Help with 3 axis CNC motor and drives

[domagoj55]

What do you think about replacing my first choice (Nema34) with this components:

3 x Stepper motors Nema 23

voltage 3.78 V
current 4.2 A/phase
resistance 0,9 Ohm/phase
inductance 3.8 mH/phase
holding torque 3 Nm
rotor inertia 810 g-cm2
detent torque 1.2 kg-cm

3 x Stepper motor driver M542H
voltage 20 – 100 VDC
current 1 – 4.5 A

3 x Regulated power supply 48V 5A

[JAZZCNC]

What do you think about replacing my first choice (Nema34) with this components:

3 x Stepper motors Nema 23

voltage 3.78 V
current 4.2 A/phase
resistance 0,9 Ohm/phase
inductance 3.8 mH/phase
holding torque 3 Nm
rotor inertia 810 g-cm2
detent torque 1.2 kg-cm

3 x Stepper motor driver M542H
voltage 20 – 100 VDC
current 1 – 4.5 A

3 x Regulated power supply 48V 5A

I would definitely use Nema 23 3Nm motors, thou those are slightly high on the Inductance at 3.8Mh I would look for some closer to 3mh or less.

For best performance run them between 60-70Vdc. Voltage greatly affects the speed/torque you can achieve from steppers so is important to get size right.

If you want really good drives then look at digital drives like the Am882 found here. Leadshine AM882 Digital Stepper Drive 80VDC 0.1A - 8.2A With Protection Function | eBay

But which ever you choose they will need to handle more volts than you actually provide to the drives.? So say if you run them with 65Vdc PSU then use drives capable of handling 75Vdc. Don't run them with voltage near the drives Max capabilty.

Regards the PSU then you don't need 1 PSU for each drive and can use just one PSU so long has it provides the Voltage and current(amps) needed.
Also if your using 3 motors rated at 4A you don't need 12A PSU and can use 8-9A supply.? This is because you'll rarely if ever be using all motors pulling full amps at the same time.

Often for larger supply's it's cheaper to build a toroidal PSU giving the exact power requirements needed. Unregulated Toroidal supply's are also better suited and preferred for the drives has they handle Back EMF better which stepper motors produce. They also provide consistent smooth power which drives like.

[domagoj55]

Jazz thanks,
i read a lot of posts on this forum. I saw that people really usually use only nema23 for hobby devices. So at the end i finished with three options. One that i already mention with nema23 motors (psu changed to 60v 600w). Price for that is around 450 $. Better nema23 kit is with nema23 motors with 2.5 mH inductance. That kit costs me around 500 $. The problem is that 500 $ is lot of money. I found also kit with nema23 3,8 mH and power supply 36V. I know what you and all guys said already, but difference between 250 $ for that kit and 500 $ for the best kit is huge. Is also difference in real world so huge? I did calculations with the cheapest kit, and with the most expensive kit. Both kit are fine with calculations. What should i buy? :(