Polishing Bearings

Table maintenance time. This week: when should bearings be cleaned, when should they be sanded, and when should they be mocked on the internet and discarded? The worst-of-the-worst photos are at the end of this post.

I’ve experimented a bit, and I’ve come to three conclusions.

1) Clean your bearings whenever they seem at all sticky. If a drop of lube doesn’t help, pull them out and wipe them clean. Clean bearings make a huge difference in play.

2) Check the feel of the interior when you remove the bearings. If the inside collar of the bearings feels smooth after cleaning, reinstall. If the inside isn’t smooth, but is evenly worn, polish them. If there are scratches or pits, they are hopeless and should be thrown away.

3) Do not over-tighten when you reinstall. Over-tightening will destroy the bearings. Use just fingers to tighten at first, and then a slight turn with a bearing wrench to get them snug against the wall so they don’t rattle. This is not the time to prove how strong you are. You can see from the photos below that the worst-of-the-worst bearings were all over-tightened.

Cleaning bearings is easy: pull them out of the table, get some cleaning solvent on a rag, and wipe out all the dust and dirt. Then drop them back in the table and add a drop of lube.

For sanding, the thing to remember is that the collar of the bearing should feel smooth to the touch. If you feel friction, it’s time to sand. Ryan Knapton’s video on NextLevelFoosball has some suggestions on how to refurbish bearings with fine-grit sandpaper:

I had over 100 old bearings, so I decided to record the process of polishing them. Most of them look great. I documented the very worst, though:

The bearing on the left is the worst I’ve seen. The collar of the bearing was completely worn away, and the entire length of the bearing had scratch marks. For comparison, the bearing on the right was in OK shape.

Here’s a side view of the bearings. On the right you can see that the plastic on the badly worn bearing was paper thin. It’s amazing this was still in one piece. I took a moment to appreciate the service this bearing had provided over the years, but it was definitely time to retire.

There is a deep curved scratch in the collar. My guess is someone tightened the bearing and turned the rod while there was a bit of sand between the bearing and the rod. Oops. Note the opposite end of the bearing is also worn: this bearing was too tight. Sanding didn’t help. I threw this one away.

This looks like a severe wear pattern from lateral rod motion. You can see at the bottom of the photo that the opposite end of the bearing was also worn. This is not normal. This bearing was too tight. Sanding didn’t help, and this bearing went in the trash.

Something created many small pits in the bearing collar. Not sure how this happened, since the wear pattern doesn’t make it look like the bearing was too tight. Sanding didn’t help, this bearing was retired from service.

This bearing was in OK shape. Here’s a photo after refurbishing. You can see the wear marks in the collar, but the collar surface is buttery smooth to the touch. This bearing will go back on a table!

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