20 minutes into the first print and there is a squealing coming from somewhere. It is hard to pinpoint it. I put machine oil on the idler pulleys and that had no effect. It sounds like the belt is squeaking as if it is rubbing up against something. I looked but it isn’t obvious where it could be coming from.
Any ideas where to look?
I tried but can not find a way to upload a video so you guys can hear it.
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I did have squeaking of the X/Y belts on my X1C. Put a timy bit of lube on the edges to solve.
But perhaps try to first better pinopoint the source. There are a few othe candidates like the rails (recommended maintenance takes care of that) or the PTFE rubbing on the glass top.
This occurs when the top /or bottom edge of the XY Belts rub along the pulleys. If you’re lubing the “Pulley” and the sound goes away you actually lubed the belt ever so slightly.
You’ll notice an accumulation of belt dust building up on the rear tensioners underneath the belts. This phenomenon hasn’t been addressed directly from Bambu Labs as of now. But definitely proven within the BL community that if the belts are positioned within the center of the pulleys the sounds and coreXY system function as intended without issue.
Due to BL’s design of their CoreXY and the over 8 pulleys all in tandem, it’s near impossible to have the XY belt ride center on all of them. I’ve found retensioning the belts to actually travel center within atleast the rear pulleys to eliminate the rub sound but you’ll possibly encounter other small defects with Z banding or artifacts within small simple geometry models.
Each pulley would need to be within a very small variation of trueness to the bed versus X gantry. But when the belt applies tension to the pulleys it’ll shift forces against them unevenly as time goes on and simply from the motion of the system. If you’ll notice. many other high speed printers will utilize “toothed” pulleys for the simple reason of keeping the belt in a timed position with same tension along all of them. BL claims this was found to not be a adequate design for their printers and swapped to smooth pulleys before mass production.
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Hmmmm, it is new, but I will go through all the maintance stuff on all the rails and pulleys and see if that resolves the issue. My P1P has never made this noice and I have had it for almost a year.
thanks!
This sounds like the issue, is there a way to adjust these?
My original X1 ran smoothly throughout but had to be replaced. The replacement squeaked out of the box with the rod maintenance not removing the squeal. A spot of lube on the XY belts edges solved it though.
You’ll only be able to obviously adjust the tension on the rear XY Pulleys. So having multiple X1’s I’ve seen this issue start right out the box then “wear” in and vanish and be fine.
A 1 year old X1C and the issue persists if I were to follow the simple [Belt Tensioning] video provided by Bambu Labs. Mind you all functionality and quality in prints are still maintained.
The process of dialing the belt center on the rear pulleys is tedious for sure but doing so I did fully eliminate the squeak and rubbing of the belt. After measuring the distance of the tension springs the gaps seemed to only shift a few thousandths after operating the machine for a few weeks but this is expected as the machine cools down and warms up over and over.
[Here’s a nice video that represents the true method of a square belt tension calibration]
- I didn’t find the real need to use the tri-squares he did but focused on having the belts ride within the center of the rear pulleys when moved all the way to the front & then to the rear.
Best of luck!
ps: Definitely follow the BL guide line of not overtightening those 4 tensioner screws. I tested just how light you can tighten them while maintaining the hold on the springs and it’s the moment its snug you stop. no need to do an extra 1/4 turn or anything. just a barely snugh fit and they’ll hold
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Same here on the squealing. I have never added lubricant and still on the same belts. 2600hrs!
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My oldest X1C is currently @ 3923 Hours. BUT if you take a closer look, check the top & bottom sides of your XY belt for any remnants of fiber-fraying. If you see any [orange] that indicates the belt has worn down to the fiber-glass strands that make up the internal strength of the belts. This is how they hold form and resistance to “Stretching”.
My belt currently shows a series of areas that are exposed but I’ve trimmed the fibers that started showing. So some areas are orange and showing the internal sides of the belt while 70% is still black and solid as if there’s “High & Low” spots that rubbed away and don’t which proves the concept of the belt rubbing along the top or bottom of pulleys which translates to the “squeak” various users encounter.
I’ll never lubricate the top or bottom of the pulleys because that essentially avoids the [Graphite] washers job of maintaining frictionless motion of the pulley’s bearings. It’s merely a band aid fix for squeaking.
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Thanks for the info! I do have a spare set of all the belts.
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No problem, best of luck and happy printing!
THANKS! I used that video and adjusted my idler pulleys and got the belt to ride more in the center. it was running on the top of the pulley. Squeaks are gone!
Thanks @ProtoSpyre
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No worries! Glad to hear it! 
I do hope this gets a permanent solution with Bambu Labs next gen printers. It looks as if a simple channel guide would help eliminate the belt from shifting up or down the pulleys. At the very least it would ride along a metal guide that could be part of the frame which would keep the belt contained within a certain distance.
Happy to hear it helped you as it did me