Driving a CNC mill from Arduino/ramps

Hi I'm building a cnc milling machine and I want to control the machine using a spare set of electronics I have to keep costs low.

I have a spare Arduino Mega 2560, ramps 1.4 & 5 Polou stepper drivers.

I already connected a couple of the nema 23's to my ramps board of my printer and drives them both fine will be looking at motors' around the 2.3 amp range as I know these drivers will only drive 2 amp. I have heat sinks fitted will actively cool with a decent pc fan.

I have a 24v power supply 350w I would like to use to give the motors more grunt, I read about modifying the ramps board for 24v. What I wonder is do I even need the ramps board can I interface 4 steppers to the arduino, power them with 24v (Whilst Arduino is still 5v) and still use them with grbl?

Also could I use an Arduino Uno instead of the Mega as I also have 2 of them?

All I want is 24v for the motor's I think there must be an easier way than modifying the whole ramps board as I won't use the heaters.

Thanks

On the stepper drivers is two pins vmot and the gnd next to it.
If you remove those two pins form the ramps, you can plug 24v directly in there.

Some people put in the two pin pointing up, and then just plug in 24v. (just be sure there is no connection threw to the original ramps 12v pins)

Edited 1 time(s). Last edit at 04/27/2017 07:37AM by Dust.

Get a GRBL board

[www.synthetos.com]

[www.shapeoko.com]

Mount it atop Arduino UNO
hook up 24v power supply to motor drive

Go over to shapeoko forum
[www.shapeoko.com]

All kinds of info

have CNC fun

Thanks for the replies, I think I understand how to modify the ramps board. I looked at the grbl shield but I want to keep my budget low and I can buy a ballscrew with mounts for not a lot more than that and I would like to use 4 stepper drivers so I can drive the x axis with a driver for each motor to get the full 2 amps to all motors. If I understand the GRBL shield it has only 3 drivers so although I get a little bit more umpf for 2 of the motors I can a lot less for the 2 sharing an axis. Is this correct?

Doesn't this give the same functionality as a GRBL shield but for your own steppers?

[www.ebay.co.uk]

I'm guessing with this just plug in the stepper drivers, give it 24v and plug the motors in and the UNO and it's good to go.

Can I use all 4 stepper sockets on this though? Or is there another way to run 2 stepper drivers from 1 socket? What would happen if I connect all the pins from 1 of the stepper drivers (Except Vmot and ground) to another stepper driver so I have 2 steppers connected to 1 socket but power the 2nd one directly from the power supply to Vmot and gnd?

Thanks

Edited 1 time(s). Last edit at 04/28/2017 04:47AM by Desertboy.

There are GRBL boards out there with more drives (four)
and a lot cheaper than synthetos

[www.banggood.com]

GRBL is firmware to drive the CNC shield (g-code to motor drive)

CNC boards can use higher voltages 24-46 v

Your 24v supply will cost

Skimp on build? rebuild -- smoke --- rebuild

You could use a small DC-DC-boost converter to make 24V -60V from your 12V power supply. Way cheaper than a second PSU.

small DC-DC-boost converter to make 24V -60V from your 12V power supply?

A DC-DC converter to handle that voltage and sufficient current would be a true feat.

I think laws of Physics conserve energy (amps, volts) has to come from somewhere

Simple DC DC converter may be a nice heater --- trying to keep up with current load?

Got a link to your
small DC-DC-boost converter to make 24V -60V from 12V
that will handle current of 4 stepper motors on CNC mill.

I'm currently using a 600W DC-DC booster for 12€ to decrease bed heating time. They have an efficiency of ~80%. A 12V supply should have enough reserve to feed the extra amps.

I bought a cnc shield v3 for the arduino Uno (This is only temp solution to get working) once I feel better off I will change to T6600 drivers with a breakout board so I can use either linuxcnc or Mach 3 and increase the amps to the motors.

I'm going to drive this with 1 24v supply (have a 350w) and the arduino powered by the usb.

What firmware?
GRBL?

Is there other firmware?