Are you really concerned about resolution, or machine accuracy? I'm highly skeptical of an MDF machine claiming 10 micron accuracy -- many high-end vertical machining centers claim about this accuracy, and these are with ground ways and ballscrew drives. However, they may have 10 micron resolution by virtue of their drive reduction -- this isn't that hard to achieve. A 10 microstep drive automatically gives you 2000 steps per revolution with typical stepper motors, and if your gearing is sufficiently low, say like a single start 1/2-10 ACME screw, you'd end up with a resolution of 0.0005" or 1.3 microns! Will you see that sort of accuracy? Not a chance.
Resolution is typically only a small part of machine accuracy, and just sets the increments for movement. Errors in the drive system (I believe the blacktoe is a chain drive), bearings, straightness of the components used, and other factors all come into play in terms of determining how close you get to your actual commanded position. What's your application? If you need local accuracy of around 50 microns (within a 50mm window, say), a lot of systems can provide this fairly easily. If you need 50 microns over a large distance, a lot of machines will struggle, as squaring and other errors tend to compound over larger distances.
Best regards,
Ahren
CNCRouterParts