Hi-ho,
The only really high resolution stepper application I've seen first hand where the actual resoution was used was in a blood testing machine where a bunch of steppers directly drove a small pumps that pumped alternate samples and cleaning fluids in very accurate amounts though the innards of the machine.
The stepper motors used were very different from the ones we use in our machines, about 3 inches in diameter, and probably only an inch long. I assume that the large diameter vs length gave it more distance between poles, so the microstepping would be more effective, I'm guessing. I was servicing the printer attached to the machine, and got a look inside it while one of the lab techs was replacing something, he said they were 1024 microsteps.... (In a hospital pathology dept.)
You can still get high speed with microstepped steppers at silly resolution, but you need much faster step pulse sources than a PC can deliver. Mach3 does 45Khz, which if you're using say 256 microsteps, you'd only ever get a max speed of 52rpm, which isn't much good for much in CNC terms..
A reasonable speed of say 500rpm at 256 mircosteps, you'd need a pulse rate of 2.56Mhz... Which is just silly, but might probably not be unheard of in the world of expensive industrial steppers, although I've never seen one...
There are also some down sides to high resolution microstepping at high speeds, as it becomes less effective, and reduces torque. Hence some drivers 'transition' from micro to full stepping at some point around 5-10 revs/second.  |