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Y axis linear bearing rod noise  

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bob-5
(@bob-5)
New Member
Y axis linear bearing rod noise

I just noticed this, but my bed linear bearing rod nearest the controller is moving.  Every time the bed changes direction, the bearing rod slides 1/4” and makes a loud clicking sound. Once the rod hits the stop the Bearing moves and the bed keeps on as though nothing has happened.  If I hold the rod with my finger the noise / movement goes away.  I’ll try to tighten the end caps when current print is finished.

Anyone else have this problem? 

Thanks - Bob

Posted : 14/04/2020 6:28 am
keith.g5
(@keith-g5)
Eminent Member
RE: Y axis linear bearing rod noise

Hello Bob,  If  understand your issue correctly, it sounds to me that the rod you mention is too short.
So let's start there. As I measure my Mini, the length of the outside dimension Y axis frame is ~285mm (11 1/4") . The front and rear Y axis plates are 12mm (~15/32") thick. Minus the locating bore depth x 2 (20mm) that would make the max length of the Y axis rods to be ~265mm (~10 7/16") I would suggest that you remove the Y axis rods, measure and compare their length. If one is at least 6mm (~ 1/4") short I would contact customer service. They're quite helpful.

  

Posted : 16/04/2020 10:54 pm
bob-5
(@bob-5)
New Member
Topic starter answered:
RE: Y axis linear bearing rod noise

Thanks for the reply Keith.  I suppose I will take it apart and compare the rods.  It looks somewhat non-trivial (thanks to the belt),  and the rattle doesn't seem to impact print quality.  Probably a tiny spacer would stop the movement.  Maybe even some glue (then I wouldn't have to take it apart).  Hmmm.

--Bob

Posted : 16/04/2020 11:10 pm
keith.g5
(@keith-g5)
Eminent Member
RE: Y axis linear bearing rod noise

Sorry, mistake on length of rod.   The length of the Y axis is most likely 280mm.  As I incorrectly stated:  .

Minus the locating bore depth x 2 (20mm) that would make the max length of the Y axis rods to be ~265mm (~10 7/16") .

The length of the rod would most likely be 280mm.  I meant to say; total frame length minus remaining of thickness of both end plates, is 4mm. knowing the bore depth. So, 285mm minus 4mm is 281, so for ease of manufacture including tolerance, lets go with 280mm overall length of the Y axis rods.  Sorry for rambling.

Posted : 17/04/2020 2:53 am
bobc
 bobc
(@bobc)
Reputable Member
RE: Y axis linear bearing rod noise

According to a teardown thread[1], the measured length of the Y rods is 279mm, so that sounds the right ball park.

[1] https://forum.prusa3d.com/forum/hardware-firmware-and-software-help/worlds-first-teardown-bom-bill-of-materials-closest-look-for-prusa-mini/

Posted : 17/04/2020 11:32 am
bob-5
(@bob-5)
New Member
Topic starter answered:
RE: Y axis linear bearing rod noise

Okay, I took apart my y axis and both rods are 28cm as expected.  The holes in the plastic end caps are all 9.67mm deep, and the extrusions are identical in length as well.  This made me ask why only one side was sliding so I tried a little harder and sure enough both rods slide 3/16" of an inch or so.

I assume these are design tolerances.  It is just an annoying noise, so I stuffed one of these "furniture pads" in each hole and now the rods are unable to slide.

Problem solved -- Bob

Posted : 17/04/2020 9:58 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Y axis linear bearing rod noise

As long as the pads leave a little flex for thermal expansion and contraction that should be a fine solution, regards Joan

 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 17/04/2020 11:59 pm
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