Quote Originally Posted by A_Camera View Post
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.
It's not about laughing at people it's about trying to let people know the difference between building the right vs the wrong way. Everything about these is Wrong and pointless for a CNC machine.
They are deliberately made and sold this way to keep the price low to make the kits look cheap with NO regard to whether fit for purpose or not.!

Those bearings in the BK mount are completely wrong for the application as they are not designed for lateral loads, they should have Angular contact bearings, not deep groove bearings like 6001ZZ.
They will wear excessively and they will introduce backlash, even if fit with SKF bearings because they are not designed to operate with lateral loads. Also, to get preload on the bearings and reduce backlash puts extra load on the bearings causing friction which robs power from the motors, again causing extra unnecessary stress on other components like drives, PSU, and lowering performance.

I don't understand why anyone would buy components that are not fit for the purpose, then spend more money on them to put or right and even worse spend money on them replacing bearings with the same inappropriate bearings. Especially when buying correctly the first time isn't that much more expensive and far less hassle.