what can i do now Ramps/Arduino quuesion?

Hi i have not built my printer yet my motors have not arrived but i have my arduino and my ramps what can i start uploading firmware are wait until my printers built just want to power the thing up see it works using the usb as i wont be connecting cheers and is there a wiki on setting up your arduino cheers

ok no problem i got the led to blink thats a start lol

is there a way i can check that my ramps have some sort of power just through usb and that the firmware is communicating with each other without motors cheers

If its blinking, it has 5V power. Install a firmware and you'll be able to communicate with it. Meter the outputs and you can see if its doing things, but its difficult to testit effectively without a machine to wire it to.

yes I tested the light with a simple blink code on the arduino the problem I found is its a fundunio mega 2560 uncertain it will be compatible with the ramps, so i just wondered if the was a test script i could make something flash on the ramps via the board just to check the ramps too

im only plugging my arduino in the usb if I add on my ramps board will I damage the ramps board obviously id unplug the arduino first

ok i went for the kill no smoke and the blue led blinks with the arduino so that 1st plus no fire that's 2nd plus

it would be more fun to check if you can hook the motors

well i need long wires they on dispatch lol

another querie my ramps has 5 stepper drivers i understand to my knowledge you only need 4 1 for for both z one for x one y one for extruder i see that on board it has E0/E1 i gather extruder 1 and 2 so can i remove the spare from the board and keep it safe for spares

no you cant :p

why not if isnt being used whats the point of it being there

Removing it will mess with the space-time continuum

---

Andromedabots -> EU reprap printed parts and electronics supplier

you can use the 5th for a z axis stepper, so that each motor has its own driver. in marlin at least its a simple setting in the config to enable the feature.

andromedabots Wrote:
-------------------------------------------------------
> Removing it will mess with the space-time
> continuum

pmsl, love it another question why do i have two trimpots on the drivers and which is the one i adjust, and best method on first start up when motors get attached

srry i found the wiki about the g3d driver

VREF Calculation Formula

REF = I_TripMax * 8 * 0.1 I_TripMax - Trip current of your motor (A)
Example: 0.4A * 8 * 0.1 = 0.32V


understanding that my motors are 2.5a
so 2.5a * 8 * 0.1 =2v

oops think ive made my 1st mistake and got too powerful stepper motors for my buildmy stepper motors

definitely confused.dot.com, i back tracked myself and went to the stepper motor wiki and found that my motors have been used on other machines, so its back too understanding voltages and stuff to make them run correctly (good job they ain't arrived yet so i can do a lot of reading and posting questions). The learning curve has now hit the steep vertical which i knew i'd approach soon or later lol.

The motors rated power is a maximum, you don't need that much power to make them work and driving them at full power may damage the motor brackets, plastic isn't the ideal material to hold on to a hot motor. Your drivers will provide enough current for the motors to do the job. And don't worry about the rated voltage either, we use chopper drivers that keep the current at the set level so we can safely run them many times over their rated voltage.

so where do i start can i check my output voltages and amperage, can i just have it plugged in too the usb or will i need to plug it into the psu to check the voltages and amp out the the drivers, and a good start would it be making sure that my drivers have the output to 1a as i know they rated to 2a output but start low and increase if needs be. s there and youtube tutorials i can watch or written anywhere, basically i want to test my motors when they arrive i don't want to plug anything in especially once i've attached the psu don't want nothing to fry.

Hi chris

That trimpot is there to adjust the motor current.
When adjusting measure current going through one of the coils of your stepper motor. Current measurements between power supply
of Pololu driver will not be precise. When you measure current put motor in the stall position but don't power them off. Total motor current is calculated
by the following formula;

Im = Ic / 0.7

where Im = motor current and Ic = coil current.

You can also do it only with observation but it may not be as precise, when doing that you have to be careful not to burn out Pololu or motors.

---

Andromedabots -> EU reprap printed parts and electronics supplier

yes i do understand but i want to know what to check before i start plugging things in i don't want to plug my psu to my ramps and blow something and i don't want to plug my motors in and put strain under having the wrong amperage at the start

Well you'll have to check the polarity of PSU and it might be a good idea not to have any Pololus on
when you first power it. When you see that it didn't burn put one in and try spinning a motor.

You have to connect it sooner or later

---

Andromedabots -> EU reprap printed parts and electronics supplier

chris33 Wrote:
-------------------------------------------------------
> yes i do understand but i want to know what to
> check before i start plugging things in i don't
> want to plug my psu to my ramps and blow something
> and i don't want to plug my motors in and put
> strain under having the wrong amperage at the
> start

If your motors are rated for very small amperage then it can be issue but in your case with such of (2.5A!!!) stepper motors you don't have to worry about over amperage.

Your only issue is how to cooling a drivers to let them pump around 1.5-2A, without additional cooling you can go up to 0.8-1.1A without any issues but if you are going 1.1A+ then thermal shutdown to protect driver from overheating just create a mess during printing by shuting down a driver for miliseconds for cooling it down. Fan cooler pointed on the drivers is a must.

You have to know that A4988 is rated for maximum 2A setting anything over it = overcurrent protection will turn off driver for protect it.

As you have G3D A4988 drivers then:
2A * 8 * 0.1 = 1.6V at REF is a maximum going over it = overcurrent protection that shutting down the driver.

And honestly just connect and play with your G3D A4988 drivers and RAMPS board I have done so weird things with drivers and motors I can say that only inserting driver in wrong direction can damage it and over current of motors just killing slowly they life time (which is not a case here due of A4988 is not able to deliver current over your motors specification).

Best Regards,
Martin

www.gadgets3d.com - parts for your 3D printer

Edited 1 time(s). Last edit at 05/08/2013 09:16AM by Martin_G3D.

i know this sounds stupid 2A * 8 * 0.1 = 1.6V at REF and for me to understand that acquisition does than mean because my steppers have the voltage rating of 3.1v I would basically under running them and if i wanted to go on say a mediocre setting run them on 1A i will even more underrun them by only giving them 0.8V

and allow you any laugh out louds and ha has as you like i need a sit down brain hurts lol

Vref is a control signal to the driver chip that tells it how much current to supply to the motors. It has no relationship with the supply voltage, which is simply the voltage you supply to the board, normally 12V.

The rating of a stepper motor is usually the current which raises the temperature by 80C with two coils on, so if you don't want to have your motors running at 100C you need to derate them (or add heat sinking).

The current calculated with VREF in this way is the peak current into one coil, so that already is only half power but still would give a 40C rise. We normally run at about 1A into a 1.7A motor, so that halves the power again giving 20C rise, which is comfortable to touch. The torque is then about half the data sheet value.

---

[www.hydraraptor.blogspot.com]

definitely learning curve this is the data for my motors
Part No.: 42BYGHW811
Frame Size: NEMA17
Step Angle: 1.8 degree
Voltage: 3.1V
Current: 2.5 A/phase
Resistance: 1.25Ohm/phase
Inductance: 1.8mH/phase
Holding torque: 70oz-in
Rotor inertia: 68g-cm2
Detent torque: 280g-cm
Number of wire leads: 4
Weight: 0.34 kg
Length: 48mm


im confused please help i just need a start point

chris33 Wrote:
-------------------------------------------------------
> definitely learning curve this is the data for my
> motors
> Part No.: 42BYGHW811
> Frame Size: NEMA17
> Step Angle: 1.8 degree
> Voltage: 3.1V
> Current: 2.5 A/phase
> Resistance: 1.25Ohm/phase
> Inductance: 1.8mH/phase
> Holding torque: 70oz-in
> Rotor inertia: 68g-cm2
> Detent torque: 280g-cm
> Number of wire leads: 4
> Weight: 0.34 kg
> Length: 48mm
>
>
> im confused please help i just need a start point



Im going this about this the wrong way what im needing to know, whats the ideal minimum torque i need for the x,y,z, motors im using a different geared motor for the extruder, as i see that on the wiki the x,y,z 13.7 N-cm the ones i have purchased are 49.4 N-cm  so 13.7 is 27.73% 49.4 and my motors 100% so ii would have to run the motor 27.73%?