Ok, so I broke down and bought a high speed spindle from Wolfgang for my soon-to-arrive Taig. Since he just released a heavy-duty Taig mount for his spindles, the combined purchase was too hard to resist.

I'll be using the spindle to finish mill 6061-T6 aluminum using 1/32" cutters. The spindle includes a 540 can motor (brushed and inefficient) running flatout at 20K RPM, but I'd like to use a brushless motor instead.

The spindle is rated at 100K RPM, but I'd like to target around 40K RPM.

The brushless hobby motors used in RC airplanes look perfect, but I'm not sure they can handle the continuous operation (up to 12 hours continuous). I would suspect that the bearings would be the part that would fail over time, and I'd like to run it at 20K RPM using a 2:1 belt between it and the spindle, giving me 40K RPM at the cutter. Load would be light, since the 1/32" cutter would be eating at only about 15 IPM max.

However, I don't want to waste my money buying something that might be unsuitable. Has anyone else used a brushless motor like this with their CNC mill? Are any "warning bells" going off in your heads as you read this?

Thanks,
---Will