5v stepper motors and ramps 1.4

Hi guys, i'm starting to build my own 3d printer but seems that i made some bad boughts... Here is what i bought

Stepper Motor DC 5V 2-phase 4-wire 1.8 Degree 42mm stepping 3d printer ---> [www.ebay.com]

3D Printer Kit RAMPS 1.4 Mega 2560 R3 12864 LCD Controller 5x DRV8825 Driver --> [www.ebay.com]

When i conect my 5v steppers to ramps they overheat and dont move at all, i'm not sure but i think thats because im supplying them with 12v instead of 5v my question is, there is anyway i can supply then 5v with ramps board? maybe if i lower to 5v the input on ramps itself?

The lcd, hotend and firmware are working just fine.

I would check the coil wiring pairs as per the wiki:
[reprap.org]

The coil pairs should be next to each other on the plug. The wiring diagram on eBay suggest they aren't.
You may need to swap the 2 center wires on the plug that goes to the RAMPS

Steve

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My updated Instructable on our Prusa i3 Build
[www.instructables.com]

Voltage doesn't matter as much as power. If you set the stepper driver bias voltage lower, you may find that the motors become useable, or you may find that they're too weak for the task, and you need stronger ones.

Lowering the stepper driver bias will limit current to the stepper coils which will reduce the produced heat, and may have your motors useable.

how do i lower driver bias? is on the drv8825 potentiometer?

i messed up with the potentiometer and it only got hotter xd
It makes some noises and moves a litle, i think i have to buy other shield isntead of ramps a ULN2003 to drive this 5v motors.

Those are pretty small motors- they only require 0.7A, so the little drivers that plug into the RAMPS board will drive them just fine.

What isn't so fine is the fact that they are small and low current- they will provide little torque. They are quite a bit smaller than most of the motors used for 3D printers.

With steppers, it is not at all unusual to operate them at 10X their rated voltage, so the 12V supply is actually a little low to run 5V motors. They'll turn, but they won't accelerate and decelerate (start and stop) very quickly.

If the motors aren't turning you probably have them wired incorrectly.

I suggest you do a little reading here: [www.orientalmotor.com]

I think i have the wiring figured out cuz it moves but it doesnt move like is supose to, i made a litle video showing what is going on.
When i start messing with the motor turn the volume up to hear the strange noise he does before moving.
stepper motor

In the video i was messing in the 10mm option, the smaller it gets the easier is to control the motor and the hotter it gets also.
Example in the 0.1 mm it moves smooth and has no torque at all like u said.

The noise is typical.

Check your speed and acceleration settings in the firmware of the controller. Reduce both until you get the motors to turn reliably, then start turning them back up a little at a time to find where they work best. Likewise the current setting(s) on the driver board(s).

If the motor driver and/or the motor is getting hot you've got the current set much too high. At only 0.7A the driver and/or the motor should only get a little bit warm, and only after operating for a while.

I don't think those motors will provide sufficient torque to drive the axes in a 3D printer unless it is very small.

Thanks i will mess with those settings.

U were right i had to lower those settings quite allot, now im having problems finding the Vref Pin on my DRV8825 to lower the current. Here [www.pololu.com] says "The ref pin voltage is accessible on a via that is circled on the bottom silkscreen of the circuit board." i dont undestand what they mean in that sentece...
I tried to measure in the fallowing point, but there is no voltage drop.

i think i found my answer "v-ref checking, + probe on the turnpot and - on a ground pin"

Game over ! Fried Arduino , Fck this sht

Thanks for all the help

ok maybe u guys can help me, seems that the arduino works with the usb power, but doest work if the only power source comes from the ramps 1.4. Any ideia where is fried?

nvm is really death.... 1 month waiting this thing to arrive, 1 day its death... amazing

Two of the great benefits of those stepper driver modules is that they are cheap and easily replaced. The only reason these are benefits is because they fail frequently. One common failure mode is breaking the tiny, fragile pot used to adjust the motor current. You've also discovered one of the other problems- measuring the motor current (by measuring the reference voltage) is tricky. Where do you measure it? What happens if the voltmeter probe slips and shorts a couple pins on the IC? Buy a few spares and keep them handy.

For your tests, try setting the pots at about mid rotation then mess with the firmware speed and acceleration settings.

If the Arduino board works when powered by USB but not by the 12V supply, you've probably killed the 5V regulator chip that drops the 12V down to 5V. Either that or you've killed the 12V power supply. If it's the regulator chip, you can easily replace it with an LM7805 or other cheap three terminal regulator, even if it isn't surface mount. Be sure you check that the pin out matches the circuit board before you solder it down.

yup i fried that voltage regulator that one i'm sure, but before that i was trying to measure the Vref across the potentiometer and gnd of the driver and instead of using dc voltage it was in ac voltage, and somehow something broke, im not sure if that's what fried the voltage regulator because after that i messed with another power supply and that really broke the voltage regulator.

U are saying i can replace it with a lm7805? but the one in the board has 4 legs, i will be checking this option cuz i got one lm7805.

I tried to replace the voltage regulator fallowing [www.instructables.com] and somehow i managed to damage the board