Hello . My problem is that I want to make a desktop cnc. And I have to get its parts. But I don't know how to calculate the current and voltage consumption of my 3 stepper motor. to buy a power supply for them.

 

Welcome to AAC!

What is the physical dimensions of your CNC machine that you are planning on building?
Have you selected the stepper motors?
The voltage rating of the motors will determine the voltage of the power supply unit (PSU).
Add up the current rating of all 3 stepper motors and multiply that by 2 to arrive at the PSU current rating required.
You will also require a PSU for the spindle motor.

I think it would be best to purchase all 3 stepper motors, drivers, controller, and PSU as one package.

 

Do you have the steppers selected or do you require to know the torque required for the machine?

 

Welcome to AAC!

What is the physical dimensions of your CNC machine that you are planning on building?
Have you selected the stepper motors?
The voltage rating of the motors will determine the voltage of the power supply unit (PSU).
Add up the current rating of all 3 stepper motors and multiply that by 2 to arrive at the PSU current rating required.
You will also require a PSU for the spindle motor.

I think it would be best to purchase all 3 stepper motors, drivers, controller, and PSU as one package.

Hello . Thanks for your guidance . No, I haven't chosen the stepper motors yet. And I still need help. This machine that I want to make has a size of 80 x 60 cm and I want to cut aluminum with it. And use the Arduino microcontroller. If possible, guide me more precisely about the details

 

Do you have the steppers selected or do you require to know the torque required for the machine?

I haven't chosen yet and I don't know what to choose. I want to cut aluminum, but my axis of movement is made with a lead screw and I don't know how to fix its vibrations.

 

My CNC is slightly bigger than yours. Mine is 100x60cm.
I used two synchronized stepper motors for X motion. Hence I used a 4-motor CNC kit.

You can follow the build here.

 

Keep in mind that NEMA refers to the mounting dimensions, not torque value, which can vary quite a bit across a range of motors that have the same NEMA mounting frame.
You can also get a wealth of info off the CNCforum, which is largely DIY.

 

My CNC is slightly bigger than yours. Mine is 100x60cm.
I used two synchronized stepper motors for X motion. Hence I used a 4-motor CNC kit.

You can follow the build here.

Can you cut aluminum with it? . Why did you use 4 stepper motors instead of 3?

 

Can you cut aluminum with it? Why did you use 4 stepper motors instead of 3?

Size and power of the CNC.
If you have a large gantry you will need to drive it with two lead screws.
Yes, I can cut aluminum. If you want to cut aluminum you have to design it for that requirement. It will not happen by itself unless you design for it. The biggest issue is how the spindle motor is mounted. I have a few things I would do differently which I will post later.

I will post some more photos on the other thread one day when I find some time.

 

Size and power of the CNC.
If you have a large gantry you will need to drive it with two lead screws.
Yes, I can cut aluminum. If you want to cut aluminum you have to design it for that requirement. It will not happen by itself unless you design for it. The biggest issue is how the spindle motor is mounted. I have a few things I would do differently which I will post later.

I will post some more photos on the other thread one day when I find some time.

I'm waiting for you

 

Do you have the steppers selected or do you require to know the torque required for the machine?

In your opinion, for 3 to NEMA17

How much power supply should I buy?

 

I am running four NEMA 23 stepper motors on one 36V 10A switching PSU.

 

I am running four NEMA 23 stepper motors on one 36V 10A switching PSU.

But what is the torque rating of the servo's?

 

I am running four NEMA 23 stepper motors on one 36V 10A switching PSU.

Can you help me to calculate the voltage and amperage of the power supply for the NEMA17 stepper motor

 

NEMA17 stepper motor

Stepper Motors:
All NEMA 17:


Notice The torque/current and length increases for the same NEMA 17 mounting.

 

But what is the torque rating of the servo's?

The torque on my stepper motors is 2 N.m.

 

I used rails similar to these round rails:


Next time, I would choose square:


Round vs Square
https://www.stylecnc.com/user-manual/round-square-guide-rails-cnc-routers.html

 

The torque on my stepper motors is 2 N.m.

=17.7 in-lbs

 

I run a similar system on a 48v 10A SMPS, but it uses only 6A typically. The important thing, to avoid issues like losing steps, is to ensure peak current requirements are met. It's very hard to assess this as it's quite difficult to measure and to some extent depends on your controller's motion control algorithm - ie how rapid an acceleration is demanded and the inertial load on the motor(s) - and how many motors demand this simultaneously. A 40 - 60% overhead on nominal running current is generally suggested.

Calculating actual motor requirements is a bit of a black art and the usual answer is to look at what others have done and copy it. A trawl around some of the build posts on here, CNCZone, MyCNCUK, Youtube, etc. should give a typical direction, but for your sized machine with 'typical' performance will need 1.5Nm NEMA23 motors running at 1.2 - 1.5A per phase. NEMA17 is too small, best left for 3D printers which are slower and have no cutting force requirements. Assuming a moving gantry machine the most difficult motion to cater for is the X direction as the whole gantry moves against the cutting forces. As said before, 2 motors and lead-screws, or sometimes 1 motor driving 2 lead-screws, are required to meet the inertial and static loading requirements and limit the potential for 'racking' where the gantry twists due to asymmetric loading when cutting off-centre.

Surprisingly, the cutting force requirements for cutting aluminium are quite small, a 1.1kW spindle is actually overkill with a single or two flute cutter. The biggest loads to overcome are the inertial load of the gantry and that of the ball-screw when trying to accelerate, which account for 25% and 65% of the required 1.5Nm motor torque, the remaining 10% being other inertial losses and frictional losses in the ball-nut, bearings and slides giving an overall mechanical efficiency of around 90% - these are typical figures based on a 10kg gantry (which includes the Y & Z motion as well as the spindle) and a 700mm 1204 ball-screw. Even a 2Nm motor would be marginal on that for rapids, hence the need to use two of them.

 

I want to cut aluminum, but my axis of movement is made with a lead screw and I don't know how to fix its vibrations.

Can you expand on that a bit more. Lead-screws rather than ball-screws on a machine that size can be problematic. What size lead-screw do you have?