Geared stepper motors and drivers

Other Hardware Motors, Mechanics, Power and CNC
1

I am looking for fairly high torque stepper motors of maybe 1200 oz-in holding torque and I see it's fairly expensive when you have to buy the drivers, controller and power supply, then I came across a geared stepper motor. I am unsure of what the difference is between a stepper motor and geared stepper motor. Does a geared stepper motor have more torque, decrease the speed etc...?
I was looking at this one: http://www.ebay.com/itm/Nema23-stepper-motor-Gear-motor-15-1-Ratio-3000oz-in-3-0A-CNC-Engraving-/271275366891?pt=LH_DefaultDomain_0&hash=item3f294599eb
NOTE: In the link above it says 3000 oz-in and at the bottom of the page at the specs it says 140 n.cm? I believe there's a big difference!

Also I was looking at stepper motor drivers, could anyone tell me whether I can move a stepper motor by just 1 step at a time or an increment that small.
I was looking at these:
http://www.ebay.com/itm/130839628814

http://www.ebay.com/itm/HOT-SALES-4Axis-Stepper-motor-driver-DM860A-PEAK-4-2A-18-50VDC-CNC-New-/190698084078?pt=LH_DefaultDomain_0&hash=item2c667dd6ee

Also how many steps are in 1 stepper motor rotation
and last of all, could a 428 oz-in or 1020 oz-in holding torque stepper motor lift a 4kg weight connected to the motor spindle 0.7m away from a vertical 115 degrees into the air.

Any help on any of these questions would be appreciated! :slight_smile: :slight_smile:

2

The 140 N-cm figure is for the motor, 3000 oz-in is for the output spindle. 1.4 N-m and 21 N-m in SI units.

Yes gears exchange torque for angular velocity whatever kind of motor you put them on!

Also how many steps are in 1 stepper motor rotation

Commonly 200, but you always read the datasheet.

and last of all, could a 428 oz-in or 1020 oz-in holding torque stepper motor lift a 4kg weight connected to the motor spindle 0.7m away from a vertical 115 degrees into the air.

Cannot understand that description. Perhaps a diagram?

3

4 kg at 0.7 m = 3880 oz in
So no

Be aware of backlash issues with gearboxes though, low backlash gearboxes are needed for bidirectional use normally to maintain positional accuracy, they can be hideously expensive.