Power supply and Nema 17

[woodturn]

So I'm thinking about buying these Nema 17 steppers for a little bechtop VMC, but I only have a 24V power supply. I think the manufacturer recommends a 34V power supply. I plan to drive it with the xyoltex driver which will only handle 30V. Will it work? I think so do you?

http://web3.automationdirect.com/adc.../STP-MTR-17048

http://web3.automationdirect.com/sta...stepmotors.pdf

Thanks y'all

[jeffs555]

The voltage rating on those motors would be 2.8 volts(2 amps x 1.4 ohms), and for best speed, you generally want a supply 10 to 20 times the voltage rating. A 24 volt supply would be slightly less than this, but should work OK. The maximum speed you can run a stepper is directly proportional to the supply voltage.

[woodturn]

will it affect the torque?

[jeffs555]

The supply voltage will not affect the holding(ie static) torque. However, the torque of any stepper motor drops as the speed(ie step rate) is increased. At some speed, there will not be enough torque to overcome the friction and cutting forces in your system, then the motor will lose steps. This speed depends on your machine and what you are cutting, but for a given machine, doubling the voltage will approximately double the maximum speed.

Most motor manufacturers show torque curves for their motors to show how torque drops with speed, and these curves are usually for a single fairly high supply voltage. You can't precisely interpolate for lower supply voltages, but you can get some idea by dividing your supply voltage by the voltage used for the curves, and then multiplying all the rpm or pulse per second numbers by this.

In your case, using a 24 volt supply will result in about 70% of the speed of the 34 volts used in their torque curves, and 80% of the speed of the 30volt max supply for the Xylotex, so you would not lose much by using a 24 volt supply.

[woodturn]

Thanks, I ordered the steppers today. I'll let you know how they work.