The motor is running but it is slow and does not have much torque. Are these the wrong drivers? Is there anyway to make this work. I am short on time and have a limited budget.
Thank you in advance for any help you can give me.
The EasyDriver is for hobby motors, and is only rated up to 750mA per phase. Your "big steppers" can produce big torque but only at big currents: the datasheet suggests up to 7A per phase in the parallel connection (highest torque).
I would suggest a more powerful stepper driver (our own Rugged Motor Driver is definitely a step up in the power category, but still doesn't reach 7A).
Perhaps look around robotics sites (Pololu, Robot Shop, Acromame, etc.) They're usually a good source for motor control/drivers.
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The MegaRAM shield: add 128 kilobytes of external RAM to your Arduino Mega/Mega2560
Yes you are using way too little current. Those motors can take 7A but your motor drive can only deliver one tenth of that. Also can your power supply give you so much especially for four motors?
You need a much more capable regulating driver, that is one where you can set the current.
These people have some high powered stepping drivers:-
But you haven't filled in your location in your registration form so there is no way of knowing where about in the world you are.
If you have 4 motors at 7A per winding you are looking at a power supply with the capability of 470 Watts, that is very big and if you don't have one very expensive. Yo might not want to run the motors at the full 7A per winding. However as there are few deletes you are sharing it is hard to say.
If I am using something like you have suggested where can I get information about coding for the arduino. I am sorry but I am kind of new to all this stuff. I chose the easy driver mostly because it had a tutorial and I could learn how to write the code. Can I use the same code/
Again I can't thank everyone enough for all the help.
Programming is easy, with this sort of driver you just have two inputs STEO and DIRECTION. You set the direction high or low depending if you want clockwise or anticlockwise, and then you just pulse the step line, that is set it high and then immediately set it low again. The delay between the pulses gives the speed. So a simple for loop will move it as many steps as you want. As your motor has 200 steps per rotation you can work out how far you want it to turn.
I am located in NYC.
OK fill it in in your profile page then it gets posted with every post.
By the way I am coming to New York in a few weeks for the Maker Faire, I will be showing some of my stuff there.
Sorry no, that is not a stepping motor control board it is a spindle controller. A spindle is the thing that rotates the cutting blade on a CNC like a drill.
The website says:-
Note: This product is used in conjunction with an electronic motor speed control board.
Some speed boards do not have a reverse feature. An independent 12 V supply must be used with this board unless the optional DC/DC convertor is fitted.
Can someone explain to me how the driver is regulating the current? I was under the impression that the circuit would draw as much or as little current as was needed. Can someone explain to me how this is working? Thank you very much for your time. I apologize for all these newb questions.
The driver has a current sensing resistor in series with the coil. The power is turned on and the current starts to rise in the inductor. When the current reaches the required level the power is then turned off. This cycle is repeated rapidly. This is known as a switching regulator or chopping circuit and is widely used with stepping motors.
I was under the impression that the circuit would draw as much or as little current as was needed.
This only applies to some components like ICs. If you look at the data sheet for your motor this will be true at about 3V. However, you want to get current into the motor coils quickly, (in order for it to run fast) to do this you need a high voltage. But a high voltage would make it draw too much current so it needs to be limited like this.
Just because your motor is capable of 7A per winding does not mean you have to run it at this. The switching regulator driver will allow you to set what ever current you want. The more current the more torque. I would have thought that running it at 1 to 2A would give you lots of torque, but I am not sure as you haven't said what your application is.
You can drive your motor with 3V with a non regulating driver like you had but if you try and run it at 12V like you did it will take too much current. I suspect your power supply was incapable of supplying this much current and so the voltage collapsed and you had very little current and so very small torque.
Well that looks like quite a beast of a power supply. You might have to add some large capacitors as well when you attach the chopping driver because this increases the ripple current. I had problems with a 160W PSU oscillating when driving just three motors at 1A per winding. This caused the large surface mount capacitors on one of the driver boards to melt as it was trying to bypass too much current. I fixed this by adding about 500uF in capacitance across the supply. Replacing the capacitor fixed the board.
Dealing with large currents is not straightforward, just in the way home cooking doesn't scale up to factory production so what you can get away with at 1 amp is not the same as what you need when you start switching 20 amps.
Looks like your 8-wire motors can be wired as "bipolar" with a center-tap going to power supply. That means you have 4 circuits to step through the sequence for stepping.
There are good libraries with stepper motor control for Arduino:
The Arduino Library for Stepper motors is : Stepper - Arduino Reference (This comes with the regular Arduino free software: Sketch > Import Library > Stepper. )
An advanced Library with more functions is AccelStepper: AccelStepper library for Arduino. (This Supports acceleration and deceleration, and multiple simultaneous steppers, with independent concurrent stepping on each stepper)
Your motor's windings are 2.2V at 7 amps each. With a 12V supply you can use series power resistors to drop the voltage (12 - 2.2 = 9.8V) so (R=E/I so 9.8/7 = 1.4 ohms. so something like 2 ohms 100 watt power resistor. This also greatly increases the rate at which current rises in the inductive mortor winding, so you can step a lot faster than with voltage applied directly to the motor.
But modern stepper drivers use pwm to control the current and do away with those big resistors. But that''s more complex.
You could drive 4 optically isolated Power FET switches like these: http://arduino-direct.com/sunshop/index.php?l=product_detail&p=60
BUT you need to manage the length of PWM pulses, AND also provide transient reverse-current protection or you'll damage the power FETs.
Unless you are willing to really design a Stepper Driver of this power, you might want to buy a commercial unit.
Welcome to the world of motion control. You've got big steppers, but now what? Why did you need such powerful steppers? You say "I need speed and torque," that's a meaningless statement, every motor delivers "speed" and "torque". How much speed do you need? How much torque? What's your drivetrain? What's your payload? How fast must it move from one location to another? How distant is one location from another and what's your desired positioning resolution? All of these things are as important as the selection of the motor and the driver.
If you chucked down a few dollars, you can get a proper high-performance step/dir driver like those from Gecko: the G210 can do 7A @ 80V. http://www.geckodrive.com/g210-p-35.html