Hi Joe and Kenneth,

Joe please dont think I was calling your work and 100% agree with Kenneth you have made a marvalous job and I'm sure it's been very enjoyable and great learning exercise.

I understand the single sided gantry does what you need but my mentioning this was to show that in the main it's not a good idea or design and the potential for problems and error is large. . . . Like you have probably found, has does just about everyone soon after building a CNC machine your ambitions to do more and cut other materials rise quite quickly and this design would very soon become a very limiting aspect.!! . . . You certainly couldn't cut aluminium or hard woods with it and be accurate.!

I don't have any issues with belt drive and it's very accurate but it would have been far better to have a single motor using a ratio driving a shaft connected to belts driving the gantry from both sides. It's a win - win higher torque better resolution.!!
Regards them being cheap then I've built a few machines using them and to be honest found by the time you have bought bearings, shaft etc (To do ratio setup), whether that be housing type or machiing your own housings and cheap bearings it just doesn't workout much cheaper than ballscrews from china and the work involved is much less with ballscrews and although belt is good it just doesn't match ballscrews.!

Regards brushless Spindles then my experiences are mainly of the chinese spindles and find these are very good and fully recommended them.! . . .Other than these then I can't comment really has I don't have any experience of any other brushless spindle.