Quote Originally Posted by A_Camera View Post
...for that price...? I mean, seriously, if the bearings are crap you buy some SKF quality bearings and replace them. It's a 5 minute job. Mine are so far perfectly OK. I just bought another kit. This one:

https://www.ebay.com/itm/393113635297

Will get it by next week and I expect it to be as good as the previous ones, which I bought on Aliexpress and not from the same seller.
Not a fair comment really because Clive S makes a valid point.? Many of these kits will and do come with standard deep grove bearings which are completely unsuitable for CNC or at best they use cheap nasty angular contact bearings which need constant adjustment and wear out within months.
Many many people have bought them only to find this out after the machine is built when they are chasing chatter or error from backlash etc.

SKF Angular contact bearings will cost £20 to £30 per pair and for the same amount or not much more you can buy much higher quality C5 BK bearings from Fred at BST. These are light years different in quality and will last years. So sometimes it's false economy to buy too cheap.

I agree these kits are light years better than threaded rod etc and are a great way to get started building a CNC machine provided you don't expect top quality and accept they will wear out and become sloppy quickly if not maintained and cleaned on a very regular basis. They won't tolerate harsh conditions very well either.