Hello Everyone. I purchased some linear rail and ball screw sets from linearmotionbearing2008 on

General CNC CNC Routers
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Hello Everyone. I purchased some linear rail and ball screw sets from linearmotionbearing2008 on eBay earlier this year. Some of the bearing blocks “stick” when I move them by hand. When I contacted them they said to trim the rubber seal. When I look closely at the block when it’s moving I can see the seal fold back under so it seems that this could be the cause.

I asked on another forum about this and was told that “sticky” bearings are actually a good thing as they help prevent backlash. There’s a set screw on the top of the block but that doesn’t seem to change the “stickiness” (great technical term). I’m an electronics guy and this is my first venture into CNC so I’m hoping to get some feedback on what I should expect and what I actually want.

Here’s link to quick video of me moving the bearing blocks along the rail,
https://www.dropbox.com/s/qr756n0mqyzmcq5/2013-06-02%2021.01.49.mp4

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I think you and the forum are talking about different types of stickiness.
Your seals cause the bearing to drag a little. You can trim the rubber if you want, but from watching the video it seems to me that you probably don’t need to worry about it at all. Mine always drag a little like that, but have never caused any issues even when I was using 40oz steppers.

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Thanks Jake. Wasn’t sure what to call it and wasn’t sure if it was something to be concerned about. It was just odd that about half acted like this and the other half glided freely down the rail.

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You’re welcome.
It’s probably just manufacturing differences in lots. The rubber seal is really just there to wipe the shaft clean to keep debris from entering the bearing. Yours will just be extra clean :slight_smile: