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Member #182165

Member Since: December 22, 2010

Country: United States

  • Ok, so you need to read the specfications. NO your easy driver cannot correctly provide enough current for this motor. (Just because it says 2Amps for the new version, that assumes proper thermal managment, AKA cooling). The reason it seems to turn on and off is you are overheating the easy driver. This motor must be limited to 1.7 Amps from your voltage source by the stepper driver. If you start out with 12 volts or higher, the 1.8 Ohms of the motor coil is going to result in more than 1.7 Amps. But that’s why we use switching stepper driver that PWMs the output of the H-bridge and limits the current. The thing to keep in mind too is that it’s an inductor and thus that 1.8 Ohms is not the complete picture. When the motor moves, we turn off and on the coils and that frequency too affects the complex impedance of the coil. Thus the the apparent voltage across the coil changes to result in the same current as the motor speeds up or down. This is why we want the higher source voltage, to ensure we have enough headroom to attempt to keep the same current (and thus magnetic strength which creates the torque). Again, the key here is that the stepper drive actively limits the current via PWM to the motor coil. That means the driver will kick off a fair amount of heat as the energy must go somewhere and the 1.8 Ohms of the motor isn’t going to disipate much. When you turn down the current potentiometer of the stepper driver to a level where it can survive (most say about 1 Amp or less on an easydriver) then you will get about half the rated torque at best. You really need an industrial rated driver (2 Amps or more and heatsinked) to properly run these motors at spec. Again, to be clear, while you might slap a heasink onto the easy driver and add a fan, it may not be enough to properly run this motor at 1.7 Amps in all conditions. You can turn the current down, but then you do not get the rated torque.

  • No, it’s not the amps, it’s the inductance that is killing the speed. The larger nema 17 is a low inductance motor and thus looses torque at speed at a much lower rate. You cannot beat physics, an inductor takes time to reach current, the larger the inductor, the longer the time. So if you cannot change current in the poles fast, obviously you cannot make a rotor spin fast with much torque. These motors were wound for 12 volts such that a simple H-bridge could drive them with no current limiting as the motors are “self” limiting by design. Modern drivers current limit the coil and thus you use a higher voltage, but this is really only effective on low inductance coils, otherwise it just ends up as waste heat (the high resistance factor comes into play).

  • All Nema 17 motors are going to use M3-.50 metric screws since it’s a metric size motor with a 5mm shaft. Basically when they said 4 they meant 4 each, M3 metric screws and the only popular thread in M3 is 0.50. Valid question.

  • Carbon offsets should be criminal. Really, do some homework and see how little carbon offsets help the environment. They take the money and run. http://www.washingtontimes.com/news/2009/mar/08/carbon-offsets-scam/ http://thebreakthrough.org/blog/2010/06/more_fraud_in_carbon_offsets.shtml

    Sparkfun is a smart company that does it’s best to prevent waste (love their shipping boxes), and follow green point of manufacture processes. While you brought up some other good points, please see for yourself how many scams are embedded in the green movement. It’s not that I don’t support green ideas but please tell me you are smarter than giving someone money to offset carbon. The concept is just stupid. Please donate your money to a worthy cause and not some organization that its whole point of existance is to rip you off, so they can drive the big SUV and have 7 homes, a private jet, and destroy the enviroment. Again, if you feel dirty and need to donate-plant a tree in your neighborhood and watch it grow. In fact, setting the money on fire so you don’t spend it (on stuff that is the problem) is actually more effective use than sending it to carbon offsets.

  • PLA Poly(lactic acid) is old news-every Reprap user has some lying around. It’s not some miracle plastic and further, lets not get into name branding. Ingeo is a brand name of PLA just like Teflon is a brand name of PTFE. You cannot go around calling everything Teflon, nor is it all Ingeo. Also, it still takes energy to make PLA so despite it’s “green” cough cough source, it’s energy (AKA OIL) consumption to make it is just as bad as ABS. It’s also fighting ethanol and food uses of corn. http://environment.about.com/od/greenlivingdesign/a/pla.htm

  • I got this to work great right away. I am using putty on Windows 7 since there is no more hyperterminal. Just opened up the com port at 9600 and it worked. It says “ready” when you press the reset button anytime the Arduino is powered on. It did skip a couple of times, like stuck on repeat but that could have been stray capacitance since I was holding the Arduino. Creative spelling will get the sounds your looking for (example is u is often better replaced by o in most words. YMMV.
    Yes the new board is SMT, but the pinouts are identical, just be extra careful when soldering, clean your tip before every tiny joint.

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