Controlling 6 stepper motors and 2 spindles on a budget

[Freddo2016]

Hey guys!!

I am wandering of the best way of controlling 6 stepper motors as our project involves creating a double sided cnc machine. We have 2 stepper motors per axis and then have to control 2 spindles from top and bottom. The best kind of micro controller basically. We have looked into arduino on its own and then arduino cnc shields as well as raspberry pi cnc hat boards but we are unsure due to a lack of experience.

We were thinking of using an arduino uno with I/C expanders as we are on a budget, software like mach3 might be a bit too expensive for us. Would really appreciate any kind of help on this matter. Also, as we are new to this whole cnc industry, anyone have nay idea on how to approach the g code for this kind of system. The x, y stepper motors will all move at the same speed and then the z stepper motor will move at a different speed.

Also, any help on specific components and building we should be thinking of when creating this cnc machine in general would also be useful. I know this project seems very ambitious, it is more of a proof of concept rather than it has to work as I know most of you would be aware that would be a tremondous achievement.

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[Jim Dawson]

An interesting project and a bit of a challenge given the budget constraints.

Is this machine going to be used for a single repetitive operation rather than a general use machine? The free demo version of Mach3 allows you to run 200 lines of G-code, so for a repetitive operation 200 lines might be enough because you can put the program in a loop and run the same subroutine over and over. I have done this for special machines.

It's pretty hard to suggest specific components without knowing more about the machine, more information would be very helpful. The only thing that comes to mind at the moment is to make sure the steppers are large enough to reliably move the load at the required speeds.

[Freddo2016]

An interesting project and a bit of a challenge given the budget constraints.

Is this machine going to be used for a single repetitive operation rather than a general use machine? The free demo version of Mach3 allows you to run 200 lines of G-code, so for a repetitive operation 200 lines might be enough because you can put the program in a loop and run the same subroutine over and over. I have done this for special machines.

It's pretty hard to suggest specific components without knowing more about the machine, more information would be very helpful. The only thing that comes to mind at the moment is to make sure the steppers are large enough to reliably move the load at the required speeds.

Yes, I 100% agree it is a huge challenge most in the industry haven't heard much about multi functional, multi spindle machines.
It is a multifunctional machine that has to be capable of two processes. One welding and another deformation process. As a result of the welding, the structure/frame must be very stiff indeed. The main current issue that we are having is using an arduino to control 6 stepper motor in x,y and z. 2 on each axis top and bottom. We would like synchronisation on each of the motors. the x,y motors going at one speed and then the z motors going at another speed. We want the tools to move in unison so spindles both must move at the same time. 25KN axial force and 10KN radial force on the structure with 1000 rpm/30NM max torque for the spindle. The two processes are FSW and ISF (double sided).

Ok, we might have a try look into the free mach3 version.

We have chosen nema 34 steppers with a nema 23 planetary geared motor due to high torques due to the machining. I know the basics and I just wanted to know the best way of approaching it in terms of the mirco controller and building the circuit.

[Jim Dawson]

OK, I now have a better understanding of what you are doing.

If the X and Y motors run at the same speed and if they arrive at the stop point at the same time, then you could just connect the X and Y step and direction inputs together. That way they would be hard ''geared'' together. I don't know if that would be practical in this application. The speed is a function of steps/second, so if you want to move the Z axis at the same time, you will have to scale the Z steps as a function of the X/Y steps. Without further information, I assume that the spindle motor is controlled independently.

What you really need here is a motion controller, but any commercial motion controller would be way out of budget. Mach3 is a software motion controller and does a pretty good job for what it is. Not my favorite platform, but it works OK for lower performance systems. I have never worked with an Arduino so I'm not able to offer anything but general advice on motion control.