hybrid steppers

[Muzzer]

About gearing down steppers - the torque falls off very rapidly with increasing speed, so gearing the motors down 2:1 probably doesn't actually improve the torque to speak of, yet you will half the maximum speed. Hmm, that's actually made things worse. If you plot the power against speed, you will see that steppers are generally close to constant power, so gearing them doesn't help a lot. It's different for servos which have lower torque but a much better constant torque range, so benefit from gearing down.

If you are looking for good resolution, go for a driver that can achieve proper microsteps (but not too many of them). Or possibly a motor / driver that has an encoder so that it does what you are asking. Oh, wait a minute....

With a 2.5mm leadscrew and 200 steps (no microsteps), you'd get about 12um per step. With only a few microsteps you will be well past what a machine of this build can achieve. You'll be doing extremely well to get under 5um surely?

[magicniner]

About gearing down steppers -

Acceleration and deceleration 'n' stuff ;-)

[komatias]

About gearing down steppers - the torque falls off very rapidly with increasing speed, so gearing the motors down 2:1 probably doesn't actually improve the torque to speak of, yet you will half the maximum speed. Hmm, that's actually made things worse. If you plot the power against speed, you will see that steppers are generally close to constant power, so gearing them doesn't help a lot. It's different for servos which have lower torque but a much better constant torque range, so benefit from gearing down.

If you are looking for good resolution, go for a driver that can achieve proper microsteps (but not too many of them). Or possibly a motor / driver that has an encoder so that it does what you are asking. Oh, wait a minute....

With a 2.5mm leadscrew and 200 steps (no microsteps), you'd get about 12um per step. With only a few microsteps you will be well past what a machine of this build can achieve. You'll be doing extremely well to get under 5um surely?

All very true. more speed less torque. The torque however is more important at the low speeds for acceleration and deacceleration purposes. When you are steady state, you should be ok if you do not want to be running at high rapid speeds.

2.5mm leadscrews would be a waste of time imo. A CNC conversion would need to be run on ballscrews and those are easy to find in 5mm pitch.

You can of course still gear it 1:1 through a belt to retain the handles. I know I used them shitloads on my kneemill conversion.

It all comes down to personal preference.

The voltage you run your motors on will largely depend on your drivers too. I think my original set of drivers from cnc4you disliked being run at 70V so had to get a 48V supply.