head, belts, rods or transferred through them - like the nozzle dragging over the print…
Problem is that we can’t really feel the free play…
By the time we can we need new rods and sleeves…
It seems to happen when XY make a complete loop towards the front (closer to the door) when the bed is lowered towards the end of my print. Around 90mm lowered. Sounds like it’s coming from the back, but idk.
It doesn’t happen all in the first half of my print. I need a way to reproduce without wasting a lot of filament.
I have yet to take the back off. I’m just about to though.
The first time it happened it really didn’t seem to affect my print. But the latest one it caused some imperfections.
In the back you say…
Wouldn’t surprise me if you picked up some poop or filament strings.
I had a bad grinding noise every time my plate moved down but not up.
Couldn’t figure what’s causing it, only that the noise did not come from the rods or plate.
Found a piece of poop with a long piece of extruded filament attached it.
Was scraping on the backside of the rear wall of the chamber…
If it is happening towards the front but not when printing things in the back it could be you drive belts out of alignment.
Take the top off, turn the machine off and move the head around by hand.
Try straight moves for both axis first and observe how the belt moves in those ‘tensioners’ on the back.
A bit of going up and down on those rollers is fine.
But if you see the belt getting stuck on either end of the pulley when moving to the end or start of an axis you need to adjust them a bit.
Once you have the belts moving without rubbing on the flanges try to move the head more in a circular motion in different spots.
The belts will react differently as they now quickly change from being under tension to being ‘loose’ - the beauty of closed belt system over a straight one I guess…
If it was fine before you should not encounter any sever rubbing now.
But if a belt gets ‘stuck’ on a flange while you do the circles adjust the tensioner accordingly so you get a better run.
Why this hassle you wonder ?
Vibration and resonance!
A rubbing belt vibrates and those vibrations are transferred onto other parts of the machine.
Vibrations can’t be avoided.
Well, you can eliminated them as a manufacturer but then the price would be out of reach for most people.
The problem starts once a vibration causes resonance - it amplifies the noise.
And by noise I don’t mean the sound, I mean noise as in terms of vibrations of the unwanted kind.
Very bad if they make it all the way to the print head.
The print quality suffers but also those carbon rods as the sleeve bearing can start to ‘rattle’ - tilting back and forth within their free play rather than moving over the rod smoothly.
Even those metal Y-axis rods can cause severe vibration if allowed to run dry.
And trust me, if the lube is no good they run dry quickly, especially when printing high temp filament with a closed box.
Here the vibrations are caused by the balls in the bearings.
Without sufficient lubrication they can just slide over the rods instead of rolling.
And the missing grease film allows for undue free play.
I did some Arduino stuff back in the day, including using stepper motors.
If you ever hear just a belt running over pulleys compared to the sound once something is mounted to the belts and the system sits in a housing you know what I mean by vibration and resonance.
Bambu offers a nifty calibration for all this.
And some users abuse this feature once their machine starts to make new noises.
Don’t be tempted to do so…
It WILL cure quite a few noise issues that one might encounter…
But it will also mask any issues the machine might have as it then tries to compensate for them.
What works great in this calibration routine however does NOT cover all combination a real world print might come with.
Meaning while many prints come out just fine, you can suddenly get a not too complicated looking model failing all the time.
In case you already tried another full calibration:
Do those belts and make sure they stay as much centred on those pulleys as possible.
Clean the rods properly, then grease the Y and Z axis rods.
By greasing I mean to apply a FILM of grease but not smear it on there
If you have old microfibre cloth then cut a few strips and patches out of it.
Use those to get a nice film on the y rods - a ‘wet’ piece of cloth still takes off excess grease while making sure all missed parts still get lube - wet from lube, not water…
For the z-axis there some great slips as models.
You can clean out all old grease and also apply a fresh layer with them simply by letting the z axis move all the way up and down.
If none of that fixed the nasty noise you must have something stuck somewhere
I took the back off yesterday and everything checks out. The machine is only a few days old. One thing I noticed was the grease for the lead screws are at the bottom, but I don’t see much of anything above that.
I’m going to try doing all the maintenance stuff to see if things improve. I did notice that when printing a benchy things sound a little scratchy in the movement. Not the knocking noise I experienced, but not smoother either. When I look at the carbon rod, metal rods, and lead screw they don’t look dirty, but who knows.
I ordered the Super Lube grease and oil mentioned on the Wiki yesterday. I do have some grease packets the came with the machine, but no oil. The only oil I have is what came with my A1 mini. Is that the same stuff? (For the smooth metal Y/Z rods; I know not to oil/grease the X carbon rod and just clean with isopropyl; I have MGM 99.9% isopropyl, is that good?).
(I had an A1 mini for about a week until I decided to get an X1 w/ the sale going on).
