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Bearing problem

calogerom

Bearing problem
December 12, 2014 12:53PM

Registered: 9 years ago
Posts: 83

Hi everyone! I have a question: is it normal that smooth rod (8 mm of diameter) moves inside bearing (LM8UU)? I try to measure diameter of smooth rod and it is 0,20 mm smallest than it should be. Can this be the problem?

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FatFreddie

Re: Bearing problem
December 16, 2014 07:37AM

Registered: 9 years ago
Posts: 34

I measured a couple I've got here and I get 8.00 for the good stuff and 7.97 for the less good, used ones. 0.20 mm is quite a lot and I would expect you to be able to feel it (the 8.00 rods do not feel at all tight in the bearings).

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cdru

Re: Bearing problem
December 16, 2014 08:13AM

Registered: 10 years ago
Posts: 869

Good smooth rod should have a tolerance around 10 microns (.01mm). You have 200 microns of tolerance which for a ground smooth rod for use with a linear bearing, is pretty bad. Was it advertised as precision ground rod? Or just as "tool rod"?

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calogerom

Re: Bearing problem
December 16, 2014 09:53AM

Registered: 9 years ago
Posts: 83

I bought an economic smooth rod. I should buy a new more accurate smooth rod

Edited 1 time(s). Last edit at 12/16/2014 09:55AM by calogerom.

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calogerom

Re: Bearing problem
December 16, 2014 02:05PM

Registered: 9 years ago
Posts: 83

In addition, in your opinion can i change my linear bearing (LM8UU) with new best linear bearing?

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cdru

Re: Bearing problem
December 17, 2014 03:52PM

Registered: 10 years ago
Posts: 869

You're bearings probably are fine. There are cheap bearings and expensive bearings, but I bet your "economic" rod will contribute more to the issue than what an "economic" linear bearing would.