[bonmotwang]

Just reading the spec from KeLing's new website. I am looking for a NEMA23 570oz.in step motor for CNC BF20L.
But I found a torque curve chart, the max torque is about 3N.m, 423oz.in.
A little confused here.
I attached the chart here.
Any body can explain what does the 570oz.in in the spec really mean?

Thanks

[doorknob]

The 570 oz-in rating would be a "holding torque", that is, the rotor should not rotate if a torque of 570 oz-in is applied. The holding torque is generally greater than the available torque when the motor is turning. The torque curve that you included in your post starts at 100 rpm, so the 0 rpm holding torque is not plotted.

If I did the conversion correctly, 570 oz-in is about 4.0 newton-meters. So it is not out of the question that that would be the holding torque of the motor for which the torque curve was given.

[James Newton]

What doorknob said. If you are trying to figure out what size stepper you need for a given load, this web page may help: techref.massmind.org/techref/io/steppers.htm#Estimating