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Greasing the bearings  

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Lvet
 Lvet
(@lvet)
Estimable Member
Greasing the bearings

Hello,

In another forum thread, I just read that despite what Prusa is saying, we should grease the bearing of the printer before the assembly.

My Mk3S is about 18 months old and recently, I noticed that the printer is making much more noise than usual especially when the z axis is moving.

Do you think I should worry? Maybe replace all the ball bearings?

Posted : 16/11/2020 6:12 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Greasing the bearings
Posted by: @luca-vicini

Hello,

In another forum thread, I just read that despite what Prusa is saying, we should grease the bearing of the printer before the assembly.

My Mk3S is about 18 months old and recently, I noticed that the printer is making much more noise than usual especially when the z axis is moving.

Do you think I should worry? Maybe replace all the ball bearings?

The bearings are normally only provided with corrosion protection by the manufacturer. This means that they should be cleaned and greased.
As with any linear bearing, where steel moves on steel, lubrication is necessary, otherwise the bearings either destroy the guide shafts or the ball bearings themselves wear heavily and become noisy or can jam.
This applies to all linear bearings on all axes.
Before you change the bearings, I would like to try some grease or oil to test if they run smoother. If nothing changes and the bearings run loud and rough, I would change them if necessary.
Here some information and hints from the manufacturer (Misumi):

Misumi_Linearbearings

 
Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 16/11/2020 8:15 pm
Lvet
 Lvet
(@lvet)
Estimable Member
Topic starter answered:
RE: Greasing the bearings

@karl-herbert

Thanks for your answer. Which type of lubricant would you recommend?

Would Dry PTFE lubricant in spray work?

I will try to spread it over the rods and (as far as possible) within the bearings.

Posted : 17/11/2020 7:36 am
--
 --
(@)
Illustrious Member
RE: Greasing the bearings

@luca-vicini

No - you must use a grease - something that actually lubricates the ball bearings. Dry lubricants don't do that well. And the grease must be INSIDE the bearing housing within the grease seals. Grease on the outside doesn't work that well. A light oil will be better on the outside of dry bearings, but the bearings will still wear a lot faster than if they were greased properly.

White Lithium Grease is the most recommended. Grade 2, though some applications can withstand a lighter oil base, like Grade 1. 

This post was modified 1 year ago by --
Posted : 17/11/2020 8:03 am
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Greasing the bearings

@luca-vicini

I would use a lithium soap grease or similar of penetration class NLGI 1 or 2. I personally use oils and greases from Liqui Moly.
e.g. NLGI 2 -> LIQUI MOLY K2K-20 or others:

Petronas NLGI1-2

Castrol NLGI1-2

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 17/11/2020 9:30 am
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