Linear Bearing Worn Out?

[Ritzy321]

I noticed I had been getting some weird finishes and a bit of play when pushing/pulling on my spindle ~0.1mm.

Disassembling the machine, the cars on the x and y axis had less preload compared to the z axis and would slide down the rail when held vertically.

So I decided to pull some cars apart and measure the balls..

measuring approx 20 balls
z axis car - balls were 3.974mm maybe a couple 3.973mm
x axis car - 3.967mm-3.972mm (mostly closer to 3.970mm)
y axis car - 3.959mm-3.970mm (average 3.965mm)

I have attached some photos on inside one of the y axis bearings, there seems to be some wear. looking at an x axis block only one of the bearing rows inside the block has some wear all the others are very shiny. The balls in both the x and y seem to be dull compared to the z axis.

The bearings were purchased from AliExpress which claim they are genuine but for the price...

Has anyone seen this before?

I'm guessing this is cause by misalignment maybe some dirt/chips in it? Should I throw them in the bin?

Unfortunately I've been burned pretty bad by everything I've bought from AliExpress (ball screws off centre, replacement ball screws bent, BK/BF bearings failing, faulty spindle etc..) I guess you pay for what you get.

Ritzy





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[Ritzy321]

Anyone?? What am I doing wrong???...

[mactec54]

Anyone?? What am I doing wrong???...

Bad linear rail alignment and surface mounting will wear everything out quite quickly

Linear Rails have to be precisely mounted and have very tight tolerances especially if they are preloaded