Ballscrew & Linear Rail Kit - Any Good

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Thanks for the advice on the bearings!

I was not sure if they even came with bearings?

I will take an image if there is any kind of stamp on them.

Presume I just take internal and external measurements and order the replacements

They always come with bearings, one double bearing in the BK and one single in the BF part.

Once you remove the four screws holding the dust cover of the BK12 you will see two bearings. I think the BF12 has a similar (but only one) bearing, but that is the floating end, so it isn't really critical. They are simple 6001Z 28x12x8 bearings.





These are cheap, but never the less can be very good. 6001Z is one of the most common type, so they are cheap, even if you'd replace them with an SKF or similar. https://www.skf.com/sg/products/roll...oductid-6001-Z

Of course, if you replace them, you might as well replace them with the best ...or not. Replacing 8 BK bearings if you have four screws can cost between 250 - 400 USD (maybe even more), so you must take it as a fairly large cost for an improvement of a hobby machine. There is no need for rushing, it's easy to do even later on, once you have everything up and running.

Never the less, I would not recommend you to start with replacing them, since there is really no reason, unless you really feel some serious issue, or play. I know I can't feel any, so even if some people laugh at them, let them laugh. Replacing is easy, but you need a proper tool, because these are really tight sitting in their seats. Don't use a hammer to get them out because that might damage the seating. There are tools to remove bearings, get one if you not already have one. Anyway, I don't think you will need to replace them unless you really feel there is something wrong with them. When it comes to wear and tear, I don't think you'll ever wear out these cheap bearings. It's a difference if you'd build a professional placing machine with high speed servos running H24/7, but as a hobby machine with slow rotating ball screws you will never come near the performance limit. In fact, inlines and roller skate bearings get a lot more beating than these, after all, these always rotate on smooth surface and at comparably very low speed.