I think whether to give one of the chinese eBay spindles a try or not depends on your motivation why not to risk a failer:
- if you don't want to risk losing money for a bad spindle it still makes sense to buy a cheap one from eBay: Even if the spindle or VFD is bad and even if the seller does not replace it you still save - usually a lot - money if you just buy a second one instead of buying a higher quality spindle from a US or European company.
- Same if you want to avoid downtimes -> just get a second one as spare and you still save a lot of money.
- Precision of the chinese spindles is usually good and the bearings should last long if used in DIY machines. But if used every day for demanding jobs they may not be the best choice.
- Another thing is electrical safety / insurance issues. If you buy from US / European companies you can be sure it meets all relevant regulations while the chinese spindle I bought needed to be modified to be "officially" safe (connectors with too low voltage rating). If used commercially or not familiar with electrical safety this is a problem.
Christian
My CAM Software and CNC Controller: www.estlcam.com