Starting to design out my build, looking for critique

[MartinS]

Yes, thanks, most helpful.

So in short yes they are different and need special drives, No they are still stepper motors.
Often you buy the closed loop drives and motors together as a set. Like these.
https://www.ebay.co.uk/itm/CNC-Hybri...IAAOSwjlVcIJIb

https://www.ebay.co.uk/itm/NEW-Leads...UAAOSwqFBbvGxS

I guess that we still need a low inductance. I can't see it specified in the links.

[JAZZCNC]

I guess that we still need a low inductance. I can't see it specified in the links.

Yes the same applies but I've yet to find a Closed-loop drive/motor combination that uses high inductance motors and just about every set I've used gives reasonable torque at higher speeds, most reach 1500rpm before torques drops away.

Also, there are closed-loop systems that use 3 phase motors which give much better torque and smooth operation. To be honest I mostly fit 3 phase systems on larger machines.

The only thing you have to watch for with smaller closed-loop systems is that they use low voltage, often 50Vdc drives and they do not tolerate more than 50V and will be damaged if rises above. This means you need to run safe margin, 44 - 45V is recommended. That said they still tend perform very well and better than a standard stepper at same voltage. Think this must be to do with the way the closed loop drives work.!

The bottom line that I've found is that closed-loop systems tend to be slightly stronger at higher feeds and the closed-loop drive ensure the position is maintained.

That said a correctly sized and set up Open-loop stepper system is just as accurate and shouldn't lose position if tuned correctly. Thou Closed-loop systems are coming down in price and the difference in price is now such that closed loop is the wiser choice.

[Chrono]

So, if i got that correctly, I want a stepper that has a low inductance rating and a high current rating, correct?

I plan to use a single NEMA 34 for both X-axis screws(2x 1800mm 2020 screws, around 75kg of mass on the gantry) and a single NEMA 34 for the Y axis as well (1300mm, single 1620 screw, around 25kg of mass to move), with a NEMA 23 for the Z-Axis(single 500mm 1610 screw, 15kg). Taking another look with those qualities in mind, I come up with the following choices:

• X-Axis: ST8918M6708-A
• Y-Axis: ACT 34SSM8460EC
  
• Z-Axis: 60BYG401-03
  

Would these be good choices for my system?