power supply test

[dlenox]

Am awaiting a 24v 6.5amp power supply so I decided to do a test.

I have some 116oz bipolar stepper motors and using Xylotex control board. While waiting for some parts to complete my cnc router I decided to perform a drive test.

Using a 12v, 7amp switching power supply from a computer (instead of 24v) I connected controller and motors, and as instructions said I set the VRef to about 3.6volts.

I was dissapointed to see that the stepper motors lost quite a bit of steps. In my test setup the motors were connected to the screws but not to anything else.

I always believed that it was amperage and not voltage that provided the torque, but was easily able to get them to loose steps with just a little bit of drag by pinching the screw with my finger tips.

Was this a valid test? and will the 24v power supply really make the difference?

[ger21]

Can you turn the screws with your hand when they are not spinning? With the lower voltage, you'll have full torque when the motor is NOT spinning, but torque will fall off very rapidly as rpm's increase. 24V will keep the torque up at higher speeds. 24V should double the speed your getting with 12V. Did you wire the motors parallel or series?

[dlenox]

Yes the screws turn very easily by hand as they are supported by bearings on either end.
The motors tested were one on X axis and one on Y axis.

[ger21]

I meant with the 12V turned on. They should be holding strong enough to keep you from turning them.

[dlenox]

Gerry,

with the 12v on I can not turn screws by hand.

[balsaman]

You will get more torque at speed with higher voltage. Don't worry about it. How fast did you have them spinning?

Eric