608zz stickiness

I'm adapting the Z axis on my Folger 2020 to use 8mm lead screws. The design I have calls for 608zz bearings around the lead screws under the motor coupler. The bearing I have feel quite sticky. I have no experience with 608zz bearings, so I don't know if this is normal or whether the ones I have are not suitable. They move smoothly (no seizing or sudden jumps) but not freely. I don't know how to express this well, but think of it a like the sensation of pressing a knife through a piece of cheese instead of a piece of butter. Can anyone with more experience advise me whether this is just what like 608 bearings are like, or whether I need to get better ones?

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See my blog at [moosteria.blogspot.com].

608ZZ are "Skateboard bearings".
They have different quality levels, for example Abec 5 is the "allround standard", Abec 7 offers far less tolerances, Abec 9 might be overkill for a printer.
If you have no Abec rating on yours they might be below Abec 5.
In any case new bearings are not that easy to turn as the grease is still fresh, it takes some time for them to move without friction and if they do you missed the right to clean and re-grease them.

Thanks for the info!

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See my blog at [moosteria.blogspot.com].