Official Luthiers Forum!

I have had a problem with the binding bearing set from LMI. It works great since I bought it, although some of the bearings were not running smooth. Fortunately, I didn't have to use them, so I didn't care. To avoid more problems, I kept my set in a box, protected from dust and rubbed with some oil to avoid rust.

But, today, I had to use one of the apparently bad bearings. I improvised an extractor to substitute it for a new one. What came next was surprising: the extracted bearing, supposedly bad, was running smooth, while the one inside the collar was hard. I switched them again only to find that whenever a good bearing was put inside the collar it ceased working. Clearly, the collar is too tight for those small bearings that get distorted easily. I passed the bearing a few times on a diamond stone and then it was smooth as it should. It still fits very tight inside the collar, but no more than necessary.

I have been searching the site trying to find more people that had the same problem, but I didn't see any. Am I the only one...?

Todd:

I know first hand that LMI stands behind all that they sell, and I strongly recommend this set to everybody.

I didn't send them back to LMI because it was easier for me to replace the bearing -- in part because I don't live in USA, and everything is more difficult from here. The bearings are cheap also, and I was sure that replacing them was going to be easy, as it was.

I think it is fair for Fernando to ask if anyone else has had similar problems. What is a forum like this for?

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It's not the miles ahead, it's the stone in your shoe


In Markham,Virginia

Thanks Jon, but I see that it is easy to misinterpret my post, no matter what I say -- may I ask the Administrator to remove it? Thanks!

The bore hole in the outer ring that the bearing goes into is a little tight or you and or LMI are not seating the bearings square to the hole. Either will squeeze the outer race causing the balls to bind. A little sanding in the bore will loosen it up. I would chill the bearing and heat the outer ring before pressing the bearing in, it should almost drop into place.

Fred

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

A bearing set like this is tightly tolerance machined to a specific fit. The journal to cup bore diameter tolerance is critical for proper bearing operation. Typically the cup to journal fit on this type of bearing is .0002” tight to .0001” loose. You should feel a slight resistance as you install the bearing on the journal. If the cup fits to loose, the bearing can end up running ever so slightly out of concentric with the journal causing the cup to miss-form in turn causing the bearing to seize. Also on an over tight fit the cup can be forced to expand also causing the bearing to seize. Micro fine dust partials and lead to this as well. A third thing is that the seals in this type of bearing system can and do go bad some times leading to fine dust entering the race also causing the bearing to seize. oxodarion/rust can also change the diamater of the journal.

I would first clean the journal and cup surfaces well with naphtha to remove the oil and dust and retry the fit. It always a bad idea to try to alter the journal (shaft) or cup (inside diameter of the bearing) as they are precision machined to a specific tolerance fit.