[technovative]

I am working on a 3 axis build using vexta pk266-02b unipolar stepper motors rated @ 3.6v. I noticed in the manufacturers specs that they used 24v for testing? Why would a motor rated @ 3.6v need to be supplied 24v to reach its optimum potential?

During driver testing I have been using a 12v supply regulated down to around 6v which gives me about 4v @ the motor coils after the voltage drop when energized. The motor draws the spec 2 amps @ this voltage. The motor functions ok until I put some drag on the shaft then it bogs down fairly easily (kcam set @ 3200 steps/inch), however the voltage does not drop significantly under this load. Suggestions will be appreciated.

[LeeWay]

Just generally, you can apply 20 times the rated voltage and get closer to the real max rating. Not sure why, but works. Check out some of the Gecko threads stepper motor basics. It explains all this. Welcome aboard. The search feature is your buddy.

[technovative]

I assume that what I will refer to as motor overclocking is only applicable to chopper/pwm based driver configurations?

[ger21]

I assume that what I will refer to as motor overclocking is only applicable to chopper/pwm based driver configurations?

No, but you may need to add current limiting resistors if you increase voltage. They can get very hot and waste a lot of power, but you will get more speed.

[Al_The_Man]

Simply put, General characteristics of a stepper motor.
The largest torque on the motor shaft exist when the motor has a constant motor rated DC voltage applied, at this point the rated current will flow.
When stepping pulses are applied, the current (torque) through the motor will decrease as stepping speed increases.
If you were to increase the pulse frequency, you would reach a point where torque would be so low, synchronism would cease and the motor would stop.
The above assumes you would not increase the voltage to compensate for a decrease in current.
Simple drives will use a series resistor to overcome this and sophisticated drives use PWM etc to ensure a constant rated current through the motor at higher speeds.
Al.

[technovative]

Just generally, you can apply 20 times the rated voltage and get closer to the real max rating. Not sure why, but works. Check out some of the Gecko threads stepper motor basics. It explains all this. Welcome aboard. The search feature is your buddy.

Thanks for the quick response, the suggestions, and welcoming me.

No, but you may need to add current limiting resistors if you increase voltage. They can get very hot and waste a lot of power, but you will get more speed.

Simply put, General characteristics of a stepper motor.
The largest torque on the motor shaft exist when the motor has a constant motor rated DC voltage applied, at this point the rated current will flow.
When stepping pulses are applied, the current (torque) through the motor will decrease as stepping speed increases.
If you were to increase the pulse frequency, you would reach a point where torque would be so low, synchronism would cease and the motor would stop.
The above assumes you would not increase the voltage to compensate for a decrease in current.
Simple drives will use a series resistor to overcome this and sophisticated drives use PWM etc to ensure a constant rated current through the motor at higher speeds.
Al.

I have experimented with 24v supply power and a 2ohm 5w series power resistor and the motor just shuddered and wouldn't run. However as I am still early in the process of putting the electronics together there are most likely other factors involved. Thank you all for your input it has been helpful.