question about cnc shield need help

Hello everybody I have a question about cnc shield and drv8825 driver

Please help me understand this concept I want to build my own 1000mm × 1000mm 3 axis CNC machine

My question is that can i use 3 drv8825 driver with 2 nema 23 stepper motor with one servo and arduino uno or mega?

I see many article using CNC shield v3.x in conjunction with drv8825 is needed to work properly ??

Or using just drv8825 is good ? Sorry for bad english Thanks in advance

You can use the DRV8825 boards by themselves but having the CNC shield makes everything much simpler, and given that those shields are pretty cheap I can't see why you'd want to put yourself through the work of creating your own carrier board.

Rebaz: My question is that can i use 3 drv8825 driver with 2 nema 23 stepper motor with one servo and arduino uno or mega?

If you have only 2 stepper motors then you only need 2 stepper motor drivers.

I wonder if a DRV8825 can provide enough current for a Nema 23 stepper motor - post a link to the stepper motor datasheet.

What do you mean by "servo"? If you mean a hobby servo such as is used for controlling flying model airplanes then they come with their driver electronics inside them. If you mean an industrial servo then post a link to its datasheet.

...R

Chagrin: You can use the DRV8825 boards by themselves but having the CNC shield makes everything much simpler, and given that those shields are pretty cheap I can't see why you'd want to put yourself through the work of creating your own carrier board.

Thanks for your reply The reason why not using cnc shield i want to learn everything about how electric are working so I want create my own board and understanding the things . I dont like cnc prepared shields

Robin2: If you have only 2 stepper motors then you only need 2 stepper motor drivers.

I wonder if a DRV8825 can provide enough current for a Nema 23 stepper motor - post a link to the stepper motor datasheet.

What do you mean by "servo"? If you mean a hobby servo such as is used for controlling flying model airplanes then they come with their driver electronics inside them. If you mean an industrial servo then post a link to its datasheet.

...R

Can u tell me which one is best for my cnc 100cm×100cm Nema 17 or Nema 23

I know nema 23 is more 400 step/rev but its bigger If i use ema 17 is problem occurs in accuracy ?

Yes i mean hobby servo for controling the pen but there is another question in my mind is G codes can be used for servo or needs to change servo with stepper motor ?

Sorry for many questions Thanks

The link from your Nema23 is actually to a Nema17 motor. Perhaps you have posted the wrong link.

Those numbers (17 and 23) are the widths of the front faces of the motors - 1.7inches and 2.3inches. They tell you nothing about the performance of the motor as there are many variants in all the different sizes.

You need to estimate the torque required for your application in order to identify a suitable motor. There is a suggestion for a simple method to estimate torque in Stepper Motor Basics. I had previously assumed you were past that stage.

Whether (or not) a servo can be controlled with GCode depends entirely on the program that is interpreting the GCode. I have not used it myself but I think there is a version of the GRBL program that can control a servo.

…R
Simple Stepper Code

Thank you so much Mr Robin ..i understand many things I decided to use 3 stepper motor for (X , Y, Z) using one of the these stepper motor

Nema 17 .200 step/rev or Nema 17 .400 step/rev

Can u explain what is best and sutabile (200 or 400 steps/rev)for my project(100cm×100cm) in relation to the board used (drv8825)

for my project(100cm×100cm)

This information doesn't tell us anything about your project goal(s).

This is just the outer dimensions of your machine. What we need to give a proper advice is: 1. what do you want to do with your CNC machine (-> materials to cut) 2. what spindle/router with what weight do you have or want to use? (-> determines mainly the torque of the z-axis and some information about the torque for x and y) 3. what speed(s) should be achieved in your machine?

There are more specific questions, but these 3 give us an indication what your project is all about and so we could verify your stepper choice and with that we can judge if a DRV8825 is ok or not.

A 100cm x 100cm CNC is quite big and if you don't want to just use it as a foam cutter, I suspect, your steppers will be too small to carry and drive the related load(s).

Rebaz:
Can u explain what is best and sutabile (200 or 400 steps/rev)for my project(100cm×100cm) in relation to the board used (drv8825)

Without the information that @rpt007 has mentioned I cannot comment on the suitability.

However the 200 step motor has a coil current of 2.5 amps which is well beyond the capacity of the DRV8825. The 400 step motor has a coil current of 1.7 amps so that could be controlled with a DRV8825.

I note that both motors seem to have the same holding torque inspite of the huge difference in coil current. I can’t explain that. If it is possible to get the manufatcturers’ performance graphs it might become clear whether there is a useful difference between the motors.

…R

You right nema 17 is very small…Let me explain whats in my mind please recommend me how build it.

1-
I want to create a CNC that can change the spindle so that doing
A. Cut very thin stickers(i mean paper sticker)
B. Drawing by pen

2-
Really i dont know how much weight because i dont create anything yet, but i know how to calculate
torque required = Maximum force x radius

I think for every axis needs less than 1 kg(if wrong please tell me)

3-
The speed be fast as possible

I attached the photo that i want cnc like that specially first attachment

Sorry for poor english

$_1 (3).JPG

Rebaz: I want to create a CNC that can change the spindle so that doing A. Cut very thin stickers(i mean paper sticker) B. Drawing by pen

I know this is Off Topic, but get yourself a Silhouette Portrait. I did. It's great. In case you are in the USA it is a US company but it is too tedious to get a link to the product on the US website :)

Back on topic, the loads for driving a knife for cutting paper will be low. I have these stepper motors controlling a small Lathe and I was able to use it to cut thin card (200gsm) using one of the Silhouette cutters. I bought those motors before I knew a lot about steppers (and they were cheap) and if I was choosing now I would probably get somewhat more powerful motors with a low coil resistance for a faster step rate. But I don't use the lathe much so I will probably not bother to upgrade them.

...R

Thanks so much for your reply I am in kurdistan and really i hate these Silhouette Portrait. I like to create by my self so later can modify and change to bigger.

I am decided to buying a 3 nema 23 stepper motor https://www.sparkfun.com/products/13656

with 3 drv8825 , so the last question can u think i am choosing wrong ?? If i use stepper with more torque can be a problem for my cnc ?

And which board is best ?

I don't think a DRV8825 is suitable for a continuous 2 amp output. And there seems little point in buying a large motor without also getting a suitable driver - for example one that can provide 3 or 4 amps and will not be in any danger of overload or overheating.

Even if you don't like the Silhouette products at least have a look at their size. There is certainly not enough room inside my Portrait for two Nema23 motors. I have not looked inside mine but I suspect Nema14 to be more likely.

Having more torque will only be a problem if it runs up against an end-stop and breaks something. In normal use it won't matter.

...R PS. I am using my Portrait with Linux and don't use the Silhouette software.

PPS. It might be an idea to write the code for your cutter to be compatible with the Silhouette so you can drive it with existing PC software. I use an extension for Inkscape.

...R

Thanks ..what you suggest for 3A output driver ?

This stepper is nema 17 right ?

|500x281

If this is nema 17 i can doing the same thing Sorry for too many questions

Rebaz: If this is nema 17 i can doing the same thing Sorry for too many questions

There is nothing that I can see in that picture to confirm the size of the motors.

But even if you know what size they are, as I explained in Reply #5 that is not enough information. There are two ways to choose a motor. Estimate the required torque by making some measurements or doing some calculations based on masses, accelerations and estimates of friction. Or guess and be prepared to have to buy different motors.

Maybe buy one motor and do some tests with it.

I doubt if the mechanism in the picture needs a high-torque motor. But more torque should allow it to work at higher speed.

...R

"This is a 1m square eShapeoko using a TinyG V8 controller board (Edge 438.02), nema 23 steppers for X and Y, nema 17 for Z with an acme screw upgrade, dual Y motors, dual X rails, limit and home switches installed."

https://www.youtube.com/watch?v=HVRXTZdxo3E

I'd still encourage you to purchase a CNC shield (like the RAMPS boards). I just don't see a lot of value in building your own; it's a lot of tedious work for something that's not much more than a bunch of connectors, fuses, and capacitors.

Thanks for your information