What to buy when starting out

[JAZZCNC]

Hi Welcome.

Several problems with the chinese machines, electronics are mostly cheap rubbish and the wiring is poor quality. Depending on the which you buy the Spindles are also rubbish unless they come with the water cooled version.
Strength wise then they are Ok-ish but again they are low spec due to low price so Linear bearings are low quality so become baggy and loose over time, obviously depending on usage determines how quickly but it doesn't take long if pushed hard.
Also thou they use ballscrews most I've seen suffer from poor mounting of them and use either normal deep grove bearings for the Fixed end or very poor quality and fitting angular contact bearings.

I wouldn't recommend a second hand machine unless it's had easy life or/and is cheap and you can give it a good look over.
My honest opinion on these machines is they are Ok for learning CNC but if you want to cut accurately and with decent feeds and Depth's of cut and still have quality finish your better to spend the money on something better or building your own.

Hope this helps.!