Help motor voltage ???????

[level head]

help please, i am getting every thing for my cnc mill (electronic area of it ).And i understand everything except the part of what power supply to use .

i went to cnc- zone and found somethings out like this wiring diagram
http://www.cnczone.com/forums/attachment.php?attachmentid=19401

but in order to get the right power supply i need to know the right voltage of the motors i am using .
motor specs of of ebay

Holding Torque (2 phases on)......8.7 (1208) Nm (oz/in) +/- 10%
Rated Current per Phase.......................................6.0 (Amps DC)
Phase Resistance...................................... 0.45 (Ohms +/- 10%)
Induction (mH) +/- 20% typical........................................... .....5.1
Motor Length (mm).............................................. ....................118
Rotor Inertia (g-cm^2)............................................. ..............2700
Weight (kg).............................................. .................................



it doesnt tell me the voltage of the motor

so can anyone tell me what is the right power supply ,and what is the voltage of the stepper motor i would need to use on
this setup with my gecko drives and my motor setup

http://www.geckodrive.com/product.cfm?pid=10

thank you very much for any input ..

[MTNGUN]

Gecko publishes some good info on stepper motors. The bottom line is, the voltage needs to be compatible with your driver, so look at your driver's voltage specs.

I'm running about 36V on my Geckos. If I remember correctly, more voltage increases torque slightly, but also increases heat. I think 24V - 80V is the common range for steppers.

[Todd Tolhurst]

Typically, you'll use a supply voltage several times the motor's rated voltage. With Gecko's, you'll run between 24 and 80 volts. Gecko has a very good introduction to steppers at http://geckodrive.com/photos/Step_motor_basics.pdf .

[John Stevenson]

From these specs it sounds like a 42 series motor, is it 4.2" across the flange at the front?

If so only the Gecko can drive these OK but the the amount of detent torque they have to overcome.

The Gecko's have a jumper inside to select 42 frame motors.
You really need as much voltage as possible to get these moving.

Start off with a 48 to 50 volt transformer AC, by the time it's been rectified and smoothed it will be at around 70 volts giving you 10 volts safety.

Even if this is a 34 frame motor [ 3.4" across the flange ] the same applies except you won't need the jumper setting inside the Gecko.

.

[Evan]

The guys aren't doing a very good job of explaining this. Stepper motors have a maximum rated dissipation in watts they can handle. The nominal motor voltage is determined by the phase resistance and the rated current. It will sometimes be listed but not always. Those motors are rated at 6 amps continuous current and have a phase resistance of 0.45 ohms so the voltage rating is about 13.3 volts.

The reason it isn't listed is because the voltage isn't the limiting factor, the power dissipated in the coils is. Steppers are not driven by a continuous DC voltage. Not only does the voltage switch constantly from one phase to another but the driver circuitry provides a high frequency "chopped" signal that pulses on and off many times per second when a phase coil is energized.

This allows the use of much higher voltages to drive the motor and makes the motor much more responsive and efficient. It provides much greater starting torque and acceleration than a continuous DC voltage would and reduces losses in the motor. The chopper circuit is adjusted so that the average current does not exceed the motor rating so the motor doesn't burn up. The drive will have an adjustment that controls the motor current. This needs to be set for each type of motor powered by the driver.

[John Stevenson]

The guys aren't doing a very good job of explaining this.

Sorry.

Mind you Tods link to the horse's mouth was dead on.

http://geckodrive.com/photos/Step_motor_basics.pdf

.

[Timleech]

Not wishing to hijack the thread, but I have a slightly different voltage question.
I've been looking for a while for a suitable DC servomotor to go with a Haas indexing controller. Haas aren't very forthcoming, but they did give me a motor type number which is one of three they used with this controller. That particular motor comes with several different winding options & they didn't specify which one.
I've found a motor which is a close match in terms of torques etc., but the rated voltage is 96V. The motor supply TO the board is labelled 150V DC.
Is this likely to turn board or motor into a smoke generator?
Alternatively, if I use a slightly bigger motor but rated at 150V, is the board likely to have current limiting circuitry to protect itself from overloading, or will that be another recipe for smoke?

Thanks
Tim

[John Stevenson]

Tim,
I'll swop you a 150v motor for the 96v motor. ?

.

[Timleech]

Tim,
I'll swop you a 150v motor for the 96v motor. ?

.

I could be tempted ;)

The motor Haas specified was the EG & G 3509.
I've been told that's the same as the CMC 3509, which can be found here:

http://www.cmccontrols.com/brush_servo_motor_platform3500.asp

If yours is somewhere near that spec, I'll be seriously tempted :)

Tim