Got the Moon's stepper datasheet

[Ryan Carlyle]

The Moons' 17HD-4063-xxN short-stack NEMA 17 is probably the 1st or 2nd most common stepper used in 3d printers worldwide. All the Makerbot Replicator 1/2/2x and clones use them. They're a great size for direct-drive extruders and other moving motors. It's been bugging me that I could never find a datasheet, so I shot Moons' an email and they helpfully provided one. They also asked a bunch of questions, like, "how did you find out about it" and "what is your application" so I suspect they may not know that there are perhaps a half million of these things in 3d printers around the world...

Note the 0.3 Nm torque rating says "Two phases on/rated current" which I think means they are over-driving the motor to get that much torque. With microstepping drivers you only do two phases on at 70.7% of rated current or one phase on at 100% of rated current. If you back out that best-case "will overheat soon" rating to the normal way the motor is actually used, it would be 0.21 Nm holding torque. That matches extremely well with the value predicted by my back-emf measurements and calculations. 

[JF Kansas]

Nice, you probably knew more about it than the Rep you were talking to. 

[Dan Newman]

And for amusement, here's the old stepper motor MBI used on the Cupcakes and then the
early Thing-o-Matics. Ed Nisley got on MBI's case about how lousy they were and
why and, I suspect, helped them in choosing that Moon's stepper you posted the
specs for. (It was likely some combination of Ed and Zach "Hoeken" Smith who
picked that Moons.)

Dan

P.S. Note the 35 Ohm resistance per phase.

[Ryan Carlyle]

"Rated voltage 14v" lol, nope, that's not gonna work real well for this application.

[Ryan Carlyle]

Got the 24v torque/RPM curve too. See below and attached. 

Looks like their test jig had some bad resonance issues when half-stepping at low RPM. Should be a pretty flat plateau on the left for our microstepping systems.