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Noise on x axis with new LM8UU 24mm bearings

Posted by Lon 
Lon
Noise on x axis with new LM8UU 24mm bearings
January 09, 2018 05:16AM
Hi guys, my Anet A8 is in service for just over a year now and lots of clicking sounds appeared a while ago. Did some troubleshooting just to find out the heatbed bearings is not good anymore, and replaced it with pla or abs (can't remember which one) printed bearings (printed a while ago as spares) as per thingiverse stl file. No clicking noise anymore on my Y axis and runs smoothly, and decided to replace the 3 X axis bearings as well. Printed 3 new pla bearings and fit it, now there is a strange noise when the extruder move to the right and only noisy in one direction. I'll be very greatfull if any of you can give some advise here please. Belt tensions looks fine, but i'm not sure.
Please check attached vid.

Thx in advance
Attachments:
open | download - noise- (2).mp4 (546.2 KB)
Re: Noise on x axis with new LM8UU 24mm bearings
January 10, 2018 12:27AM
Almost sounds like the belt is scratching along somehwere. Or the printed bearings are too loose a fit and start rattling.
Lon
Re: Noise on x axis with new LM8UU 24mm bearings
January 10, 2018 01:03AM
Quote
o_lampe
Almost sounds like the belt is scratching along somehwere. Or the printed bearings are too loose a fit and start rattling.

My print settings were not the same as last time with the heatbed bearings, did not save it. But i noticed when fitting the X axis i felt that is not as sliding fit as the other, but good.
I was busy with other things and did not check belt tension again, i'll check and if tension is not the problem i'll print a new set.
I'll give an update on this maybe by weekend.
Thx for your time and response.
Re: Noise on x axis with new LM8UU 24mm bearings
January 10, 2018 07:26AM
PLA is not suitable to make good bearings and furthermore to get good bearings (made from Igus filament for ex.) they must be adjusted for minimal play (reamer or heat gun).
Minimal play means that everything must be properly constrained, well aligned. If not, polymer bearings will be hard to move, may seize. Too much play, they may rattle. Lubricant will help hiding these.
To get a smooth movement with no play, no lube is in fact much more difficult than with linear ball bearings.

LM and similar bearings because of the steel balls, will force but still move while wearing out quickly, themselves or the smooth rod if made of SS.
It is why all these crappy machines use them, mounting them via flexible means (non press fit, tie wrap, flexible frame ....) hoping they will last for some time.
Often the nerve wrecking noise leads to the user being worn out before.

Sintered bronze bushings are also an alternative.


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Lon
Re: Noise on x axis with new LM8UU 24mm bearings
January 10, 2018 09:39AM
Quote
MKSA
PLA is not suitable to make good bearings and furthermore to get good bearings (made from Igus filament for ex.) they must be adjusted for minimal play (reamer or heat gun).
Minimal play means that everything must be properly constrained, well aligned. If not, polymer bearings will be hard to move, may seize. Too much play, they may rattle. Lubricant will help hiding these.
To get a smooth movement with no play, no lube is in fact much more difficult than with linear ball bearings.

LM and similar bearings because of the steel balls, will force but still move while wearing out quickly, themselves or the smooth rod if made of SS.
It is why all these crappy machines use them, mounting them via flexible means (non press fit, tie wrap, flexible frame ....) hoping they will last for some time.
Often the nerve wrecking noise leads to the user being worn out before.

Sintered bronze bushings are also an alternative.

Yes i guess PLA is not the best choice for bearings, but that's all i have at the moment. Those on the heatbed works fine with no noise or stiffness, i'll print a set of 3 once more and see if i can curb the noise which only appears on the one side.
I'll post my result as soon as my printer is up and running again, Thx for your input on this issue.
Re: Noise on x axis with new LM8UU 24mm bearings
January 10, 2018 11:28PM
I'd look for IGUS Drylin bearings. They are a direct replacement for LM8UU and cheap, too (~1$/pcs )
Lon
Re: Noise on x axis with new LM8UU 24mm bearings
January 10, 2018 11:37PM
Quote
o_lampe
I'd look for IGUS Drylin bearings. They are a direct replacement for LM8UU and cheap, too (~1$/pcs )

Thx i'll try and get hold of them as spares anyway just to be on the safe side.
Lon
Re: Noise on x axis with new LM8UU 24mm bearings
January 21, 2018 10:56AM
UPDATE: I decided to print these with PLA, 4 on heatbed and 3 on extr now it has no noise or play and slide like a dream. Much better than the stock bearings when they were new.
Thx guys for your input regarding this.

Greetz.
Lon
Re: Noise on x axis with new LM8UU 24mm bearings
February 28, 2018 04:06AM
I did not use the pause option since i've changed the LM8UU bearings, now my prints is all ok if i don't pause. Pause postion maybe?
But pausing gives me a 6mm layer shift now, i've tried a lot of options like check belts & pulleys but i can't figure out why it only happens when pausing but not with normal printing.
Please advise what else i can try, cannot change filament now on my Anet A8. See att pic.
Thx.
Attachments:
open | download - pause.jpg (41.2 KB)
Re: Noise on x axis with new LM8UU 24mm bearings
February 28, 2018 09:13AM
Reread what I wrote.


"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Lon
Re: Noise on x axis with new LM8UU 24mm bearings
February 28, 2018 09:46AM
Quote
MKSA
Reread what I wrote.

Hi MKSA, i'm aware of your previous post regarding "home made" PLA bearings but why do i have decent quality with normal printing. This layershift only happens when print resumes after pause, and the next 3 pauses on the same print is no shift at all and stay on track.
Thx MKSA, i really appreciate your response.
Re: Noise on x axis with new LM8UU 24mm bearings
February 28, 2018 12:41PM
Most probably when you restart, these bearings exhibit such friction that the motor skips steps. Even good quality polymer bearings are less tolerant to poor alignment than ball bearings. PLA must be even worse as the heat will make it stick even more increasing dramatically the initial friction.

Edited 1 time(s). Last edit at 02/28/2018 12:42PM by MKSA.

"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)
Lon
Re: Noise on x axis with new LM8UU 24mm bearings
February 28, 2018 12:49PM
I'll take your advice on this and start saving for new bearings, printing is still possible without pausing.
Thx MKSA
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