Hello,
I'm French and I have a small problem. I want controller manually two step-by-step motors (NEMA 17 I think), and I have only one Arduino Mega card and one RAMPS 1.4 shield (with four step-by-step motor controler).
I haven't temperature sensor or endstop.
I only want manually control my step-by-step motors for try my home-made structure, I don't want print any part.
Can you help me, it's very important.
Thanks guys.
Hello mathieu,
You need to start by understanding more about stepper motors. See THIS:
And the 3D printer guys have an excellent page HERE:
Désolé, en anglais .. 
Do you have anything loaded into the Mega already? Since the RAMPS board is intended to be used with a reprap, I'd be inclined to load some of the existing firmware and either hack it or provide it some custom Gcode that moves your motors.
For purposes of testing my reprap, I've used the (now obsolete) Tonokip firmware and just replaced it's loop function with one that calls the step functions directly. You'll just need to ensure that the wiring is set up as the firmware expects, or adjust the pin config until it does .
Thank you for your answers.
I've tried to change firmware Marlin, but I can not turn off the temperature sensors. In addition, I think the fact that I no endstops block engines.
Tomorrow I'll try to find résistances and endstop to test with a complete assembly.
If somebody is able to offer me a firmware for the Arduino Mega, I would be very happy.
Thank you very much.
hey!
maybe too late, but here go:
I know this is an old post. There are readily usable unit for manual control of steppers shown below.
http://lechacal.com/wiki/index.php/Stepper_control_v3
http://lechacal.com/wiki/index.php/Stepper_UNO_v1.0
Marlin firmware will stop and complain about missing endstops and thermistor, correct.
Instead of hacking Marlin to work as a non 3D-printer, look at this instead:
GRBL is the way to go for your project.
// Per.