Max combined stepper current for ramps 1.4

Hi All
First time here.
So just got a ramps 1.4 Mega 2560 combo up and running on a CNC router. Looking at upping the power to the steppers. Can get 1.8 amps per motor x 3 motors currently but thinking about doubling up the Y so total 4. that's 7.2 amps then have to run the rest of the board fans etc. The rated input is only 5 amps? Is the board ok running at this higher load or is it just going to blow something up. Is there a way of tapping some power from the 11amp supply? I'm not using any heated bed so that dormant.

Cheers

... 1.8 Amps would overheat your stepper drivers - you should reduce drastically and/or add superior cooling.

The drawn current is not continuous, so drivers set to 1,2 Amps x 4 won't be 4,8 Amps, but more something like 3 to 4 Amps averaged ... so 5 Amps rating should be enough ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Thanks. Maybe will try and measure real usage. I have the drivers set to 1.4amps at the moment. They get a little warm but seem ok. Have a fan blowing on the heatsinks. Keen to get a bit more power out if it. Would like to bump the voltage up also but not sure there is an easy way as the ramps seems limited to not much more than 12v reliably. Seems a few mods to the board and then still a little limited. The drivers can seem to take 45v.

Actually on the DRV8825 would it work if you disconnected the VMOT and GND (next to VMOT) and connected that to higher voltage say 24+v? The drivers say they can take upto 45v. Just need to give them a decent supply.

Cheers
Mark

Hi Mark,

... depends on your drivers - the GND should be connected, but the Vmot can be higher than the RAMPS supporting voltage - have running RADDS boards with 24V and own variants with 44V

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Right so should be able to pull the Vmot pin out of the driver, maybe reverse it so it sticks up instead of into the Ramps board then run higher voltage to it.

Cheers
Mark

... only problem is the possibility for "reverse shorting" the support voltages by driver faults - if you blow the driver, there is a chance, that Vmot will be connected with your 12V

To be safe with higher voltages, better use external drivers ...

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I would grab some of these THB6064 drivers they have a cable that plugs right in the RAMPs board and makes the project upgradable if you want to get some Nema 23's in the future. I run mine at 48 volts.

http://www.massmind.org/Techref/io/stepper/THB6064/index.htm

I love mine. I setup my system so I can swap back and forth between printer and cnc. Also remember you can get more torque to the motors with a lower step rate and CNC needs a ton more than printing. So 16 step for CNC and switch to 32 step for printing. The THB6064 can do 64 stepping too if you want to go that far.

Edited 1 time(s). Last edit at 03/27/2017 04:34PM by AquaticsLive.